# Effects of EMP on LED Lights?



## donn (Mar 3, 2003)

Sorry if this is a bit of a strange question but I'm curious about something. I was chatting with my dad the other day about general preparedness as hes been getting a few things together for if the lights ever go out. He was looking at my CMG Infinity green and thinking it would be handy to have in a kit. When I told him it used circuitry to regulate the flow of power from the battery (basically what it says on CMGs website) he asked me whether that circuitry would still work after being hit by an electromagnetic pulse. The same thing generated by an nuclear explosion. He read somewhere that an electromagnetic pulse from a blast has a far greater range than the explosive effect of the bomb, so even if your not in range of the blast (say 70 miles away) you'd still get hit by the pulse which would destroy all your electronics.
So it got me wondering, if ever a terrorist detonated a nuclear bomb or an 'E-Bomb' would all the regulated flashlights (A2's and the like) cease working?
Cheers


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## INRETECH (Mar 3, 2003)

*Re: Electromagnetic pulse*

Not only would the flashlights stop working; its a good bet that the LEDs would get damaged also..


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## LEDmodMan (Mar 3, 2003)

*Re: Electromagnetic pulse*

Most damage from EMP occurs when the electronics in question are either turned on or moving during said EMP event. If they're moving, this will induce a current in the electronics as the EMP wave passes by. As long as there is no current going through the circuit, no damage can occur(remember the scene in the movie 'Broken Arrow' with John Travolta where there they are told by his character to turn everything off just before the bomb detonates). This is correct to the limit of my knowledge in this matter, however, if I'm wrong, someone please feel free to correct me.


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## Orion (Mar 3, 2003)

*Re: Electromagnetic pulse*

If they weren't on at the moment, why WOULD they be damaged? /ubbthreads/images/graemlins/confused.gif


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## AlphaTea (Mar 3, 2003)

*Re: Electromagnetic pulse*

LEDMOdMAn:
You are correct,
They most likely * would not * be damaged by the EMP


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## flownosaj (Mar 3, 2003)

*Re: Electromagnetic pulse*

All I know about EMPs are what I learned in the Army. We were told that we could protect our radios by wrapping the cords and such in a layer of....aluminum foil.


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## flownosaj (Mar 3, 2003)

*Re: Electromagnetic pulse*

Pause for laughter.... /ubbthreads/images/graemlins/yellowlaugh.gif


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## flownosaj (Mar 3, 2003)

*Re: Electromagnetic pulse*

If you think about it...military equip is most likley shielded. Wrapping a conductive layer around the radio will act as a shield for those points of entry. 

Best way I can think of it is to seperate the conductive areas with a layer of non-conductive....instant shield.

Wrap the infinity in electrical tape and aluminum foil...if it doesn't work then I was wrong /ubbthreads/images/graemlins/tongue.gif


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## Abe Furburger (Mar 3, 2003)

*Re: Electromagnetic pulse*

Hi,

From my knowledge (35yrs in electronics), even if equipment is turned off, it can still be damaged.

An EMP can induce a voltage in an led or ic that is much more than it can handle.

Similar question - can a lightning strike knock out electronics even if they are switched off - of course, YES.

Gotta go - more later.

Abe.


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## AlphaTea (Mar 3, 2003)

*Re: Electromagnetic pulse*

[ QUOTE ]
*Abe Furburger said:*

Similar question - can a lightning strike knock out electronics even if they are switched off - of course, YES.

Abe. 

[/ QUOTE ]

While this is true, isnt it usually because the high voltage arc's across an open switch? I have never heard of (altho it may be possible) of an UNPLUGGED piece of equipment being damaged by lightning unless directly hit.


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## Abe Furburger (Mar 3, 2003)

*Re: Electromagnetic pulse*

Having worked in an electronics test lab, where I performed lightning tests on the subjects (amongst other tests), I can tell you that nothing to do with high voltage/current is predictable, and that while equipment may be able to be proofed against most near lightning strikes it is no guarantee that it will pass every time.

Now to my knowledge, the new EMP type weapons use a high amplitude pulse of microwave energy, and to shield against this is rather difficult on portable equipment, or equipment meant to use an antenna.

About metal flashlights, - they are generally very well shielded except for the lense end.

Now depending on the orientation of the flashlight to the incoming pulse, it may be able to survive without a problem.


My feeling on microwave pulses is that even such things as bulb filaments in bulbs that are not even in a flashlight could be burnt out. Have you ever put slivers of metal into a microwave oven? - try it - put a dud CD into a microwave oven for 5 seconds and see what happens to it (put it on top of an empty plastic cup so it doesn't discolor the tray). Was the CD turned on? no it wasn't. It even works with 2 halves of a grape put in close proximity (about 1mm).

All the best,

Abe.


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## Nerd (Mar 3, 2003)

*Re: Electromagnetic pulse*

Ah.. thanks for the very informative post Abe. You refer to the metal flashlights as very well shielded. But as for grounding? Will the EMP induce current into the metal flashlight? If so will any circuits inside it be fried?


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## Sigman (Mar 3, 2003)

*Re: Electromagnetic pulse*

In the AF we used to "light up" lights/lamps with radar (and "enough said"...), never saw a bulb/lamp "blow" but "mysterious" things can be made to happen by "Jimmie & Mr. Wizard"!!


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## BF Hammer (Mar 3, 2003)

*Re: Electromagnetic pulse*

[ QUOTE ]
*Abe Furburger said:*


Similar question - can a lightning strike knock out electronics even if they are switched off - of course, YES.

Gotta go - more later.

Abe. 

[/ QUOTE ]

If the energy of the lightning is high enough by the time it gets to the switch, the power can arc across the switch and damage the device. My not all devices are switched on the AC side also. Many of the photocopiers I've repaired following thunderstorms over the years had power supplies that were connected directly (through fuse or breaker) to the power mains - the main switch controlled the DC side of the power supply. I've also seen lightning energy flow into a device through the earth-ground, specifically in a garage-door openner in my parent's home when lightning struck a tree next door. I had every telephone and an answering machine get damaged in my home by a lightning strike that put current in the phone line.

Getting to an EMP pulse, semiconductors and integrated circuits are the weak link in electrical devices in a nuclear attack. The microscopic interconections within the silicon IC can be burned out just from static electricity during handling, and are just as easily damaged by a high-energy pulse of radio-frequency across the electromagnetic spectrum. I'm certain a department of defense engineer might have the details of just how far from ground-zero you can expect an electrical device to be damaged by EMP, if it isn't classified.

/ubbthreads/images/graemlins/twak.gif - no message, I just like this graemlin!


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## tvodrd (Mar 3, 2003)

*Re: Electromagnetic pulse*

My (limited) understanding of nuclear weapon-generated EMP is that it requires the weapon be detonated at extremely high altitudes (ionisphere) where the subatomic particles emitted can react with the earth's magnetic field. I believe the US tested one on a rocket in the pacific in the 50's and knocked out part of the power grid in Hawaii. I don't think that low altitude/surface bursts have significant EMP effects. That's just from reading a few articles over the years.

Larry


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## Abe Furburger (Mar 3, 2003)

*Re: Electromagnetic pulse*

[ QUOTE ]
*Nerd said:*
Ah.. thanks for the very informative post Abe. You refer to the metal flashlights as very well shielded. But as for grounding? Will the EMP induce current into the metal flashlight? If so will any circuits inside it be fried? 

[/ QUOTE ]

Very hard to tell.

My feeling is that you are less likely to have problems if you do not ground the device as the whole device will rise in potential as a single unit.

But if you ground it, especially with a high rise time pulse, then you may have the possibility of a potential being generated across in the device, which may cause functionality problems.

In closing, for storage, my best bet would be to wrap the device entirely in multiple layers of conducting foil, then a few layers of insulating material, then foil, then insulating material on the outside.

A bit like an alfoil/gladwrap sandwich.

Without this protection, I doubt it would survive.

As for the comment about radar operators lighting up light bulbs etc, a microwave pulse from one of the new weapons would be orders of magnitude greater than that of a typical microwave installation.

Regards,

Abe.


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## Wylie (Mar 4, 2003)

*Re: Electromagnetic pulse*

Just my two cents on the military applications of aluminum foil to power cords. A lot of computer cables have a shielding very similar to aluminum foil and for very similar reasons. The computer rooms are very well grounded or should be, but that is getting a little off track too. It is just EMFs and not EMPs. Close by anyways I figure. /ubbthreads/images/graemlins/icon3.gif 

I guess I kind of have four cents on this one. With the atmosphere evaporating at that kind of rate would there be some sort of static charge at least. I mean go figure, bust up all of that H2O in the atmosphere and you bound to get some sort of a static charge, at least some lightening or something at least. And then again me myself and I the armchair chemists could be out to lunch again. /ubbthreads/images/graemlins/icon3.gif


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## Minjin (Mar 4, 2003)

*Re: Electromagnetic pulse*

Oh come on...everyone's dying to ask the one question that is burning on our minds: How do we make an EMP device? /ubbthreads/images/graemlins/wink.gif

After all, isn't this the Electronics and Other Mad Scientist Projects forum? Reminiscent of the scene in Cryptonomicon where they activate an EMP device in the back of a van...

Oh yeah, anyone ever hear the old trick of tying a knot in a power cord to prevent damage if lightning should strike? /ubbthreads/images/graemlins/smile.gif


Mark


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## shankus (Mar 4, 2003)

*Re: Electromagnetic pulse*

From what I understand about this subject, shielding electronic devices would do no good at all if the shield weren't carried to ground. The voltage induced by the pulse needs a path to ground. And the fact that semiconductor devices can't take very high currents just worsens matters. Aircraft with fly-by-wire flight controls are double shielded with a very thick braid specifically for this purpose. Any noise induced into the flight control computers would cause the aircraft to be unresponsive, or make uncommanded maneuvers. Shielded cables which have their shields tied together on both ends create "ground loops" in which noise induces a current that can put more noise on the conductors than if they weren't shielded, in some cases.

EMP damage would be much more widespread if a nuke were detonated at a very high altitude. But there would be EMP in any case. Nukes are always detonated at some altitude, never on the ground, (underwater though). In fact, a first nuke would most likely be detonated at very high altitude, just for the EMP effect. It would damage a lot of electric and electronic devices, making a retaliation less severe. If you were close enough that it damaged a regulated LED light, you're screwed anyway. (Especially if you see the flash, that would eliminate your need for a flashlight altogether.)

I worked with a guy for 4 years at my last job, that was an electronics/avionics flight test tech going way back to the SR-71 days. He worked SRs, F-117s, A-10s. He also did some instrumentation work for some underground nuke tests in Nevada. These underground nukes detonated in Nevada, had measurable EMP in California, where the instrumentation was. In fact, he said the data from the first test were unusable, because the pulse was much higher than anticipated, and the instruments were calibrated for too low a pulse.

I have the DVD "The Atomic Bomb Movie". They covered that test from the '50s, that was mentioned above. If I remember correctly, it said that that test disrupted communications for 8 hours, and damaged circuits from Hawaii to New Zealand. I'll look at that part again, and post the altitude, yield and any other specifics.


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## Sigman (Mar 4, 2003)

*Re: Electromagnetic pulse*

*Ok - you asked - here it is:*

Build your own *<font color="blue">"AFDB"</font>*, complete instructions. It provides protection for various types of electro magnetic waves/pulses/scans.

*<font color="red">And don't forget to post pictures!</font>*


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## highlandsun (Mar 4, 2003)

*Re: Electromagnetic pulse*

Once again, our buddies at Information Unlimited come through...

http://www.amazing1.com/emp.htm

A bit expensive for the pre-made units. But I would love to see how it works on a composite-bodied car, say a Saturn or Corvette...


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## AlphaTea (Mar 4, 2003)

*Re: Electromagnetic pulse*

IIRC Popular Science magazine had an article last year about a "cheap" EMP weapon that almost any country could make from easily obtainable electrical/mechanical parts (non-nuclear).

As far as your home microwave goes, dont make the mistake of putting ANY kind of recycled paper in there. Some Eco-nuts like recycled paper towels. I have seen it ignite within seconds. It seems that in the recycle process they are still not able to remove all traces of metal (i.e. aluminum foil gum wrappers etc).

Hmmm...I wonder where recycled toilet paper comes from?


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## LEDmodMan (Mar 4, 2003)

*Re: Electromagnetic pulse*

So I wonder if those silver ESD bags we're all familiar with would protect from a device from EMP? They protect from static, why not EM? When I used to work for an electronics company, I was amazed at what kind of damage a static shock could cause to an IC. When the ones with the clear windows in them were damaged (usually these are EPROMS), you could looks at them under a microscope, and there were marks on the chip that looked like it had been through world war 3! Pieces of it blown apart!! While LEDs aren't as sensitive to static charges as some other things, a large charge can still damage them, so make sure to follow ESD procedures when you get your packages in the mail! Yes, it does feel/look stupid to be wearing a bracelet that is plugged into the ground of a wall socket, but that will pay for itself eventually.


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## Entropy (Mar 4, 2003)

*Re: Electromagnetic pulse*

[ QUOTE ]
*Minjin said:*
Oh come on...everyone's dying to ask the one question that is burning on our minds: How do we make an EMP device? /ubbthreads/images/graemlins/wink.gif

After all, isn't this the Electronics and Other Mad Scientist Projects forum? Reminiscent of the scene in Cryptonomicon where they activate an EMP device in the back of a van...

Oh yeah, anyone ever hear the old trick of tying a knot in a power cord to prevent damage if lightning should strike? /ubbthreads/images/graemlins/smile.gif


Mark 

[/ QUOTE ]
Tying a knot in a power cord might help a bit - This will add inductance to the cord, which will increase the impedance to high-frequency spikes. Probably not enough to make a difference except in marginal situations.

As to making an EMP device - Certain configurations of the human body and a Van De Graaf generator can result in some nice pulses going through the body. I recall once in high school physics, we did something that involved a ring of people with either one or both ends at the VDG. If the ring was interrupted (or possibly if it was closed by a person at the other end touching ground), a jolt would go through everyone that could be felt. We were told to remove any watches beforehand. One guy forgot to do so and his watch didn't survive the day!

As to whether a light being EDCed would survive - Probably quite a bit of luck involved. Something like a MiniMag has shielding over most of its body, which would offer some protection. Wrapping it well in aluminum foil would work, so would putting it into a metal box or can (think Faraday cage) for safety. Key being that the box would have no holes/wires going in/out when closed. A "thin" solution might be a copper pipe with an endcap soldered on one end, and a threaded joint on the other so you can screw the other cap on. 

Shankus - As far as shielding needing a path to ground, this isn't true. It's a known fact in physics that electrical fields to not pass into a good conductor. Best example is a solid ball - There will be an electrical field on the surface of a charged ball, but none inside. This can be extended to a hollow ball - Same thing. Electrical field outside, none inside. Any sealed metal container has the same effect.

Also, even nonsealed containers work well up to a given frequency (where the holes in the container are greater than the wavelength at that frequency). A cage made of window screening will block any electromagnetic energy below the high microwave region from getting in. A good example of a Faraday cage are some demonstrations people have done with huge Van De Graaf generators or Tesla coils - A person standing inside a cage getting struck by arcs of electricity from such sources will feel NOTHING. (At least not directly from the electricity - The sound of the arcs would be a different story.)


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## shipinretech (Mar 4, 2003)

*Re: Electromagnetic pulse*

Your first concern in any weapon of mass destruction event is proximity. The most important decisions you made about surviving a massively destructive event is where you live and where you work. If you live or work in a high risk area, you and your electronics are substantially more vulnerable to EMP pulse and everything else, because you are more likely to be in close proximity to a massively destructive event. 

In instances of EMP, and every other kind of point source destructive event, the effect generally tends to follow the laws of spherical spreading loss. This is good news because the power of the destructive wave fronts are inverse cubes of the distance. There are some ground effect, transmission line, and atmospheric anomalies to be considered, but those are practically impossible for the layman to calculate due the immense number of variables involved, starting with the location and composition of the initial event. In short, however, distance from the blast is your best friend. Heading for the hills is also a good idea because terra firma stops everything but cosmic rays. 

Now back in the bad old days of the Cold War when it was not beyond the range of possibility that substantial numbers of nuclear devices would fly at any given moment, the likelihood of being caught in an EMP pulse was pretty substantial and wildly irrelevant. If you were caught by an EMP pulse, you were probably about to be in hell anyway because the infrastructure of your city just went up in smoke. Today it is much more likely that if you are caught in an EMP blast, you are going to make it because most of the barbarians and dictators striving for nuclear devices do not have the capability of delivering the repeated strikes necessary to turn your bad day into your last day. Individual nuclear weapons are not nearly as overwhelmingly powerful as movies and anti-war activists would have have you believe. Don't get me wrong, they are not something I want set off anywhere near me, but getting caught in an EMP pulse is not your death warrant. 

It is a good and worthwhile thing to create and maintain an emergency kit and plan. Keeping that kit in an old 20mm ammunition can will probably keep everything dry and EMP proof. I suspect that aluminum Mag Instruments based lights will probably hold up much better than plastic bodied flashlights. I very much hope that I never find out the hard way. I think it can be stated without contradiction that the more parts, the greater likelihood of part failure by definition.


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## Wylie (Mar 4, 2003)

*Re: Electromagnetic pulse*

Sigman,
That was a funny website. Maybe I should get some of those beanies made with earmuffs for cell phone users. /ubbthreads/images/graemlins/yellowlaugh.gif

Minjin,
From what I have gathered magnetrons are being used now to make EMPs. I am only guessing but magnetrons may also be also in the interruption of transmitting devices used for weaponry. Some people have suggested that magnetrons have been the cause of crop circles. Something about the age of the technologies and the possible advancements and uses as a star wars type of application, kind of has me wondering if this could be true.


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## shankus (Mar 5, 2003)

*Re: Electromagnetic pulse*

Here is a couple of interesting excerpts from this document:

“…thickness plays an important role in shielding. When skin depth is considered, however, it turns out that thickness is only critical at low frequencies. At high frequencies, even metal foils are effective shields.”

“The amount of current flow at any depth in the shield, and the rate of decay is governed by the conductivity of the metal and its permeability. The residual current appearing on the opposite face is the one responsible for generating the field which exists on the other side.”

Of course, what we're talking about, is NO frequency.

http://www.chomerics.com/products/documents/emicat/pg192theory_of_emi.pdf


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## highlandsun (Mar 5, 2003)

*Re: Electromagnetic pulse*

Getting into the mad scientist rhythm of things here... Most of the docs I can find on the subject are about EMP bombs, single-use devices designed to take out a large area. I just want a small focused gun that will let me take out my annoying neighbor's boombox when it's keeping me awake. How much power could that possibly require... I bet the starter from my HID headlight kit could be a good first approach, and the parabolic reflector of the headlamp housing itself is probably decent for aiming purposes...


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## T-Rex (Mar 5, 2003)

*Re: Electromagnetic pulse*

Highlandsun...

That's a good idea. While you're at it, put enough power in to disable a car stereo. Then it can be used for those people who are into major noise pollution. (both from the stereo & engine)


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## PsycoBob[Q2] (Mar 5, 2003)

*Re: Electromagnetic pulse*

www.4hv.org

The TRUE High-Voltage maniacs. /ubbthreads/images/graemlins/buttrock.gif /ubbthreads/images/graemlins/bowdown.gif


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## Gransee (Mar 5, 2003)

*Re: Electromagnetic pulse*

A Post about placing flashlights in a microwave to determine their relative EMP resistance.

Peter


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## PsycoBob[Q2] (Mar 6, 2003)

*Re: Electromagnetic pulse*

Sorry, I'm not gonna nuke my BadBoy.

Course, if Craig wants top add that to the drop-tests.... /ubbthreads/images/graemlins/help.gif


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## Marshall Johnson (Mar 6, 2003)

*Re: Electromagnetic pulse*

[ QUOTE ]
*shipinretech said:*
Individual nuclear weapons are not nearly as overwhelmingly powerful as movies and anti-war activists would have have you believe. 

[/ QUOTE ]

I'll agree here. It seems that movies have convinced people that if a nuke went off in the country, that half a state would be vaporised. But this isn't the case. Hundreds of nukes used to be tested outside of Las Vegas and they even used to hand out goggles so people could watch!

Sure, if detonated in a city it would cause massive damage, but it's not going to send your whole state up in smoke.


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## Marshall Johnson (Mar 6, 2003)

*Re: Electromagnetic pulse*

[ QUOTE ]
*Wylie said:*
Some people have suggested that magnetrons have been the cause of crop circles. Something about the age of the technologies and the possible advancements 

[/ QUOTE ]

Other people have suggested that THEY have made crop circles. Something about stepping on the corn with their feet and fooling conspiracy theorists for decades.


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## Kirill (Mar 6, 2003)

*Some words from army engineer...*

In common case, all devices with semiconductor elements can be damaged by EMI (Elecromagnetic Impulse - correct name for it). For military use, devices has different protective classes (I think, it's same situation in every country), some of devices can work right after nuclear blast at 1-2 kilometers from them. But such devices are made without semiconductors - there are compact variants of old-time electronic lamps (they can't be damaged by internal current, produced by EMI and they are insensitive to high gamma-radiation). Most devices with semiconductors has to be in solid metal screens, because every element is connected to circuit board or wires (working like antennas in such case), and strong EMI can produce high frequency current in it.
If we are talking about flashlights with LEDs or internal electronics, it's "protection class" depends only on two things: does flashlight has solid metal body (like MagLite) and does it have metal cover for lens. If two "yes" - you are lucky, your flashlight can resist EMI (maybe, better than your car with electronic ignition). If only first "yes" - it can resist, but without guarantee. If two "no" - it's better to take another, if you want to face nuclear war with light. 8) I think, only SureFire produces good LED flashlights for this.


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## Lux Luthor (Mar 6, 2003)

*Re: Some words from army engineer...*

Kirill,

What about a metal bodied flashlight with an LED using a grounded aluminum reflector? This should protect the circuitry, but the LED would be more exposed. Do you think the LED is more or less sensitive to EMI than the typical driving circuitry?


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## Kirill (Mar 7, 2003)

*Re: Some words from army engineer...*

In real practice, it can be really hard to calculate, how effective is metal screen with some required holes. Generally, small hole (~1/5" or 0.5 cm) is not a big problem (most of screened devices has ventilation holes like this or little less diameter). And I don't think, that if you will be in nearest zone of nuclear blast, broken flashlight will be the greatest problem... But if you want to make your best to protect your device, it's better to use metal cap (when flashlight is off) or special cover made of steel grid (1/25" step or less).


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## Silviron (Mar 7, 2003)

*Re: Some words from army engineer...*

Or keep it in a metal ammo can or something similar.


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## Wim Hertog (Mar 7, 2003)

*Re: Electromagnetic pulse*

Making an EMP is very simple: just charge a bunch of very large caps and when they are full, discharge them thru a coil! The larger the current, voltage and coil, the bigger the pulse. You can also use microwave generators...


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## Wylie (Mar 7, 2003)

*Re: Electromagnetic pulse*

Wim Hertog,
There you go, now add a magnetically controlled directional impulses through the open center of the magnetron and another around the outside of the magnetron moving in the same direction as the magnet in the center and it seems to make sense to me. The only problem is fitting that much needed electricity into a portable size that is light enough for a human to lift.
Satellites circling the earth would only need to uncoil a faros conductor to generate the electrical current that I would guess would be needed. It is kind of interesting how those guys with the boards out there in the middle of the night generate enough heat to pop the nodes on plants like popcorn now isn’t it. /ubbthreads/images/graemlins/icon3.gif


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## StoneDog (Mar 7, 2003)

*Re: Electromagnetic pulse*

Silviron, I was thinking surplus ammo cans too! Need to make a trip to the local surplus store and pick up a dozen or so, should be handy for safeguarding any emergency equipment/supplies if (and when?) things go south.

Jon


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## donn (Mar 7, 2003)

*Re: Electromagnetic pulse*

Wow! thanks for the physics lessons everybody. Sure came to the right place for answers. Knowing nothing about electronics most of its gone right over my head but like I tell myself I'm here to lurk 'n' learn. 

[ QUOTE ]
*Minjin said:*
Oh come on...everyone's dying to ask the one question that is burning on our minds: How do we make an EMP device? /ubbthreads/images/graemlins/wink.gif

Mark 

[/ QUOTE ]

I remember an article in New Scientist magazine sometime in either 1999 or 2000 detailing how terrorists could build an 'E'-bomb that could fit in the back of a van. If you can track down the issue (soz I cant remember which one) you'll find it there.
Cheers
D.


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## Wim Hertog (Mar 7, 2003)

*Re: Electromagnetic pulse*

I know what's gonna be my next big project...
I already have a few (5) microwave generators and their power supplies (from old MW ovens) 
I don't think it will be portable, but so what!
A friend of mine built a large Tesla coil, sucking 16 000 watts and producing 2m sparks and is it portable? NO! Fun? YES!


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## oldgrandpajack (Oct 4, 2003)

Anyone here know if incandescent bulbs have a better chance of surviving EMP than LED's? What about digitally regulated flashlights and EMP? With North Korea and Pakistan now having developed nuclear devices, I fear this may be an issue in the future. Some well funded terrorist could approach either nation with the intent of purchasing a low yield device that is small enough to sneak across our border. Last I heard, Russia didn't know where all of it's man portable devices were.
oldgrandpajack /ubbthreads/images/graemlins/icon23.gif


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## wwglen (Oct 4, 2003)

*Re: EMP VS. LED*

The major thing that really causes a problem with EMD is long wires. The short leads and switches in a Flashlight would probably not cuse a problem.

Anything attached to power lines would be toast.

After an EMP strike Batteries would be hard to replace so the long run time on the small LED lights would be perfect.

If you are still concerned place a couple of small cheap LED lights in an Ammo Box. Something like a Rebel "AA", and a $7.00 Wal-Mart "AAA" headlamp would be great.

Humm... Now I know what to do with my Rebel.

Alss a small bag of various LEDs, resistors and some wire wrapping tools would allow you to build adaptors for your other lights.


wwglen


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## js (Oct 4, 2003)

*Re: EMP VS. LED*

oldgrandpajack,

I'm no expert in EMP and it's effects, but from what I remember from my Nuclear Physics text book and its very morbidly fascinating chapters on nuclear weapons, I would say that LEDs would definitely be affected as well as all other electronics based on silicone semiconductor technology (i.e. diodes, transistors, op amps, MOSFETs, etc). Also, given that vacuum tubes, which have filaments, are reported to survive an EMP I would say that unregulated incandescent lights will also survive, but I'm not sure.

Here's a bit of trivia for you. If you take the total equivalent mega-tonnage of TNT that the USA and former USSR possess in nuclear weapons, and divide by the number of people living on the planet, you get one cubic METER of TNT for each person. Each of us has an associated cubic meter of high explosives allotted to us from the plenitude of the nuclear arsenal.


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## js (Oct 4, 2003)

*Re: EMP VS. LED*

wwglen,

An ammo case will not protect interior components from an EMP from a nuclear weapon. It would have to be a whole lot thicker than that. Here's an example: we have some fast pulsed electro-magnets here at the accelerator, and just recently we found that stray fields from one of them were affecting the stored particle beam. The shielding copper near the beam pipe had to be *3/8 inch thick!*. I can assure you that the electromagnetic discharge from a nuclear fission/fussion bomb will be many orders of magnitude greater than from our whimpy pulsed magnet.

Unless of course your ammo case is super conducting /ubbthreads/images/graemlins/smile.gif . Otherwise you must calculate a "skin depth" of the field into the metal conductor (due to its resistance, i.e. to it's not being a perfect conductor), and then you must make the metal thicker than that in order to effectively shield the interior from all fields. I'm guessing you'd have to make one thick ammo case.


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## mattheww50 (Oct 4, 2003)

*Re: EMP VS. LED*

Actually a lot of things attached power lines are not likely to be bothered much at all. Anything with an transformer on the input side is probably safe. At the frequencies involved with EMP, the transformer is huge brick wall. This is demonstrated almost every day everywhere in the world. EMP is very much like induced voltages from a lightening strike. The instantanous power is huge, but the total energy is very small. A direct lightning strike is another matter, there the instataneous power is huge, and the energy is huge. Direct strikes do a lot of damage, induced voltages tend not to do much damage, even though the induced voltages in a power transmission line my be as much as 100Kv...


EMP tends to be a problem only with high density devices. You get very high instantaneous power, but relatively little energy. This is why for example, Vacuum tube devices are pretty much immune to EMP damage, they have large energy dissipation areas. My gut feel is that devices such as 1 watt + led's are not likely to be damaged. Just not enough energy delivered.

The bind is you take something like a transitor on an IC, which is a 1 micron feature for example. You hit it with an induced voltage of 50 volts, and the characterisitic line impedance which determines the EMP current is probably in the 50-70 ohm range, so you deliver say 50 volts at 1 amp for 1 micro second. Total delivered energey is 50 microjoules. Not much until you realize it was delivered to a device an area of about 1 billonth of a square inch. Energy density= 50,000 joules per square inch. Instant toast. Apply that same energy to MOSFET device, and the 50V part will simply punch a hole in the gate, also toast. Apply to a high power bipolar device, or for example a 1 watt LED, and it is still 50 microwatts, but say the feature size is now .1 inches, that is 50 microjoules spead of .01 square inches,
of that is 5 millijoules per square inch. You can raise that 50 volts to even 5000 volts (.5 joules, 1/2 watt for 1 second), and It isn't even going to get very warm. EMP is deadly against low power, and MOS devices, it just isn't a big hazard for higher power devices, it is more of a nuisance. 

There is practical experience to back this up. In the early 1960's several tests were carried out in space, the largest was roughly 1.5 Megatons. It caused considerable havoc in the telphone system in Hawaii, and it caused power outages. the power outages were a result of the induced currents in the transmission network being sufficient to trip circuit breakers. (although it took a while for any to realize that the telephone and power network problems in the Hawaiian islands were EMP effects). There was damage to the telephone solid state gear, but at the time, much of it was still electromechanical, and that stuff, plus the older telephone (rotary dial), the older stuff escapced undamaged.

A similar induced current lead to one of the major blackouts in the 1970's in the eastern United States when a breaker in Canada tripped because of an geo magnetic storm(auroral) induced current added to the AC current in the transmission circuits.

The bottom line is that for the most part only low power, small feature devices, and insulated gate devices such as MOS technology, tend to be damaged by EMP. The larger featured, high power devices can usually dissipate the energy. The instantaneous power is very high, but the actualy energy delivered is very modest. So things like computer memories, 5mm LED's, CPU's etc are toast, your CRT is likely to escape damage.

Oh yes, the skin depth is pretty shallow. The formula for skin depth in copper is 6.6/f^.5 in cm. So at 60Hz it is .85 cm (hence copper wires up to about 1.7cm in diamter work well. Bigger then that, and you should use stranded conductors. at 1Kz it is .21 cm (about 1/100 th of an inch),
at 10 Mhz, 21 microns (about 1/10,000 th of an inch). Now you know why silver plating of high power vacuum tubes, and copper braid for a ground conductor is so attractive.

In short, an ammo box will provide more than adequate EMP protection. EMP sources are in the Mhz range, not Hz, not Khz. The accelerator issue is the wrong problem. The magnets in accelerators provide a uniform field, they are assential DC devices, so skin depth isn't meaningful, it is essentially a DC field.


----------



## js (Oct 4, 2003)

*Re: EMP VS. LED*

matheww50,

Thanks for the info. Sounds like you know what you're talking about. Except not all magnets in an accelerator are DC devices. The magnet I'm talking about is a PULSED magnet. The idea is to give the beam coming into the storage ring (the injected bunch) a magnetic kick, but one that dies off before the stored bunch of particles comes along. It is a fast two or three turn magnet, so the inductance is relatively low. It pulses on and then off and is carefully timed.

I would never have guessed it, but from what you say, our pulsed septum is MUCH more powerful than the EMP from a nuclear bomb. Imagine that.

So if all it takes is a metal box and a transformer on the input power to resist EMP, why was the military so worried about EMP? Isn't most electronic equipment in a metal box? Or at least, most of the MILITARY electronic equipment?


----------



## js (Oct 4, 2003)

*Re: EMP VS. LED*

matheww50,

BTW, I don't think that the skin depth formula you gave is valid for a pulse. I think that's only valid for sinusoidal AC power. Maybe I'm wrong. Also, how do you know the frequency of the EMP? Doesn't a non-sinusoidal wave have many frequencies, in fact, infinite frequencies. The fourier transform of a delta function is ALL frequencies weighted equally. Err. Or is it that all EM energy travels as a wave of a certain frequency. Geez, I am RUSTY. Thanks for any light you can shed on the subject.


----------



## James S (Oct 4, 2003)

*Re: EMP VS. LED*

wow, this is why I love this place, so much fascinating info! Thanks guys, now js I want to know more about your project too /ubbthreads/images/graemlins/smile.gif

As far as boxes, yes they are great if they are sealed, however, most equipment is connected to other quipment via long wires. This is why they are concerned. If you could seal everything in a metal box it's OK, but if it's actually in use and connected it's toast as it will travel right through the wires and inside the box.


----------



## Double_A (Oct 5, 2003)

*Re: EMP VS. LED*

OK, forgive my ignorance, but wouldn't the inverse square law reduce power levels to the point where if you had induced currents sufficient to cause damage in a shielded container, your flashlights would be the last thing to worry about?

GregR

P.S. Please continue the discussion I find it very interesting!


----------



## Tomas (Oct 5, 2003)

*Re: EMP VS. LED*

Most electronic devices, even military, have leads other than power leads that penetrate the sheilding - antennas, sensor leads, output devices, etc.

This is often what causes the EMP protection engineers heartburn. Any lead that penetrates the shield is, uh, an antenna for EMP, and once conducted inside the shield it nicely toasts any toastable 'thingies' inside.





/ubbthreads/images/graemlins/ooo.gif


----------



## The_LED_Museum (Oct 5, 2003)

*Re: EMP VS. LEDs and Incandescent bulbs.*

From what I know, an EMP from a nuclear bomb detonated in the atmosphere can generate as much as 50,000 volts per meter (or was that per foot?) of wire. Nothing I'd want to screw with. /ubbthreads/images/graemlins/eek.gif
Metal-bodied flashlights like the Arc might be alright, but plastic-bodied flashlights will probably go bye bye. /ubbthreads/images/graemlins/icon15.gif 
So if you have an eternaLight or a Lightwave 3000, it's a pretty good bet they'll be fried. /ubbthreads/images/graemlins/frown.gif /ubbthreads/images/graemlins/jpshakehead.gif /ubbthreads/images/graemlins/frown.gif


----------



## Double_A (Oct 5, 2003)

*Re: EMP VS. LED*

Tomas-

Your statement is consistant with everything I've read. Protective measures I've heard have suggested nothing more need to be done than disconnect external conductive feed ins and secure the main electronic unit in a metal box. Of course that only works if you anticipate a nuke blast. 

And of course, if you survived an initial blast and hooked up batteries, antennas etc. and they hit with a second or subsequent nukes you'd be screwed. oh well.

GregR


----------



## js (Oct 5, 2003)

*Re: EMP VS. LED*

OK, for all who are interested, I've done a little research on skin depth and EMP from a nuclear weapon.

Here is what my Nuclear Physics text says about an EMP from a nuclear bomb:

"The prompt gama rays and X rays released in the explosion interact with air molecules (through Compton scattering and ionization) to create a large current of negative electrons flowing outward from the point of the explosion. These electrons are accelerated by the Earth's magnetic field and give rise to a traveling electromagnetic wave in the form of a pulse. An explosion several hundred kilometers above the center of the United States would be within the line of sight of the entire United States and would expose the country to electric fields of the order of 10000 Volts per Meter for a 1 megaton blast. Such a pulse could be destructive of electrical power networks and communications grids."

Thus, the EMP pulse is not mono-chromatic, and, and as travelling EM packet, or pulse, will be composed of a large range of frequencies.

Second, the skin depth equation given by matheww50 assumes that the conductivity, sigma, is much much larger (and constant) than the product of the frequency of the (mono chromatic) EM wave and the permitivity of the material in which it is travelling, and also that the permitivity, epsilon, is also constant. These assumptions do not hold good in the case of an EMP. It's all rather complicated and I would need quite a bit more time to research it.

But the important point is that, as matheww50 suggests, skin depth is not really the way to get a handle on the effects of an EMP. As mentioned by others above, a metal box with no "antennas" sticking out of it should protect the interior electronics from damage. At least that's the impression I've gotten so far.

Yet, almost all electronics are connected together by wires, and these wires will transmit the EMP energy to sensitive elements and pfffoomp! they're toast. Optical cable. That's the answer!

So back to the original question: It would appear so far, that the verdict is that metal LED lights and incandescent lights and any lights in a metal box, will all be good to go after a nuclear war. Except those too close to ground zero. /ubbthreads/images/graemlins/smile.gif

And that's another thing. There's more to a nuclear detonation than the EMP. All sorts of radiation comes your way, and makes life hard to live, and probably does bad things to electronics. I know that here at Cornell's accelerator (CESR) ( www.lns.cornell.edu for those who are interested) we have plenty of electronics in the ring (where the beam goes round, which creates hard X rays) and we often have problems with electronics failing due to radiation damage, even with copper and lead shielding, and beyond that, neutron radiation from a nuclear bomb is really bad news, though mostly for living things. Any electronics that gets too much of this direct radiation will be toast, but I would think that it'd have to be within a kilometer of the detonation point. Just guessing, though.

Ah yes, all of that is so very cheering, isn't it?


----------



## Double_A (Oct 5, 2003)

*Re: EMP VS. LED*

Jim S-

Your remark on optical cables being immune to picking up an electrical charge, reminded me of a news story I read back during the first Desert Storm conflict. Apparently some people were surprised to find out Sadam had all of his underground facilities self sustaining and self contained (water, Air Purification, electrical generation etc. The only thing connecting them together were fiber optic cables immune to EMP.

Have a nice Day, a'll
GregR


----------



## mattheww50 (Oct 6, 2003)

*Re: EMP VS. LED*

A magnet has a huge inductance, so even a pulsed magnet is unlikely to operate at a frequency of more than a few Khz, the same skin depth that limits the effect of the pulse, also limits the current you can supply to the magnet. You use very high voltages on the magnets to overcome the huge inductances, but you are still looking at rise times measured in tens of microseconds usually.

I had a customer in CTR8 at Los Alamos years ago. That was the magnetic confinement Nuclear fusion research, All of the connections from the experiements to the computer and control equipment were fiber optic, but the electronics was housed inside a room with about 1/16th inch copper walls, and carefully build sealing doors with huge conducting surfaces to the walls. The 1/16th of an inch was more than adequate to prevent the pulsed magnets used from causing any problems with the electronics via induced voltages.

As as for Radiation damage, most MOS devices are subject to radiation damage, however you will be 'cooked' long before most of those devices are serious damaged. They are a lot more radiation resistant then you are. Most are good for something on the of the 10 Kilorads. .5 Kilrads is roughly LD50 for humans.


----------



## js (Oct 6, 2003)

*Re: EMP VS. LED*

matheww50,

I'm sorry to have to disagree with you again, but our pulsed magnet septum is a single or double turn magnet with a turn on to turn off time of 50 micro seconds. I would guess that the rise time is as you suggest, around 10 mircoseconds or less. The inductance is NOT huge. At least compared to our quadrapoles and dipoles. As for the skin depth calculation, I did not do it, nor do I know how it was calculated, but I just talked to the person who did it, JUST NOW, and he said that the copper plate needed to be 1/4 inch thick. So I was wrong when I said 3/8, but not all that far off.

Some of the top scientists and engineers in THE WORLD work here at the lab (I'm not one of them, obviously) and I can assure you that they know how to calculate a skin depth. It is obviously more complicated than you realize, because stray fields were in fact disturbing the stored beams before the extra shielding, and are not now doing so after the extra shielding. Something in your understanding of the theory, or in your understanding of our situation (no doubt due to my poor understanding and communication of these things) has to be amiss.

But really, I suppose it's not all that important because you are right on about all the rest of it. Oh, and BTW, our gun filament and HV power supply (where the electrons start out their lives) are encased in just such a carefully sealed metal cage as you describe, with fiber optic connections going into it, and a ceramic piece to connect the vacuum chambers together, and the metal is on the order of 1/16 of an inch thick.

Please forgive me if I have been unnecessarily argumentative, but I'm not making up the whole thick copper shielding thing. It's for real.


----------



## js (Oct 6, 2003)

*Re: EMP VS. LED*

mattheww50,

OK. I just talked to one of the people. The septum turns on every 1/60 of a second with a 50 micro second width half sine wave. Thus, the frequency is nominally 10kHz with 60 Hz side bands. They wanted at least six skin depths of copper. Mike took me through a back of the envelope quick calculation, and six skin depths turns out to be about 1/8 of an inch, BUT he said that the person he was working with used a different formula. However that may be, the shielding needs to be fairly ridgid over the distance of the septum, and lacking any braces to stiffen it, they went with 1/4 inch thick copper. It's overkill on the skin depth front, he told me, but that wasn't the only consideration.

So you're right about the skin depth. I'll just go away now and sit quietly. A little knowledge is dangerous, I guess /ubbthreads/images/graemlins/smile.gif


----------



## Tomas (Oct 7, 2003)

*Re: EMP VS. LED*

This sort of in-depth discussion is one of the really neat things about the inhabitants of CPF's caves. There are enough people with information on some very arcane topics, and that further know others they can ask questions of if they are unsure, that few topics get left drifting. /ubbthreads/images/graemlins/smile.gif 

All I know is when I was working 'round nucs, if my badge turned black it was bad ... /ubbthreads/images/graemlins/ooo.gif 





/ubbthreads/images/graemlins/popcorn.gif


----------



## mattheww50 (Oct 7, 2003)

*Re: EMP VS. LED*

Skin depth is not quite the see and end all. All of the current is not in skin depth. the skin depth is the point at which the current density in the conductor is 1-1/e of what it on the surface, or about 36%. So if you have a field that is on the order of 10,000 volts per meter, and you need to get it down to a few volts per meter, it is going to take several skin depths. For example 6 skin depths will give you about a 400:1 reduction in field strength, and for most everyday applications, that is more than enough, but when you start talking about extreme fields like 10,000 volts per meter, it may not be enough. 8 skin depths give you about 3000:1 shielding, and to cover conductivity issues at bonds and junctions, you may want to a little further, so in a very ugly EMI envirornment, a shield that is 10 skin depths thick is simply realistic. Fortunately at realistic frequencies, that is rarely more than a few millimeters of copper.

It does have some interesting applications however. As a radio amateur, I used to make my antenna's out of copperweld wire. That was copper over a steel core. You got the strength of steel in the wire, and the mm or so of copper on the surface at few Mhz gave the wire conductivity that looked like pure copper. So you get the stength of steel (needed on a 80 meter half wave dipole), and the conductivity of copper.

My late father, held a number of patents on Klystron tubes, they used to make them with silver plated cavities, the skin depth at a few Ghz. 5 Microns of silver was several times the skin depth!


----------



## js (Oct 7, 2003)

*Re: EMP VS. LED*

mattheww50,

Neat! Thanks for the info. We have a bunch of klystrons here at CESR. I didn't know what a klystron even was until I started working here.

Thanks again.


----------



## raggie33 (Oct 7, 2003)

*Re: EMP VS. LED*

hell aint that what happens after a nuke bomb?hect with that im not a suicadal type but after a nuke hit id end my own life no way id suffer


----------



## Ratus (Oct 14, 2003)

*Re: EMP VS. LED*

I just found a great siteabout EMP


----------



## V8TOYTRUCK (Dec 11, 2003)

*Digital Regulation and EMP*

I was sitting in Geology class today and wondered. ''What would happen to my Surefires and ARC if there was an Electromagnetic pulse?'' Would my non regulated Maglites still work and my Surefires would just turn into HAIII paper weights?


----------



## louie (Dec 11, 2003)

*Re: Digital Regulation and EMP*

Peter Gransee posted in the Arc forum that they do test for EMP, and suggested doing a search for "microwave"! He said there is no problem. Do a search for emp in the Arc forum in the last couple of months.


----------



## JackBlades (Dec 11, 2003)

*Re: Digital Regulation and EMP*

An EMP of significance would likely be an after-effect of a nuclear weapons exchange. If your light still functions, you will see only dust.


----------



## js (Dec 11, 2003)

*Re: Digital Regulation and EMP*

Do a search on EMP in this forum as well, as there was an extensive discussion.

Jackblades,

The effect of an EMP extends far beyond the blast radius, and would take down power distribution--to name only one thing--across the entire USA from only one strategic nuke detonated at the right location. Anything with cabling is vulnerable, although input transformers are said to be a complete protection against this.

The short of it, as I have gathered from past discusisons, is that our flashlights will probably all be fine and will be the least of our worries. But if you are concerned, throw a couple in a metal box for safe keeping. Also, all of the Arc lights should be fine, as Peter has tested them in a microwave and they are proof against an EMP.

Anyway, do a search on "EMP" as this has been discussed before.


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## DavidTHR (Mar 7, 2005)

*Flashlights On 24 and Electromagnetic Pulse Bomb ?*

Tonight's 24 episode featured at least two scenes "starring" flashlights (if I recall properly).

One flashlight used by the "bad" Security Director with his weapon while he conducted a search, and the other flashlight was taken off the duty belt of one of the "bad" security guards by Jack Bauer himself.

Can anyone ID either or both of the flashlights used in tonight's (02/07/05) episode of 24?

/ubbthreads/images/graemlins/confused.gif /ubbthreads/images/graemlins/grin.gif /ubbthreads/images/graemlins/confused.gif

P.S. The reason flashlights were being used is that an "electromagnetic pulse bomb" was set-off, and therefore it shutdown all the power, etc.

*** My question: In reality (as opposed to TV), would an "electromagnetic pulse bomb" also render battery operated flashlights useless as well or would they work as normal? ***

/ubbthreads/images/graemlins/ooo.gif /ubbthreads/images/graemlins/confused.gif /ubbthreads/images/graemlins/ooo.gif


----------



## js (Mar 7, 2005)

*Re: Flashlights On 24 and Electromagnetic Pulse Bomb ?*

DavidTHR,

They were TigerLight gold system rechargeable flashlights.

And no, an EMP would not render them useless. No electronic circuits. No LED's. /ubbthreads/images/graemlins/icon15.gif /ubbthreads/images/graemlins/nana.gif


----------



## beezaur (Mar 7, 2005)

*Re: Flashlights On 24 and Electromagnetic Pulse Bo*

A severe EMP might blow a bulb installed in a light, depending on the geometry of the light and how effective it was at being an antenna. I would think that you'd have a pretty darn hard time blowing a spare bulb though.

Usually EMPs are considered to give wavelengths in the mm to cm range. If your flashlight is metal, and the reflector is also metal, the inside of the light should be reasonably well protected.

I am extrapolating from what I know about protecting facilities from lightning and military EMPs, which isn't a lot. Take me with a grain of salt. /ubbthreads/images/graemlins/wink.gif

If you are interested, this example is a good read:

" Engineering and Design - Electromagnetic Pulse (EMP) and Tempest Protection for Facilities"

http://www.usace.army.mil/usace-docs/eng-pamphlets/ep1110-3-2/toc.htm

Scott


----------



## gorlank (Mar 7, 2005)

*Re: Flashlights On 24 and Electromagnetic Pulse Bo*

Thanks for the info, they sure pick some relatively obscure equipment. Great show, I'm waiting for Jack to pull out a Q III and really make my day.


----------



## neogoon (Mar 8, 2005)

*Re: Flashlights On 24 and *spoiler removed**

[ QUOTE ]
*DavidTHR said:*
P.S. The reason flashlights were being used is that an [redacted] was set-off, and therefore it shutdown all the power, etc.


[/ QUOTE ]
A request to please not post plot spoilers for 24 or any other show in the message header for those of us who have taped or tivo'd the show (not to mention our friends on the West Coast)...


----------



## GuyZero (May 25, 2005)

*LEDs and EMPs*

Before I let all of incandescent flashlights get lost... I'm curious; will an LED bulb survive an electromagnetic pulse?

I don't want to sound like an apocalyptic nut, but I like to keep my bases covered. It would suck to be the flashlight geek on the block and be totally in the dark should the "Dark Angel" TV show come to life. /ubbthreads/images/graemlins/wink.gif

Plus I've heard a lot of military vehicles have an second, coil starter for the same possibility.

-Brian


----------



## js (May 25, 2005)

*Re: LEDs and EMPs*

There was a lot of discussion about this in the CAFE at one point, and also in the Arc forum, IIRC. And, at the time, the upshot was that most metal LED flashlights would be OK, but that was before the advent of the Arc4 uC controlled type lights, such as the LH or HDS lights. Someone better informed than myself will need to give a definitive answer here, but if you're worried about it, throw a backup light in a closed metal box, and it will be proof against an EMP, or so I was told by someone in that CAFE thread. I think the main deal with an EMP being so destructive is that anything with a cord or long-ish wire attached will become an antenna and will collect and channel the EMP into the electronics. Thus an EMP would take out the countries power distribution network, I suspect. But an LED flashlight doesn't have a power cord or antenna, so it isn't obvious to me that it would get fried, especially given that it is mostly enclosed by metal.

Still, I was told in school that any solid-state electronic devices would cease to function in the event of a nuclear war--but as we all know, not everything we're told in school is true. /ubbthreads/images/graemlins/icon15.gif

And as an additional bit of info, I know that Peter Gransee tested the Arc AAA and LS models in a micro-wave oven for 30 seconds or something like that, and they came out unscathed. Leave it to Arc to do the EXTREME testing. LOL.


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## The_LED_Museum (May 25, 2005)

*Re: LEDs and EMPs*

LEDs themselves would probably not fare well following an EMP, but a metal-bodied flashlight might offer sufficient shielding to the LED(s) in them that they should survive an EMP.

As far as I'm aware, EMP would create a 50,000 volt charge per meter (~3 feet) of wire or other metallic articles.

An LED flashlight should survive fine if it has an all-metal body, and it is positioned in such a way that the LED(s) itself (themselves) is (are) not aimed directly in the direction of the pulse. The metal body would absorb all of the energy, and transmit none of it to the LED(s).

Just my 2¢ here; individual results and opinions may vary.


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## AJ_Dual (May 26, 2005)

*Re: LEDs and EMPs*

I understand that the damage EMP causes in electronics is induced current in metal bodies from the gigantic RF spike from the detonation of a nuclear device. (Or now, purpose built "E-bombs" that use conventional explosives crushing charged coils to create EMP) Long skinny things like antennas and wires, whether for power or communication are the most supceptible.

It makes sense that the metal bodied flashlights would provide some EMP protection, but… How many lights use their metal bodes as part of the current path? For instance, just about any LED [email protected] conversion, would that be vulnerable? Only if it were on? Could it jump a switch gap if it were small enough? What about the digital lights where the "switch" is really just a gate arrangment in an IC? 

If we take LED Museum's 50kV per meter of antenna metal figure, (The inverse square law and the distance from the detonation would have to change that, but keep it simple for the sake of argument…)what's a reasonable average amperage on that? It can't be much, or we'd be hearing warnings about people being killed by proximity to metal objects during EMP blasts, but instead, all concern and study seems geared twoard electronics.

ESD (electrostatic discharge) can theroretically damage LED's and driver circuitry. It's not even close to 50kV, but on a really good dry day, under ideal conditions like shuffling on shag rug with cheap shoes, you could produce a healthy zap up to around 12kV. Has anybody here actually ever "killed" any LED with ESD? It's far from an exact comparison to an EMP test, but that might provide some interesting insights as to what's possible.

I also think it matters how complex the driver circuitry is. If it's one of the fancier lgihts that use higer end IC logic for tons of dimming and strobe modes it might be more supceptible. If the light is driect drive, only the LED itself is at risk. I've never heard of EMP affecting small portable batteries.

I've got no math to back it up, but my gut is trying to tell me that unless it's laying on a power line, a railroad track, or some other large metal structure that's going to gather lots of induced voltage, you'd have to be close enough to the detonation for blast and thermal effects to make you such a crispy critter that worrying about your LED light is kind of irrelavant. OTOH, the fact that ESD can screw up LED's makes me wonder if packing away an incan or twenty might not be a bad idea for "The Day After".


----------



## idleprocess (May 26, 2005)

*Re: LEDs and EMPs*

I'm not sure that an EMP would hurt the electrical grid too much.

Generators are probably going to be fine - they're mechanically and electrically stout.

The lines would be OK - only a tremendous current surge enough to melt them would kill.

I hear about enough transformer fires to suspect that transformers and distribution equipment might fare worse, since they often have flammable oil within and a voltage surge might cause arcing or somehow ignite it.

Equipment connected to the grid... well, most of it is low-voltage and there's the fact that long wires act as antennae...


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## VidPro (May 27, 2005)

*Re: LEDs and EMPs*

mabey the better question becomes, if the metal body flashlight with the led is effected, will I still be alive enough to care about it 
they say emp is overrated, weak low voltage logic chips, totally unprotected stuff. anything else and the impact is worse than the emp.
look at all the stuff they made, that one bad surge and its gone. and all the magnetic induction stuff tied to it waiting to deliver it.

that is why run time is so important, after the blast in the next 16 hours of the sun being blackened out, you would want a good light so you can find out where you dropped your skin /ubbthreads/images/graemlins/smile.gif


----------



## dat2zip (Jun 4, 2005)

*Re: Electromagnetic pulse*

ESD or Electrostic discharge has to do with electron build up. Aluminum foil and ESD bags protect against this preventing a voltage or charge to build up on your body, device or other equipment. Your body will get charged like capacitor and when you touch someone else you are discharging the capacitor. The charged voltage potential is usually greater than 2KV.

EMP is a magnetic wave and is immune to shields like Aluminum. You'll need some iron to catch magnetic waves and steel plates or any other material that is magnetic will shield against EMP.

A magnetic field will pass right through aluminum foil. Give it a try with a magnet and your fridge. The magnet will hold the aluminum foil to the fridge with no problems.

As for damage from an EMP pulse. It doesn't take much. The little bond wire connecting the die of the LED will be more than ample to pick up the EMP pulse and generate an induced voltage that will be impressed on the LED. If there is sufficient voltage and power coupled into the little bond wire the LED will fry.

Wayne


----------



## NewBie (Jun 4, 2005)

*Re: Electromagnetic pulse*

A fella should read up on Faraday Cages.

A truly unique room called a Faraday Cage so named in honor of Michael Faraday who in 1831 discovered the principle of magnetic induction, and in 1836 described the Faraday Cage in his diary.

Michael Faraday lived from 1791 to 1867 and is often considered to be the greatest experimentalist in the field of electricity and magnetism. He, along with others (such as Ohm, Volta, Coulomb, etc.) uncovered the relationships between the various experimental phenomena that lie at the
foundation of the field. He championed the concept of magnetic "lines of force" to understand this body of work.

About this time, Reimann and Guass noted the similarity between athe phenomena of electricity and magnetism and that of gravity and were able to quickly borrow the mathematics from celestial mechanics and apply them to electromagnetism. Faraday did not like the approach of these Germans but he was not adept enough at mathematics to challenge their position. So he explained his ideas to a young Scottish mathematician named James Clerk Maxwell.

http://www.boltlightningprotection.com/Elemental_Faraday_Cage.htm

http://www.physlink.com/Education/AskExperts/ae176.cfm


----------



## mattheww50 (Jun 4, 2005)

*Re: Electromagnetic pulse*

We don't think of conductive materials as magnetic shields, because they are not very effective against fixed fields unless they are super conducting.

However the magnetic field going through any conductor will in fact induce currents that will oppose the field. How effective the shield is a function of thick it is relative to the 'skin' depth. At 60Hz, even in copper it is on the order of an inch, so to provide a magnetic sheild from a 60hz field, you would need a copper or aluminum shield several inches thick. However as you go up in frequency, the skin depth goes down as square root of frequency. Suffices to say that by time you get to Gighertz, the skin depth is tiny, and in fact a 1 micron thick silverplate on a waveguide will behave like the waveguide is pure silver. EMP depends upon inducing high voltages with very rapid rise times in the conductor, and the high voltage blows holes in PN junctions and FET devices. However at the frequencies involved, even aluminium foil will make a more than adequate EMP sheild.

A Faraday cage does two things. It creates an equipotential space on the inside, and the magnetic fields it is subjected to induce currents in the cage that generate fields opposite to the applied field, and effective cancel them inside the cage. For this to work however, the cage has to be the thickness of several 'skin' depths. Fortunately once you get beyond power line frequencies this is not hard. While skin depth is about 1.6cm in copper at 60hz, at 600Khz it will be .016cm, or .16mm (a little thicker than aluminum foil) At 60Mhz it will be .016mm
considerably thinner than aluminum foil, in fact a plated on metalic film will work just fine. Many VHF/UHF coaxial cables utilze a shield of metalized plastic. A micron thick film of metal is all it takes!


----------



## HarryN (Jun 5, 2005)

*Re: Electromagnetic pulse*

So my resistored 2x 123 might still be working when those big, bad, inductor based lights are dead - cool.


----------



## NewBie (Jun 5, 2005)

*Re: Electromagnetic pulse*

Actually, a fella should consider that an electromagnetic wave is comprised of both an E field and an M field. If you suppress one, the other doesn't propagate very far.

Thats why a non-ferrous metal, such as aluminum or copper suppresses EMI well. A ferrous metal works better, since it acts on both components of the field.

Try this experiment. Find a long thick sheet of aluminum or copper. Grab a rare earth magnet. Hold the sheet near vertical. Set magnet on surface and let go. You will notice the magnet falls slowly. Even though the sheet is made of a non-magnetic material. This is due to the counter EMF force produced by the eddy currents that are generated as the magnetic field passes through the non-magnetic, but electrically conductive material. The stronger the magnetic field the stronger the counterforce. The more rapidly the magnetic field changes, the stronger the counterforce.

This is why you'll find aluminum and copper still works for EMP protection on military equipment. Additionally, you often find filters and/or protection circuits on any sensitive input and output connections.

So an aluminum bodied flashlight with an aluminum reflector that is well connected to the body, with all the pieces of the body electrically connected as well, actually stands a great chance of surviving a EMP pulse, even with electronics inside.

Non-Metallic flashlights with electronics would be toast.

Of more concern for me would be the radiation, which is known to upset uC and PIC devices which have flash/EEPROM memory which can be erased and/or upset by the radiation burst.


----------



## mattheww50 (Jun 5, 2005)

*Re: Electromagnetic pulse*

Actually if you make the sheet of a super conductor (such as lead at near absolute zero) in the shape of a plate, the magnet will actually float in mid air! The induced voltages in the super conductor created by the moving permanent magnetic induce currents in the super conductor, and the reusltant field opposes the field of the magnet. The magnet will in fact float as long as the plate remains in a super conducting state.


----------



## AC_Doctor (Jul 21, 2005)

*LED flashlight vs. EMP = ???*

With all the talk about smuggled nuked into the US, will my
S*refire LED lights work after an EMP pulse ???


----------



## The_virus (Jul 21, 2005)

*Re: LED flashlight vs. EMP = ???*

I won't claim to be even close to an expert, but from what I know...wouldn't the electonics be unharmed, but your batteries discharged? Or maybe your batteries would discharge into the bulb and blow it...I don't know honestly.

EDIT: Check out the article here about how e-bombs work. There's also links to a wealth of information there on the last page.


----------



## xpitxbullx (Jul 22, 2005)

*Re: LED flashlight vs. EMP = ???*

Flashlights and batteries are fine as long and there are no semi-conductive electronics or microchips in the flashlight.

Jeff


----------



## Double_A (Jul 22, 2005)

*Re: LED flashlight vs. EMP = ???*

I can't directly answer your question, however I believe it would be fine, as would an incandescent lamp.

In the past it has been stated that electrical equipment using semiconductor devices would be ok as long as they weren't connected to lengths of wire (phone lines, power lines, antennas) that would collect EMP energy and feed it back into the gear blowing it out.

After having read an article in IEEE Spectrum about a year and a half ago I'm not so sure with the new EMP generating weapons out there using conventional explosives and collapsing magnetic fields generating EMP's across a wider range of frequencies.


----------



## greenlight (Jul 22, 2005)

*Re: LED flashlight vs. EMP = ???*

But would you survive the blast?


----------



## Sigman (Jul 22, 2005)

*Re: LED flashlight vs. EMP = ???*

Have you been watching "War of the Worlds"?! /ubbthreads/images/graemlins/grin.gif (*<font color="red">"Standby - edit of long link 'hopefully in progress'".)*</font>

I did a search here (menu option at top of page) on "Electromagnetic Pulse" and came up with "this thread" from January 2003 (lots of posts & info), as well as "another one".

After I saw "War of the Worlds" the other day - the same question popped back into my head! "Deja View"! /ubbthreads/images/graemlins/grin.gif

I'll see if we can get this one locked and we can continue those threads. You may find the answers to your questions and it will refresh us as well on those!


----------



## Silviron (Jul 22, 2005)

*Re: LED flashlight vs. EMP = ???*

Ok, With the caveat that it has been 20 years since my last training on EMP and other nuclear battlefield operations ( I was a communications guy for my PMOS in the Army, and had several short courses and seminars on the subject), here is what I know, or think I know about ElectroMagnetic Pulses and electronic equipment:

1: Batteries uneffected * _(unless of course they are vaporized due to proximity to a nuc. blast)_

2: Transistors, ICs and inductors are the most vulnerable electronic components to EMP. Resistors, capacitors, vacuum tubes and straight conductors (on devices not connected to "mains" AC power) are fairly safe at -X- range from the pulse unless other components in the circuit , especially inductors generate enough juice to zap them.
* Protected Lithium Ions are vulnerable, because they have ICs and inductors in them)

3: Bad news for you "hot wire" flashlight fans: You know that coil of tungsten wire that glows when you click the switch or turn the head? Guess what.... for the purposes of an electromagnetric pulse, it IS an inductor and will probably fry /ubbthreads/images/graemlins/frown.gif

4: A simple "Faraday cage" will protect most electronics, including your high tech flashlight _ (we can discuss Faraday cages later, although a search here should turn up some info on them... I think I talked about them in a thread a couple of months ago and posted some links )_.... 

5: Now, here is the good news: Your metal bodied flashlight IS a pretty decent Faraday Cage. Just about the only path that the pulse can take is directly through the lens / optic in front. and if you set it face down on a metal sheet (even a piece of aluminum foil), it will be a darn near perfect Faraday cage in and of itself. /ubbthreads/images/graemlins/smile.gif

6: I'm just making a semi-educated guess here, but I think LEDs in a direct drive and/or carbon resistored** light will be somewhat EMP resistant by themselves, and are PROBABLY more likely to survive than a regular bulb. 
** an EMP will think that a wirewound resistor is an inductor and probably fry it.

7: Just a couple of months ago there was a big furor over Iran threatening to destroy our entire National infrastructure with an EMP weapon set off over Kansas City or someplace central like that. And a WHOLE BUNCH of panicky journalists spent a couple of days hyperventilating about it and trying to scare the ignorant masses:

A: Even if they have the weapon itself, they don't have the means
to deliver it. An EMP device set off at or near ground level
will have VERY limited range.... I doubt that they will be
capable of delivering it even in 10 years unless they contract it
out. 

B: China MIGHT be able do it now and probaby will be able to do
it in a few years due to the secrets that they were given / sold a 
few years ago. Russia could do it now. North Korea might be
able to do it in a couple more years if we don't set them back
SERIOUSLY in the near future, and I fear that they have the
least to lose by doing so.

C: The range of effect of EMP pulses is VASTLY over hyped.
I think that right now, only the USA and POSSIBLY Russia are 
capable of actually shutting down the infrastructure of a
nation the size of the USA..

D: Our electrical grid IS highly vulnerable. Very little redundancy.
We are actually more vulnerable than we were 30 years ago in
that respect. Because everything is interconnected, a hit on
one corner of the country could conceivably bring down the
whole grid for weeks, if not months, until the "experts" figure
out which switches to flip so as to isolate the areas with actual
damage, and free up the areas that could function on their own.

E: Because the electrical system COULD go down nation wide,
you need to be prepared and have the necessities of life
stockpiled. Water, Food, Fuel. Alkaline / Lithium (primary)
batteries, because you won't be able to recharge unless you have 
a "non grid" power source.

F: Even though your local McDonalds, your local Wal-Mart, your
local grocery store COULD sell you supplies, and your bank 
COULD give you your money they won't, because their computer 
systems will be down, and they won't want to screw up
their inventories, and their cashiers, victims of the public education
system, will not even be able to make change without a computer
to tell them how......

Which will, of course lead to looting.

8: And of course the worst thing for us is that the internet and CPF could be down for months.


----------



## Genxsis (Jan 25, 2006)

*Would nuclear EMP hurt LEDs?*

With all the talk about Iran in the news lately, it seems like a good time to prepare for anything now. With a nuke goes off, it produces electromagnetic pulse (EMP) which is supposed to do alot of damage to electronics. Would that also apply to LED bulbs too since they are a semiconductor rather than a filament bulb?

Some things are just nice to know. Let's hope we don't find out! But hypothetically, would it destroy an LED?


----------



## joema (Jan 25, 2006)

*Re: Would nuclear EMP hurt LEDs?*

That's a good question. I don't know the answer but you could try posting it here: http://www.physicsforums.com/index.php


----------



## DCFluX (Jan 25, 2006)

*Re: Would nuclear EMP hurt LEDs?*

I heard someone did some simulated EMP experiments with giant electomagnetic coils and a huge cap bank. The thing that was most consistantly blown up was the first active stage in a radio receiver, tube and transistor.

I would think that the silicon would convert the broadband energy of a nuclear explosion to a voltage, which may be in the mV to single volt range if you hung a voltmeter on it. 

You can use a LED as a crude light detector if you amplify the voltage coming off the leads. Same principle as a "crystal" radio, just different frequencies.

But if this was in a circuit that was shorted at the time of the pulse it may be possible to pop the bonding wires from the silicon to the packages leads. So the silicon would still be good, but it wouldn't be connected to the outside world and would make it useless.


----------



## carrot (Jan 25, 2006)

*Re: Would nuclear EMP hurt LEDs?*

Err, if you were that close to a nuclear attack where the EMP would affect you, a light would be the least of your troubles. 

Any circuits attached to the LEDs would be dead, so forget regulation or boost circuits... If anything direct-drive LED would be the most reliable given an EMP. I wonder if filaments in incandescent lamps would catch the EMP and fry themselves?


----------



## zespectre (Jan 25, 2006)

*Re: Would nuclear EMP hurt LEDs?*

Not a scientist so I'm just working in theory. I don't think EMP would fry and LED itself (or if it did that would mean you were close enought that you wouldn't care) but probably any control electronics would be gone.


----------



## The_LED_Museum (Jan 25, 2006)

*Re: Would nuclear EMP hurt LEDs?*

If the flashlight is in an all-metal body, and the LED is not aimed in the direction of the detonation, the unit should not be adversely affected.

I am not a nuclear physicist though, so please take this advise with plenty of crystalline sodium chloride (grains of salt).


----------



## Navck (Jan 25, 2006)

*Re: Would nuclear EMP hurt LEDs?*

I don't think they'll make your LEDs go boom, but from what I know, most flashlights and even computers (Don't listen to the "WE'RE ALL GOING TO DIE TO EMPS" stuff on TV) can have some resistance to it. (I remember something like SFs, Indium Smart, and some very high high end lights being EMP resistant enough to survive small-medium ones. Some with a few other things, toasters for sure, even smart ones, will surive a EMP.)


----------



## beezaur (Jan 25, 2006)

*Re: Would nuclear EMP hurt LEDs?*

The Army has an old book on protecting facilities against EMP. I think the waves are in the mm to cm range. Things encased in substantial conductive enclosures with holes smaller than a few mm are normally considered ok from what I have skimmed in that manual.

See here:

http://cryptome.org/emp.htm

Scott


----------



## Connor (Jan 25, 2006)

*Re: Would nuclear EMP hurt LEDs?*



Genxsis said:


> With all the talk about Iran in the news lately, it seems like a good time to prepare for anything now. With a nuke goes off, it produces electromagnetic pulse (EMP) which is supposed to do alot of damage to electronics. Would that also apply to LED bulbs too since they are a semiconductor rather than a filament bulb?
> 
> Some things are just nice to know. Let's hope we don't find out! But hypothetically, would it destroy an LED?


 
1. Please stop watching so much FOXNews. Then consult your history books to find out the name of the only country that ever used nukes.
2. Yes, an EMP has the potential to destroy a LED, too. No, it won't affect you, because Iran hasn't the necessary carrier to bring a nuclear device to the USA. And if they had one, I have reason to believe they wouldn't detonate the nuke up in the stratosphere (which would cause a major EMP, unlike a bomb going off near the ground).
3. "As Brother Dave Gardner put it, the place to be when a nuclear bomb goes off is wherever you can say, 'What was that?'"
4. If -after the explosion- you are able to say "What was that?" your LED flashlight will probably still work. If not, having a damaged flashlight will be the least of your problems, as "carrot" so eloquently put it. :nana: 

-Connor


----------



## Navck (Jan 25, 2006)

*Re: Would nuclear EMP hurt LEDs?*

http://www.endtimesreport.com/EMP.html
This guy recomends to use a LED flashlight...

http://www.ciaonet.org/olj/sa/sa_oct00ghc01.html
They say


> Light Emitting Diodes (LEDs) LEDs can suffer degradation in optical output by 10 to 20 per cent.



Doesn't look like your LEDs will go *POP* from one so far


----------



## jtr1962 (Jan 25, 2006)

*Re: Would nuclear EMP hurt LEDs?*

Anything in a metal enclosure should be relatively immune from EMP, including metal LED flashlights. The only caveat is that the device must not be plugged into the grid when the EMP hits since the surges through the conductors will probably damage it. Not a problem for flashlights, but by all means unplug the PC and any other appliances you care about.

All that being said, unless it's an air burst of a very high yield weapon, if you're close enough for EMP to damage unshielded devices chances are good that would be the least of your problems. A typical scenario has terrorists detonating a suitcase nuke of a few kilotons yield in a place like Manhattan. The effective EMP range of such a device is less than the effective damage range if I remember correctly. It's only when you air burst weapons with yields in the hundreds of kilotons or megaton range that the effective EMP radius exceeds the blast radius. Only a few countries have such weapons and the capability to air burst them. Again, in such a WWIII scenario, whether or not your LED flashlight worked would be the least of your worries. BTW, EMP will destroy incandescents as easily as LEDs since it basically sends a surge of current through.

I remember that most scenarios of thermonuclear war between the US and USSR involved an initial burst of a multimegaton weapon at a few hundred miles up in the dead center of both countries. This was of course to knock out via EMP as much of the communications and power infrastructure as possible before the first wave of ICBMs.


----------



## BackBlast (Jan 25, 2006)

*Re: Would nuclear EMP hurt LEDs?*



Connor said:


> 1. Please stop watching so much FOXNews. Then consult your history books to find out the name of the only country that ever used nukes.



I'm guessing this is a dig. Lots of countries have used nukes, we currently only have one, on the record, that has denotated them offensively in wartime. Which does not, in the slightest, preclude others from using them in an offensive manner in the future.

Now, what this has to do with the original question, I have no clue. Other than perhaps to impune the motive for the question.



> 2. Yes, an EMP has the potential to destroy a LED, too. No, it won't affect you, because Iran hasn't the necessary carrier to bring a nuclear device to the USA. And if they had one, I have reason to believe they wouldn't detonate the nuke up in the stratosphere (which would cause a major EMP, unlike a bomb going off near the ground).



Iran is not the only country in the world that might want to point a missle at the US. There are others, with missles, and the ability to place them where ever they choose, with a motive to point them at us. I'd say it's a valid concern as any, though I doubt it would be done at the hands of Iran - so I agree there.



> 4. If -after the explosion- you are able to say "What was that?" your LED flashlight will probably still work. If not, having a damaged flashlight will be the least of your problems, as "carrot" so eloquently put it. :nana:
> 
> -Connor



That depends completely on your forsight into the matter, if he continues asking these questions he might be in a very reasonable situation and having an LED light can be very useful.

Anyway, to give you my best understanding on the matter. It comes down to this, the EMP will generate a field which creates current in wires. Shorter wires will generate less current, flashlights are generally small and tolerate reasonable currents depending on the model and design. It's not connected to the grid, or any antennas or cords. The aluminium body, if not used as part of the circuit, would help protect the light. Otherwise I would consider it the weak link. I'd say chances for an aluminium body flashlight that doesn't use the body to conduct are good. Otherwise, it will depend on how strong the field is created by the EMP and how much current in the body results and how tolerant the next component in the circuit is to that current.


----------



## beezaur (Jan 25, 2006)

*Re: Would nuclear EMP hurt LEDs?*



Connor said:


> 1. Please stop watching so much FOXNews. Then consult your history books to find out the name of the only country that ever used nukes.
> 2. Yes, an EMP has the potential to destroy a LED, too. No, it won't affect you, because Iran hasn't the necessary carrier to bring a nuclear device to the USA. . . .
> 
> -Connor



My money says the next nuke popped in anger will be from one of the smaller nations like Iran or Pakistan. China has made saber-rattling threats about retaliatory destruction of Los Angeles. One can only assume that was a reference to nuclear weapons. There is North Korea too.

After World War II there was lots of defensive study done related to bombs -- not reentry vehicles, but bombs -- being smuggeld close to a target using aircraft, trucks, and ships. That was back in the days when B-52s carried just a couple of weapons because of their size. Some nuclear devices are "backpackable" these days. I would argue that Iran has the means to deliver a weapon.

And I don't see what World War II ugliness has to do with anything, Connor from Germany.

Scott


----------



## Sub_Umbra (Jan 25, 2006)

*Re: Would nuclear EMP hurt LEDs?*

This topic comes up every few months. IMO it boils down to two factors: *antenna length* and *shielding.*

I'm with The_LED_Museum on this one. 

Antenna length would seem to present the most significant factor in regard to flashlights. LEDs in flashlights make very short antennas indeed, as they are not electrically coupled to much -- particularly to anything with much length. The length of the antenna will determine the distructive power of the EMP -- that and *proximity.*

When we read about *"...EMP knocking out everything electronic..."* we must remember that the news hustlers are, for the most part, referring to anything electronic that *is attached to the power grid* and _statistically_ they are right -- any LED in anything plugged into the power grid will be toast. The _antenna length_ of any LED in any device plugged into the power grid will be *millions and millions* of times longer than the _antenna length_ of the LEDs in any of your flashlights. That's most of what you need to consider to get into the ballpark of an answer to the OP's question. Once we get to the understanding that in flashlights we are looking at antenna lengths generally less than *one foot* an entirely different picture emerges -- a picture in which the proximity part of the equation becomes _our friend_. (Inverse square law)

While there will probably be no real consensus on the answer to your question, if you're really twitched out about the EMP threat to your lights, you could always take a few and wrap them in three or four layers of tinfoil and stash them away in your kit. I haven't done this with any lights -- but I do have a few shortwave radios put up this way. 


> 2. Yes, an EMP has the potential to destroy a LED, too. No, it won't affect you, because Iran hasn't the necessary carrier to bring a nuclear device to the USA...


Not so. Iran has *successfully* tested the launch of SCUD missiles from surface ships. Because of it's poor accuracy the SCUD is normally considered a _terror weapon_ but there is no doubt that it has more than enough poop to boost a crude (heavy) nuke _high enough_ for an EMP attack. In that mode it has *more than enough accuracy.* 

Bearing that in mind it is easier to see why the powers that be are probably reluctant to allow Iran to develop nukes *and* the Sahab-b missile, which _would appear to only threaten Europe._


----------



## Learjet (Jan 25, 2006)

*Re: Would nuclear EMP hurt LEDs?*

I copped a pulse of EMP from a near lightning bolt once. It blew up the modem and made the colours of my monitor all funny requiring a degauss. It was even switched off at the time. The LED on the front panel still works though.


----------



## Connor (Jan 25, 2006)

*Re: Would nuclear EMP hurt LEDs?*

Heya *@*,


http://en.wikipedia.org/wiki/Nuclear_explosion#Electromagnetic_pulse
So, for realistic flashlight-related nuclear explosion matters, it seems an EMP is kind of an non-issue. It has the potential to destroy electronics, alas a nuke used by an enemy of the USA would probably not be detonated in the stratosphere but on the ground or at a very low altitude for maximum physical damage. The pulse generated by this is rather short-range and probably not of any concern for someone who survives the blast/heat-wave/radiation. 

Everything else would be an end-of-the-world scenario. I guess finding the energy needed to power a flashlight in such a scenario would be the biggest problem, regardless of the light source.

-Connor

[offtopic]
@beezaur
My bet is the next nuke is dropped by either the USA/Israel/UK/France as retaliation for a severe terrorist act of some kind. Regarding rucksack nukes, those are _very_ high tech plutonium nukes. The sophisticated technology necessary to make those is only available to very few countries, excluding Iran. 
My personal opinion on Iran and nukes is: They already have them (or will have in a few months) - and they will never use them, or hand them over to terrorists. It's trivial to determine where a nuke was build by analysis of the remaining radioactive material and everyone knows what will happen right after the identification of the country that build it. The only countries that could probably "get away" with a limited first-strike use of nuclear weapons are the ones with hundreds/thousands of them AND the capability to bring them to any target site quickly, e.g. by ICBMs, submarines and the like.


----------



## Lmtfi (Jan 25, 2006)

*Re: Would nuclear EMP hurt LEDs?*

Your average nuke does NOT generate appreciable EMP. A high altitude event can, however the country you mention is not know for their ability to deliver a weapon to that altitude. I will also point out that if a country has a few nukes - there is no attractiveness in using it at an altitude where the only effect is HEMP (no blast, radiation etc).

EMP affects electronic devices less than common opinion indicates. There is open literature from government labs from the 1980's and 90's to bear that out (available on the web). People have come to believe in EMP effects based upon rumor and movies. Yes, come devices are more succeptable than others, but you would be quite surpised how impervious common commercial products are to full field effect EMP.

Field-expedient EMP-proofing solution like wrapping objects in aluminum foil are interesting but provide extremely little protection - if any.

Trust me on this.


----------



## VidPro (Jan 25, 2006)

*Re: Would nuclear EMP hurt LEDs?*

"chances are good that would be the least of your problems."
i think that would be the most likly scenario, your light working being the least of your problems.

like everybody said, and me guessing, the electro magnetic pulse would have to induct into something. like Inductors. so the lights with inductors and no ferrous shielding seem to be the ones that might stop working.
and anything that blows out when a simple static shock hits it, components that blow out ALREADY anytime anything goes a little bit off.
the GRID, is the perfect huge transformer, the grid going down seems most likly, even with its massive protections they have.

if all else fails, you can just grab a light from sombody whos skin has all fallen off, and use thiers


----------



## BackBlast (Jan 25, 2006)

*Re: Would nuclear EMP hurt LEDs?*



jtr1962 said:


> I remember that most scenarios of thermonuclear war between the US and USSR involved an initial burst of a multimegaton weapon at a few hundred miles up in the dead center of both countries. This was of course to knock out via EMP as much of the communications and power infrastructure as possible before the first wave of ICBMs.



An opening first strike move would look something like this. Nuclear sub SLBM and land based ICBM launch simultaneously. The SLBMs will blanket the opponent with EMP, sub warheads are smallish so they'll probably have two to five to do this. The aim is military communications really, not small civilian electronics or even the infrustructure (though the major infrustructure is a side benifit). There will be maybe a couple minutes of warning before EMP if the country is watching closely. The average person will be able to see the EMP bursts and know that he/she has 10-15 minutes before the ICBMs will hit. This is time enough to act if you have contingency plans.

The main EMP weapons are going to be speed based, and probably less than 1Mt each, I believe ~500kt or less. Even modern land based warheads are not that big anymore, it's all about placement today.


----------



## BackBlast (Jan 25, 2006)

*Re: Would nuclear EMP hurt LEDs?*



VidPro said:


> "chances are good that would be the least of your problems."
> i think that would be the most likly scenario, your light working being the least of your problems.



But if the grid is gone, light is certainly one thing you'll want, no?


----------



## BackBlast (Jan 25, 2006)

*Re: Would nuclear EMP hurt LEDs?*



Lmtfi said:


> EMP affects electronic devices less than common opinion indicates. There is open literature from government labs from the 1980's and 90's to bear that out (available on the web). People have come to believe in EMP effects based upon rumor and movies. Yes, come devices are more succeptable than others, but you would be quite surpised how impervious common commercial products are to full field effect EMP.
> 
> Field-expedient EMP-proofing solution like wrapping objects in aluminum foil are interesting but provide extremely little protection - if any.



Would you happen to have any pointers as to where I might find this open literature? I'm not sure where to start looking.


----------



## VidPro (Jan 25, 2006)

*Re: Would nuclear EMP hurt LEDs?*



BackBlast said:


> But if the grid is gone, light is certainly one thing you'll want, no?



mabey a ground based shelter is what you would want, and then your lights down there are safe from it.


----------



## Connor (Jan 25, 2006)

*Re: Would nuclear EMP hurt LEDs?*



VidPro said:


> mabey a ground based shelter is what you would want, and then your lights down there are safe from it.


 
Ok, end-of-the-world scenario, you survive in a shelter and have enough food and water and you are lucky with the fallouts. Your flashlights survive, too :laughing: .

How do you *charge* your rechargable batteries? Electrical energy will probably be more or less non-existant. Nuclear winter will make using solar energy a problem too, I guess? Realistic, small-scale solutions, please .. "have a generator and a 30.000 liter tank" is not really an option.

-Connor


----------



## Cornkid (Jan 25, 2006)

*Re: Would nuclear EMP hurt LEDs?*

HEY GUYS GOOD NEWS!

My pops (in the army) got me a factsheet on the Surefire Hellfire systems. IT IS EMI shielded!!!

I will upload it asap!  

-tom


----------



## BrightIdeaOSU (Jan 25, 2006)

*Re: Would nuclear EMP hurt LEDs?*

As far as electromagnetic weapons go, the nuclear EMP effect is to modern EM weaponry as a flintlock is to an FN2000. I would be more interested in hearing about the effects on an LED of a microwave or millimeter wave cannon, like those we're testing over in Iraq (coming soon to a protest near you), or perhaps even ground based weapons like the woodpecker grid (Russia) or HAARP (USA) that can pluck the ionosphere like a guitar string. It is not inconcievable, given that these weapons are essentially 30 year old technology only now coming out of the black, that a nation such as Iran or N.Korea could develop weapons along the same lines, and if this were to happen the secrecy of our governments about these technologies could bite back. After all, it's harder to justify dropping the bomb in retaliation for the use of a "nonexistent" weapon than something easy to explain like a nuke, and tracing the origin of ionospheric attacks could be very tricky. 

Just my two cents. BTW, a copper farraday cage with a very fine mesh would be much better than aluminum foil for foiling :laughing: an EMP pulse, irregardless of the source. 

Boy, I bet I'm on the NSA list now!


----------



## nightshade (Jan 25, 2006)

*Re: Would nuclear EMP hurt LEDs?*

The facts are -no one knows for sure. The variables are endless. In the military we trained heavily for N.B.C. events. The loss of your life, quickly, was at times presumed preferable to the long term global effects of a major league event between "capable" nations. For professional speculation try : www.nbc-links.com


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## Lmtfi (Jan 25, 2006)

*Re: Would nuclear EMP hurt LEDs?*



BackBlast said:


> Would you happen to have any pointers as to where I might find this open literature? I'm not sure where to start looking.



I took a quick (1 minute) look and didn't see the paper. The DoD did testing of standard consumer appliances and electronics about 15 or so years ago. There was a paper summarizing their observations on the Web. Essentially it said that they were surprised how many products survived nominal exposure to the field.

Several people have posted that the succeptability is driver primarily by attachment to the power grid or an antenna. While these are efficient coupling methods and could induce a very damaging voltage to the device, free field coupling is just as bad.

I have seen specific consumer equipment exposed to nominal fields over and over and over again - with no ill effect. I'm not saying your LED light would survive (I don't know....I haven't tested one). I will say that worrying about your flashlight (and in my opinion - EMP) is about the last thing you need to be worrying about.


----------



## BackBlast (Jan 25, 2006)

*Re: Would nuclear EMP hurt LEDs?*



Connor said:


> Ok, end-of-the-world scenario, you survive in a shelter and have enough food and water and you are lucky with the fallouts. Your flashlights survive, too :laughing: .
> 
> How do you *charge* your rechargable batteries? Electrical energy will probably be more or less non-existant. Nuclear winter will make using solar energy a problem too, I guess? Realistic, small-scale solutions, please .. "have a generator and a 30.000 liter tank" is not really an option.
> 
> -Connor



Fall-out is 2 weeks, and you can come out. Unless you live downwind/near by a serious groundburst, then it can last over a month. Any hardened targets near where you live?

Nuclear winter is fiction. Volcano? sure! nuclear bombs? no way.

Small scale power solution, solid state electric generator from heat. Small, portable, any heat source works.


----------



## beezaur (Jan 26, 2006)

*Re: Would nuclear EMP hurt LEDs?*



Connor said:


> @beezaur
> My bet is the next nuke is dropped by either the USA/Israel/UK/France as retaliation for a severe terrorist act of some kind. . . .



True. That is another high-probability scenario, and one which has been alluded to by the powers that be. But . . . France???  Still, my money is on local instability in the middle East or South Asia. As for powerful nations getting away with it, that has been the way of warfare since the dawn of warfare, right or wrong.

Anyway, if backpack nukes won't wreck a flashlight very well, then how about the so-called E-bombs that send a directed pulse over a limited area? Those were feared as possible terrorist weapons a while back in the popular press. It isn't a nuke, but still it is a weapon.

Scott


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## JPasquini (Jan 26, 2006)

*Re: Would nuclear EMP hurt LEDs?*



Connor said:


> My personal opinion on Iran and nukes is: They already have them (or will have in a few months) - and they will never use them, or hand them over to terrorists. It's trivial to determine where a nuke was build by analysis of the remaining radioactive material and everyone knows what will happen right after the identification of the country that build it.



Listening to the increasingly inflamatory rhetoric coming out of Iran lately from the mullahs, it seems that they actually _want_ that to happen... It's difficult - and risky - to say what a leader who publicly states that he believes his very reason for being is to hasten the return of the 12th Iman/Madhi via the "apocolypse" will do. I think, IMHO, that's the reason why Chirac last week commented that France would likely retaliate against an attack (of any kind) with a nuclear response. That statement was for the listening enjoyment of one specific nation in the ME.


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## firefly99 (Jan 26, 2006)

*Re: Would nuclear EMP hurt LEDs?*

a) in the air nuclear detonation
the blast / heat-wave / radiation would very likely damaged your equipments or killed you via burnt / melt / fried / steamed.
b) underground nuclear detonation
the blast / heat-wave / radiation would be contain by the soil. 

Either detonation method above, if you have survives the blast / heat-wave.
Then you have a chance to worry about the EMP damaging your equipments.

Any electronic equipments that are switched ON, would be damaged by the EMP. Irregardless of whether the equipments are portable units or plug into the electrical grid. Only those equipments that are switch OFF and unplug from the grid, would survives the EMP.

Only chance of surviving the blast / heat-wave, would be to hide in an underground bank vault. Since nuclear radiation does not cause instant death, you should be able to survives a few years. Unless you have protective gear that shield you from the harmful effects of radiation.


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## Sub_Umbra (Jan 26, 2006)

*Re: Would nuclear EMP hurt LEDs?*



Connor said:


> Ok, end-of-the-world scenario, you survive in a shelter and have enough food and water and you are lucky with the fallouts. Your flashlights survive, too :laughing: .


Are you sure you've covered it all?


Connor said:


> How do you *charge* your rechargable batteries? Electrical energy will probably be more or less non-existant. Nuclear winter will make using solar energy a problem too, I guess? Realistic, small-scale solutions, please .. "have a generator and a 30.000 liter tank" is not really an option.
> 
> -Connor


Generally people who can't think positively about their prospects of survival won't survive. There is a certain Darwinian justice to it. Anyone who can get past their own helplessness may move in the general direction of preparedness. While the future is always somewhat uncertain, one thing does seem highly probable -- when the power goes out _you_ won't be charging any cells.


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## jtr1962 (Jan 26, 2006)

*Re: Would nuclear EMP hurt LEDs?*



Sub_Umbra said:


> Generally people who can't think positively about their prospects of survival won't survive. There is a certain Darwinian justice to it. Anyone who can get past their own helplessness may move in the general direction of preparedness.


It's one thing to be prepared and survive a natural disaster of some sort like Katrina, or perhaps a one-time terrorist nuclear attack. At least eventually you know your life will return to normal. Honestly, I'm not sure I'd want to survive a global thermonuclear war. Even if you survive, what is there to really look forward to the rest of your life? You'll basically be back in the Middle Ages watching the rest of your species die a long, slow agonizing death from famine, disease, exposure, radiation poisoning, cancer, etc. There will be zero prospect of even a semblance of the life you once knew returning. And in the power vacuum which would suddenly ensue, you'll have all sorts of loonies proclaiming themselves the new leaders, and trying to take control of what little life you have left. No thanks, I'd rather be vaporized in the first wave of ICBMs. Let's all hope mankind is never crazy enough to embark on this course. Every book I ever read on the subject has a common theme-there are no winners in global thermonuclear war, just the dead or the dying.


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## Sub_Umbra (Jan 26, 2006)

*Re: Would nuclear EMP hurt LEDs?*



jtr1962 said:


> ...Honestly, I'm not sure I'd want to survive a global thermonuclear war...


I'm not sure either, *but I will not decide today.* I can decide I don't want to go on later -- that's easy. If wondering about whether or not someone would _want to survive_ stops them from ever preparing for things bit by bit *then they've already decided for themselves by inaction.* 

I can understand people asking themselves that type of question but I'll never get why so many ask questions like that and then never make any preparations at all. The doubt is legitimate. To go from the doubt to assuring by inaction that I would have no options is the part that I don't get. I would rather prepare as I can for whatever I can so I may have as many options open to me as possible if something terrible happens. I'm sure not going to let today's doubts about one possible future scenario stop me from getting ready.

What if you got into that scenario and then decided that yes, you definately did want to survive? I would hope that that idea that you may want to survive would have crossed your mind at some time before that point.

Right now I've got to get the cat back into the lava tube... 

This is sounding more and more like Cafe material.


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## joema (Jan 26, 2006)

*Re: Would nuclear EMP hurt LEDs?*

Nuclear EMP (esp from high altitude) can affect electronics far beyond the zone of immediate blast and radiation. In fact a single high altitude detonation over the central US could affect the entire country.

Most susceptible are long conductors which can act as antennas. But even electronics not connected to long conductors can have very large currents and voltages induced. The EMP field under some conditions can cause hundreds of amps at hundreds of volts within electronics.

The exact result is complicated since there are many variables: surface, air or high altitude detonation, distance, conductor (antenna) length, degree of shielding, susceptibility of the electronics to damage, and type of EMP waveform (there are several).

For detailed information, see 
http://www.fas.org/nuke/intro/nuke/emp.htm
http://www.fas.org/nuke/intro/nuke/emp/toc.htm


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## Lmtfi (Jan 26, 2006)

*Re: Would nuclear EMP hurt LEDs?*

Unfortunately - there is more wild speculation, guessing, urban myth and "something I learned at the movies" being peddled as fact in this thread more than any other thread I think I've read on this forum.


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## zespectre (Jan 26, 2006)

*Re: Would nuclear EMP hurt LEDs?*

lmtfi - if you have facts to add or something constructive to say then by all means educate us, post facts, references, etc.


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## BBL (Jan 26, 2006)

*Re: Would nuclear EMP hurt LEDs?*

Soo... who puts his SF L4 into the microwave oven to find out?


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## Connor (Jan 26, 2006)

*Re: Would nuclear EMP hurt LEDs?*



BackBlast said:


> Nuclear winter is fiction. Volcano? sure! nuclear bombs? no way.


 
Could you supply some links to confirm this statement, please?

-Connor

@Sub_Umbra
Nice try, but oh so wrong.


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## Ras_Thavas (Jan 26, 2006)

*Re: Would nuclear EMP hurt LEDs?*

Some interesting information can be found in this .pdf

http://www.globalsecurity.org/wmd/library/policy/army/fm/3-3-1/fm3-3-1.pdf

Appendix C on page 170 deals with EMP.


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## Learjet (Jan 26, 2006)

*Re: Would nuclear EMP hurt LEDs?*

Wear the foil hat and don't forget to duck and cover.


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## raythompson (Jan 26, 2006)

*Would nuclear EMP hurt LEDs?*

Who really cares?

In the situation of large scale nuclear (or as Bush says Nuculer) conflict we won't need flashlights. Most of us will probably glow in the dark.:lolsign: Then size will really matter.


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## Lmtfi (Jan 26, 2006)

*Re: Would nuclear EMP hurt LEDs?*



zespectre said:


> lmtfi - if you have facts to add or something constructive to say then by all means educate us, post facts, references, etc.



I have posted positions on most of the relevant areas discussed so far. Unfortunately, discussions of this subject usually drift towards assumption - which is probably to be expected bacause few people have any real experience related to the topic. There is often considerable (understandable) apprehension related to this subject and people citing summaries of newpaper articles - many dating back to the 1940s - and many of those "facts" are little more that oft-repeated urban myth.

The first place where incorrect assumption drifts in is that all nuclear explosions create an EMP effect likely to damage electronics over a broadly distributed area. This is incorrect. Although I am not an authority on the vast array of international launch platforms, it is not my understanding that many countries posess both the tested sophisticated weapon capability as well as the ability to place it at a sufficient altitude (lets say 200 miles or higher). (Someone said that a SCUD can reach effective HEMP-generating altitudes. I'm not a SCUD authority - but my understanding is that the SCUD cannot. I'm willing to be proven wrong though). 

Explosions close to the ground produce a different type of EMP - known as SREMP. Its EMP propagation can be strong but is significantly limited - roughly within the blast radius (can't remember the psi). In my opinion - if you are within a nuclear blast radius - EMP is the least of your worries. 

There are assumptions that countries with a few nukes (probably the ones people are worried about these days) are limited in their ability to deliver same to or near the continental US, have little or no tested/proven ability to place them at altitude and are (my opinion) *highly* unlikely to waste such a rare device on an EMP-generating experiment. Any country capable of satisfying all of the criteria necessary to create a broad, damaging EMP effect in the US is smart enough to know that delivery of same would certainly result in the total destruction of that country in short order.

The US has protected its critical military (and to some degree critical national infrastructure) from EMP for some years now. Information on this is available in open source on the web. The US has also engaged in considerable testing for quite some time - again, information available on the web. Grounding, bonding and shielding practices to protect against EMP are well-known and documented. Having worked in this area I will tell you that actual implementation of these protections is complex and multi-faceted. Simple solutions are rare and the ability for EMP to damage a device is through several ingress paths. (Miss one and lose the device/system). I will also note that well-engineered and implemented protections are meaningless without testing. Testing can bring surprises. 

As I mentioned before - there is a common assumption that "all electronics will be fried" from a nominal EMP event. This is inconsistent with my experience in actual testing (all instrumented, documented in calibrated nominal fields). We actually forgot that there were unprotected consumer/industrial devices exposed to the field and were surprised that they suffered no ill effect. (In all fairness I will note that we accidentally left an aperture open just before a pulse was generated. We ran like the Three Stooges to close it when we heard the pre-pulse siren - but not in time. We ended up destroying a very (VERY) expensive piece of XYZ. The consumer electronics took and survived many of the same events without protection).

I am by no means underestimating the potential impact of a nuclear device - I just do not believe that EMP is the effect the average citizen needs to be concerned about. IMO - EMP is an extremely unlikely threat and folks shouldn't be concerned with it.


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## zespectre (Jan 26, 2006)

*Re: Would nuclear EMP hurt LEDs?*

Lmtfi - (not gonna quote the whole reply). Thanks, that's some interesting information and tweaks my interest in the subject.


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## Zigzago (Jan 26, 2006)

*Re: Would nuclear EMP hurt LEDs?*



BBL said:


> Soo... who puts his SF L4 into the microwave oven to find out?



In a previous thread on this topic Peter Gransee said he ran an Arc AAA through a microwave and it still worked afterwards.


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## Sub_Umbra (Jan 26, 2006)

*Re: Would nuclear EMP hurt LEDs?*



Lmtfi said:


> ...Although I am not an authority on the vast array of international launch platforms, it is not my understanding that many countries posess both the tested sophisticated weapon capability as well as the ability to place it at a sufficient altitude (lets say 200 miles or higher). (Someone said that a SCUD can reach effective HEMP-generating altitudes. I'm not a SCUD authority - but my understanding is that the SCUD cannot...


There was an oft repeated story in the 1980s that the press used to trot out:
That "...a 200MT blast 200 miles above Kansas City would knock out every phone in the continental US."

I didn't say that. I never mentioned HEMP. I never mentioned a 200 mile altitude.


Sub_Umbra said:


> ...Iran has *successfully* tested the launch of SCUD missiles from surface ships. Because of it's poor accuracy the SCUD is normally considered a _terror weapon_ but there is no doubt that it has more than enough poop to boost a crude (heavy) nuke _high enough_ for an EMP attack. In that mode it has *more than enough accuracy.*


That's what I said and I'll stand by it.

A quick Google search will show that a SCUD-D has a payload of 985 kg (2171 lbs) and an apogee of 200 km (124 miles). That is more than enough payload and altitude to mount a serious EMP attack with a crude weapon.


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## Cornkid (Jan 26, 2006)

*Re: Would nuclear EMP hurt LEDs?*

Sub Umbra... 
200MT LOL... LOL

200 Megatons? That is rediculous!!!!

THe biggest Nuke that I know of is a 50 MEGATON device. Anything over that is mind-boggling!

-tom


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## quarkstar (Jan 26, 2006)

*Re: Would nuclear EMP hurt LEDs?*

IMO I don't think anyone can accurately predict what EMP would do to anything. As I understand it, the EMP (and it's effect) produced would be dependent on type, size, distance, altitude of the detonation, topography, weather, and technologies subjected to the EMP...and a whole host of other imponderables. There are simply to many variables effecting that (hypothetical) question and it's answer. 

For myself, I would not worry to much about it. In the event of an atomic attack the least of my worries will be the status of my flashlight.


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## Spectrum (Jan 26, 2006)

*Re: Would nuclear EMP hurt LEDs?*

Some very interesting articles:

http://www.house.gov/hasc/testimony/106thcongress/99-10-07wood.htm
http://www.doh.wa.gov/ehp/rp/air/factsheets-pdf/FactSht41.pdf
http://www.globalsecurity.org/wmd/library/policy/army/fm/3-3-1_2/Appc.htm
http://www.dhs.gov/dhspublic/interapp/editorial/editorial_0284.xml


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## BackBlast (Jan 26, 2006)

*Re: Would nuclear EMP hurt LEDs?*



Connor said:


> Could you supply some links to confirm this statement, please?
> 
> -Connor



I guess there is no need for you to prove the proported theory of nuclear winter yourself? Burden of proof is totally on me since it's automatically true because you've inherited it from the popular conscience. Fiction was probably a harsh word, but if you read the theory, there are just too many unknown factors to give it validity. It's conjecture at best.


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## joema (Jan 26, 2006)

*Re: Would nuclear EMP hurt LEDs?*



Cornkid said:


> 200 Megatons? That is rediculous!!!!...THe biggest Nuke that I know of is a 50 MEGATON device. Anything over that is mind-boggling!..


There's no upper size limit for fusion bombs. In theory you could make a 50,000 megaton bomb. More info: http://en.wikipedia.org/wiki/Nuclear_weapon_yield

But unless you haul it in a semi trailer, there's a practical limit based on air delivery platforms due to the bomb weight. The maximum theoretical yield/weight efficiency is 6 megatons yield per metric ton mass. The maximum yield ratio thus far achieved is 5.2 megatons per metric ton, so a 200 megaton device would weigh 38.5 metric tons (84,877 lbs). Even the space shuttle couldn't lift that to orbit -- it would require a Saturn V.

Even for an easier intercontinental suborbital trajectory, no current launcher could lift that. It's also far above the max payload capacity of a B-52.

A SCUD-D with a 985kg payload could lift an approx 5 megaton bomb. If it detonated at 200 km there would be significant EMP effects over a broad area -- roughly half the continental US.

However -- it's likely no small power would waste a nuke on EMP. Given a limited arsenal, they are too valuable as a direct weapon to squander on EMP.

Of course a larger power like Russia could (and likely would) use dedicated EMP nukes. The most effective way would NOT be a SLBM launch, but concealing several in low orbital satellites and doing a coordinated surprise detonation as a prelude to a nuclear attack.

Re whether it's possible for a small power to field a high altitude nuclear EMP weapon, the initial post asked about EMP effects, not what country could launch one.

I still don't know how susceptible an LED flashlight is to EMP, but under the right conditions EMP can damage more resilient components than an LED. A high altitude EMP can impose 50,000 volts per meter, so even tiny leads can receive enough EMP to damage electronics.

If you examine this document, it appears even fairly robust components (carbon resistors) can be damaged by significant EMP:

http://www.fas.org/nuke/intro/nuke/emp/c-2fig.pdf

A metal body flashlight might be more resistant to EMP and a plastic body flashlight more susceptible. OTOH, the metal body isn't earth grounded. If it's electrically connected to the internal circuitry in any way, it's possible EMP could damage it.


----------



## Roy (Jan 26, 2006)

*Re: Would nuclear EMP hurt LEDs?*

Since this thread has gotten pretty far away from it's origional subject, I moved it to the "CAFE". Have fun!!



Roy


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## Connor (Jan 26, 2006)

*Re: Would nuclear EMP hurt LEDs?*



BackBlast said:


> I guess there is no need for you to prove the proported theory of nuclear winter yourself? Burden of proof is totally on me since it's automatically true because you've inherited it from the popular conscience. Fiction was probably a harsh word, but if you read the theory, there are just too many unknown factors to give it validity. It's conjecture at best.


 
No problem. Let's start with this:
http://en.wikipedia.org/wiki/Nuclear_winter
http://www.the-spa.com/jon.roland/vri/nwaos.htm

-Connor


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## jtr1962 (Jan 26, 2006)

*Re: Would nuclear EMP hurt LEDs?*



Sub_Umbra said:


> There was an oft repeated story in the 1980s that the press used to trot out:
> That "...a 200MT blast 200 miles above Kansas City would knock out every phone in the continental US."


The largest weapon ever detonated was ~108 MT by the former USSR. The reason they got away from these massive yield weapons was because they were of no use militarily. I heard a lot of the energy ended up going into space where it was useless because of the sheer size of the explosion, and the weapons required a huge booster to send to their target. Nowadays I don't believe we have anything bigger than about 2 MT. The reason for having the huge bombs was mainly to knock out large cities. With MIRV capability you can do the same as effectively with several precisely placed 1 MT or so warheads while using a much smaller missile.



> A quick Google search will show that a SCUD-D has a payload of 985 kg (2171 lbs) and an apogee of 200 km (124 miles). That is more than enough payload and altitude to mount a serious EMP attack with a crude weapon.


Yes, but it is incapable of reaching the continental US, much less the dead center of the US, from Iran or Iraq. Of course, if a SCUD missile can be smuggled into the US they might have a shot at creating an EMP event but that's highly unlikely.


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## joema (Jan 27, 2006)

*Re: Would nuclear EMP hurt LEDs?*



jtr1962 said:


> The largest weapon ever detonated was ~108 MT by the former USSR.


It was actually about 50 megatons. It theoretically could have been modified to reach about 100 megatons. http://en.wikipedia.org/wiki/Tsar_bomba



> I heard a lot of the energy ended up going into space where it was useless because of the sheer size of the explosion


That's not correct. However with any bomb, radiation effects dinimish as the square of the distance, and blast effect diminish as the cube of the distance. IOW if you're 3 miles away from ground zero, the blast is only 1/27th compared to 1 mile away. That explains a key reason why large unitary weapons have limited utility. See inverse square law: http://en.wikipedia.org/wiki/Inverse_square_law



> the weapons required a huge booster to send to their target


If you mean the above Soviet 50 mt bomb, no operational booster was powerful enough to lift it. It could only be air carried (and just barely) by the largest Soviet bomber.



> Nowadays I don't believe we have anything bigger than about 2 MT


For the US, that is correct. However as recently as 2004, some 9 megaton warheads were in the active inventory, apparently dedicated to an earth-penetrating role for destroying deeply buried command posts:

http://www.johnstonsarchive.net/nuclear/multimeg.html#U1



> The reason for having the huge bombs was mainly to knock out large cities.


The reason for huge bombs was mainly for hardened targets, not large cities. Cities are very "soft" in military terms and don't require a huge bomb.

Huge bombs were also used because MIRV technology did not exist at that time, also precise targeting wasn't possible.



> With MIRV capability you can do the same as effectively with several precisely placed 1 MT or so warheads while using a much smaller missile.


Current US MIRV warheads are in the 100-300 kiloton range (475kt for Trident II), not megaton. http://www.geocities.com/minuteman_missile/specs.htm
http://nuclearweaponarchive.org/Usa/Weapons/Allbombs.html


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## Sub_Umbra (Jan 27, 2006)

*Re: Would nuclear EMP hurt LEDs?*



Sub_Umbra said:


> A quick Google search will show that a SCUD-D has a payload of 985 kg (2171 lbs) and an apogee of 200 km (124 miles). That is more than enough payload and altitude to mount a serious EMP attack with a crude weapon.





jtr1962 said:


> Yes, but it is incapable of reaching the continental US, much less the dead center of the US, from Iran or Iraq. Of course, if a SCUD missile can be smuggled into the US they might have a shot at creating an EMP event but that's highly unlikely.



Come on, this is only a two page thread! Although I've already *RE*-posted this once _on this page._ I don't want to leave anyone behind. I would have hoped that you would have read the first page -- you did post to it. Anyway, for the third time, here goes:



Connor said:


> 2. Yes, an EMP has the potential to destroy a LED, too. No, it won't affect you, because Iran hasn't the necessary carrier to bring a nuclear device to the USA...
> -Connor





Sub_Umbra said:


> Not so. Iran has *successfully* tested the launch of SCUD missiles from surface ships. Because of it's poor accuracy the SCUD is normally considered a _terror weapon_ but there is no doubt that it has more than enough poop to boost a crude (heavy) nuke _high enough_ for an EMP attack. In that mode it has *more than enough accuracy.*



If you don't beleive that, fine, just read the rest of the thread before you challenge it. Some of it has already been covered. Also, I never asserted that a serious attack had to be mounted 1) from Iran, OR 2) delivered to " the dead center of of the US", OR 3) that it was even possible to launch such an attack from Iran, as you inferred.

If Iran were to execute a successful EMP attack using only 1/5 of the payload capacity of a SCUD-D on the east coast of the US the damage would be unfathomable -- in terms of *both* our ecomomy and our lifestyle, no matter where in the States you live.


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## jtr1962 (Jan 27, 2006)

*Re: Would nuclear EMP hurt LEDs?*



Sub_Umbra said:


> If Iran were to execute a successful EMP attack using only 1/5 of the payload capacity of a SCUD-D on the east coast of the US the damage would be unfathomable -- in terms of *both* our ecomomy and our lifestyle, no matter where in the States you live.


Fine, I agree an EMP attack is theoretically possible using existing SCUD missiles if:

1) Iran has a nuclear weapon.
2) The ship can get close enough to the US so that the SCUD missile can carry the warhead near enough to the US to cause an EMP event on the East Coast.
3) The missile isn't blown out of the sky by a Patriot or other type of ABM.

Now as to actual probabilities, I'd say eventually 1) has 100% chance of happening if it hasn't already happened. 2) is highly unlikely but certainly possible if someone in charge of coastal defense is asleep at the wheel. 3) is somewhat unlikely but let's say the missile has a 25% of getting through. The main problem as I see it then is Iran getting a ship close enough to the US to execute the attack. Remember that chances are if they don't do it on the first try coastal surveillance will be stepped up to the point that it will be virtually impossible the second time.

I'll also add a good reason why this attack isn't likely even if all three conditions were 100% possible. Of course, I'm going on the operating assumption that whomever is in charge of Iran is sane. Anyway, what happens if Iran successfully carries out such an attack? Sure, the Eastern seaboard is paralyzed and rebuilding the information/power infrastructure will take years. However, nothing will prevent the US from wiping Iran right off the map, and there will certainly be widespread public support for doing exactly that at least in the US, especially in those areas hit by the attack. My guess is if this happens Iran gets a few tens of megatons dumped on them. Indeed, I've long felt that 9/11 merited such a response had it been orchestrated by a nation instead of a rogue group of terrorists. A nuclear attack on the US, whether EMP or suitcase nuke, would merit a nuclear response. No sane leader would dare attack the US, much less one which could offer scant response to a US nuclear attack. The US would certainly hesitate to respond with nukes to a nuclear attack if the culprit were Russia or China since they could expect massive nuclear retaliation in return. However, in the scenario mentioned Iran would have already shot its proverbial load, and the US could wipe it off the map with impunity. Not a pretty scenario, but in that circumstance as President I wouldn't hesitate for a moment to push the button. It would make any other nation contemplating such an attack think long and hard about the consequences. Now of course, I said earlier my operative assumption was that the leader(s) of Iran were sane. Given some of the rhetoric I hear coming from their leaders, this may not be a valid assumption.

P.S. I personally feel the US will be attacked on her own soil with WMD sometime in the not too distant future, but it will most likely be Al Quada or some other terrorist organization, not a sovereign nation like Iran.


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## Sub_Umbra (Jan 27, 2006)

*Re: Would nuclear EMP hurt LEDs?*



jtr1962 said:


> Fine, I agree an EMP attack is theoretically possible using existing SCUD missiles...



Err, that's what I said two days ago...oh well, better late than never.


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## BackBlast (Feb 2, 2006)

*Re: Would nuclear EMP hurt LEDs?*



Connor said:


> No problem. Let's start with this:
> http://en.wikipedia.org/wiki/Nuclear_winter
> http://www.the-spa.com/jon.roland/vri/nwaos.htm
> 
> -Connor



Yes... wikipedia, where everyone and their dog may offer up their own opinions. I don't consider that a good place for an original source, it's only good for background information, and even then...

As for the other site... Is it warming or cooling? Nuclear summer? Make up their minds? They all cite the same studies which I find dubious (the studies). They also found a way to link in warming, CO2, all that jazz. I think we're going to have to agree to disagree. My position is it is only conjecture on numbers thrown into the air and run through (likely flawed) models. People may tout them all they like but it doesn't make it any more than that. There's enough myth about nukes as is.


----------



## BackBlast (Feb 2, 2006)

*Re: Would nuclear EMP hurt LEDs?*



jtr1962 said:


> 3) The missile isn't blown out of the sky by a Patriot or other type of ABM.



It is my understanding that the Patriot system is not designed for the boost phase. I'm unaware if we currently have such a functional system. I would be pleasently surprised to learn of the existance of such a system and wonder why it hasn't been deployed to date.


----------



## C4LED (Feb 2, 2006)

*Re: Would nuclear EMP hurt LEDs?*



BackBlast said:


> It is my understanding that the Patriot system is not designed for the boost phase. I'm unaware if we currently have such a functional system. I would be pleasently surprised to learn of the existance of such a system and wonder why it hasn't been deployed to date.



About this subject (in general) - Have a look at this:

"Putin unveils 'new super missile'

President Putin revealed details of a new Russian missile
Russia has developed missiles capable of penetrating any missile defence system, President Vladimir Putin says." 

http://news.bbc.co.uk/2/hi/europe/4667532.stm


----------



## Sub_Umbra (Feb 3, 2006)

*Re: Would nuclear EMP hurt LEDs?*

I read the articles about the 'new super missile' also. While it may be somewhat alarming there is more to the story than meets the eye. It is in the interest of those who fight for our news dollars to make each story as sensational, creepy and scary as possible. Good news is no news. It is also in Putin's best interest to gin up the story as much as possible.

The article skips over a few important points. In order to do what they say the new missile does it will require at least one more rocket motor (perhaps four more) in places where none were needed before. Every pound of new motor will directly translate into one pound less payload. (The warhead(s) are the payload.) The additional motor(s) will also require their own fuel which will also diminish the payload proportionatly. That is one reason why this hasn't been done before.

The negatives inherent in this design do not stop there. Additions of extra rocket motors and fuel also add greatly to the overall complexity of these devices, making them more prone to failure. Anyone who followed the Russian Naval war games not long ago will recall Putin's embarassment at being on a ship in the area of the games and having first one and then a day or so later another missile fail to launch entirely. IIRC no missiles were successfully launched in spite of the fact that it was a huge PR event and Mr. Big was there himself. Bear in mind that those missiles were not the new super missiles. They were older, mechanically less complex missiles that the crews had much more familiarity with and still they couldn't be made to launch, even with the boss hanging around.

When added to the Russian's history of bragging about items in their military arsonal that do not exist these stories raise many more questions than they answer. (search for "missile gap" and "bomber gap" for details)

This new design would also seem to creat new SDI options for the States where none existed before. One of the reasons SDI currently places so much importance on targeting during 'boost phase' is because the IR signature is much easier to detect during launch and boost than during the rest of the ballistic path where the body of the missile blends into it's backround and becomes hard to target. If they have a missile that reveals it's position and trajectory during a portion of it's flight in which their previous missiles were essentially invisible they will present new options to defenders. The final course correction will present an IR signature where none existed before. Of course, the Russians could add more countermeasures -- but only at the expense of losing more pounds of payload and adding to what already seems to be an unmanageable level of complexity. Nothing is free.

I'm not saying that the new missiles should be dismissed as a threat -- only that all we have heard about them has come from biased parties (Putin and The Media) and they both will only tell the parts of the story that serve themselves.

About the Patriot missiles: They were never *designed* for any of the missions that they are now deployed for. IMO the most interesting thing about the Patriots is their software. Constant software upgrades have made them what they are today. Way back when the first Patriots were designed they had a totally different mission. They were originally created only to shoot down intruding manned jet fighters. That is shockingly different than their current mission and the evolution is the result of advances in their software. Mr Putin should review the software upgrades of the Patriot and the resulting mission shifts that have accompanied them. Even at the end of the 20th century it has been shown that software upgrades may radically transform existing weapon systems. 

I'm not asserting that a software upgrade of the Patriot Missile System will render the new Russian 'super missile' useless. I'm only saying that new software *has completely transformed* the performance and mission of the Patriot. It should be noted that the States employ a great many systems that may be changed radically with a just a software upgrade.

For the above reasons Putin should be very careful about what he says about his new missile and how he deploys them. As in the case of the 'bomber gap' and then the 'missile gap' this story may spur the States to develop a more advanced technology in one or more areas that render the fantastic claims about this new weapon moot.

I suspect that Putin's statements about this new weapon were not actually aimed at audiences in the States. IMO that wouldn't make any sense. It seems far more probable that Putin released this PR to have an impact on someone who is already in Russia's sphere of influence -- or some country(s) that Putin hopes to soon bring into Russia's sphere of influence. While outwardly this story appears to be aimed at Western countries, it actually may be very much contrived for *strictly regional impact.*


----------



## BackBlast (Feb 3, 2006)

*Re: Would nuclear EMP hurt LEDs?*

Yes, I've been keeping up on these announcements. I do not like the developments for a number of reasons.

1) The missle in question appears to be a re-re-re annoucement of the SS-27 road mobile ICBM (up to 6 warheads, capable of various counter measures to ABM systems, etc). I've seen it a number of times.
2) The only point of this development is an intented nuclear attack on the United States. There is no other logical purpose for the missile.
3) The cold war isn't in full swing anymore in the West, but Russia and China are arming like mad. These announcements seem to be to influence parts of the world to their side perhaps, they never seem to make it to the US press. Or if it does, it's not pounded on the front page like snide comments from Iran or other such special animals. I can't imagine it's a fun prospect for a country to pick the losing side of a world war.


----------



## Sub_Umbra (Feb 3, 2006)

*Re: Would nuclear EMP hurt LEDs?*



> ...2) *The only point of this development* is an intented nuclear attack on the United States. There is no other logical purpose for the missile.


Emphasis mine.

Are you sure? I'm not. War may be waged in many ways. It is far more likely that Putin is trying to influence, bully, cajole or coerce someone much closer to Russia than to actually have an impact on the States by making noises that they threaten the US. The more Russia *appears* to threaten the only Superpower the more leverage they have for twisting the arms of their smaller neighbors and regional trading partners. I won't be sleeping in the bunker tonight.  

They only threaten the US in the same old way that they have for thirty years -- if one of their leaders is nuts enough to attack the States he will only have the satisfaction of having done some damage for a half an hour before he is vaporized.

As I said, Russia can't even reliably launch weapons they've trained with and had deployed for *years and years.* Weapons that they are familiar with. Weapons that are much less complex than the new 'Super Missile'. 

If they _wanted_ to attack the US and had _the means_ to attack the US, _why not just do it?_ Suprise _is_ a strategic element. If that's what they want than what's all the talk about? Some heretofore unknown sense of fairness? Do they warn us so that we may prepare and give them a better fight? I think not. This would be totally out of charactor with their military exploits of the last 100 years. 

They have someone else in the crosshairs with this gambit. Some 'weak sister' that they want to shore up. Look at the political and trade aspirations of Russia's neighbors for the real answer. In other words, among Russia's neighbors who are balking at Russia's trading demands (including but not limited to oil and future pipeline routes), who might Putin feel may be swayed towards Russia's position if they felt that the balance of world power were shifting towards Moscow?

Most of the time *talking* about missiles is far more productive than actually firing them.


----------



## BackBlast (Feb 4, 2006)

*Re: Would nuclear EMP hurt LEDs?*



Sub_Umbra said:


> Are you sure? I'm not. War may be waged in many ways. It is far more likely that Putin is trying to influence, bully, cajole or coerce someone much closer to Russia than to actually have an impact on the States by making noises that they threaten the US. The more Russia *appears* to threaten the only Superpower the more leverage they have for twisting the arms of their smaller neighbors and regional trading partners. I won't be sleeping in the bunker tonight.



There are cheaper ways of doing this. We are talking about the most advanced ICBM in the world. It is considered quite operational and estimates are they are deploying them at the rate of about 3 a month.



> They only threaten the US in the same old way that they have for thirty years -- if one of their leaders is nuts enough to attack the States he will only have the satisfaction of having done some damage for a half an hour before he is vaporized.



I am not so overly confident in our military's capacity or dubious of Russia's.
1) We have dismantled our best missile system.
2) The best we have in the field currently is a missle deployed in the 70s, and they are _aging_, which effects the outcome of the bombs. I think they still work pretty good. None the less it's an anchient system by today's standards and possibly could be defeated by Russia's AMB systems.
3) The US has no public preparations compared to Russian nuclear war preps. Just look at such projects as Yamantau Mountain. Do a little research, it's scary stuff. ("The only potential use for this site is post-nuclear war..." --- Rep. Roscoe Bartlett;  "Yamantau Mountain is the largest nuclear-secure project in the world... They have very large train tracks running in and out of it, with enormous rooms carved inside the mountain. It has been built to resist a half dozen direct nuclear hits, one after the other in a direct hole. It's very disquieting that the Russians are doing this when they don't have $200 million to build the service module on the international space station and can't pay housing for their own military people," ---Rep. Bartlett. )



> As I said, Russia can't even reliably launch weapons they've trained with and had deployed for *years and years.* Weapons that they are familiar with. Weapons that are much less complex than the new 'Super Missile'.



I'm not sure where you get this information. Certainly some failures are bound to occur on all sides, and the more QA you have will minimize these. But they certainly are parameterized and I doubt they are as bleak as you paint them. I would certainly not stake the national security of the US on it.



> If they _wanted_ to attack the US and had _the means_ to attack the US, _why not just do it?_ Suprise _is_ a strategic element. If that's what they want than what's all the talk about? Some heretofore unknown sense of fairness? Do they warn us so that we may prepare and give them a better fight? I think not. This would be totally out of charactor with their military exploits of the last 100 years.



Because, for some _stupid_ reason the US is currently disarming, would you not wait and let your enemy do that? Besides that the US media is complicite in not letting too many Americans hear him say things like that too loudly with the implications as to what he is saying. So he gets away with it. It appears that _our leaders_ are complicite in all this as well, strange things afoot and not all is as it appears on the surface.

Edit: added Bartlett quotes.


----------



## Sub_Umbra (Feb 4, 2006)

*Re: Would nuclear EMP hurt LEDs?*

Russia's ABM "system" is prehistoric and only covers Moscow.

The notion that the media is somehow complicit in a coverup is a stretch. Putin has bragged about his new baby in public. It is no secret. More know about it than just you and I, believe me. You still have not made the point that the US is the real target. If the States are the target, why did Mr Big go out of his way to make his new, revolutionary killer weapon known to the whole world? What does he gain by that? He tips off the largest economy in the world that he has something that he may use to cut off their heads. It doesn't make any sense. Did he want us to start working on countermeasures last week? Why would he want that?

His borders are so long and his conventional forces so messed up that last year he announced Russia would respond with nuclear weapons to security scenarios that Russia has always handled with conventional forces. His situation forced his hand. He is playing regional games with this new weapon.

I'm not really into massive, global conspiracy theorys. 

YMMV


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## BackBlast (Feb 4, 2006)

*Re: Would nuclear EMP hurt LEDs?*

Suit yourself, I think I'm done here.


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## C4LED (Feb 4, 2006)

*Re: Would nuclear EMP hurt LEDs?*



BackBlast said:


> 3) The US has no public preparations compared to Russian nuclear war preps.



Yes... there are no "public" preparations...


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## etc (Oct 14, 2006)

It has just occured to me that the Achille's hill of LED lites is that they can be destroyed by the EMP. They are solid state electronics which lack an incandescent bulb of 19th century technology. Is that so or I missing something?


I have lots of lites, * all * LED.


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## Cornkid (Oct 14, 2006)

*Re: Are LEDs vulnerable to EMP?*

I would think that an Electromagnetic pulse with enough power could easily fry the circuitry of most LED lights. The LED itself, Im not sure.
tom


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## Gnufsh (Oct 14, 2006)

*Re: Are LEDs vulnerable to EMP?*

I would imagine an emp could destroy a LED. I guess you could shield it with something...


----------



## TinderBox (UK) (Oct 14, 2006)

*Re: Are LEDs vulnerable to EMP?*

I read that a single layer of tin foil, the stuff you cook your roast in is all you need to protect all your electronic equipment from an EMP blast.

regards.

John.


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## Sable (Oct 14, 2006)

*Re: Are LEDs vulnerable to EMP?*

I'm not sure as an EMP would destroy the die itself, but it could damage anything like a complex circuit board (U2 or FLuPIC, for example). However, since just about the only thing that can create an EMP large enough to worry about is a large-scale nuclear weapon...I think that you might have other things to worry about in any event. 

Cheers!


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## ADDICTED2LITE (Oct 14, 2006)

*Re: Are LEDs vulnerable to EMP?*

If tin foil will protect the light, why not the aluminum case the light is made of?


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## Gnufsh (Oct 14, 2006)

*Re: Are LEDs vulnerable to EMP?*



TinderBox (UK) said:


> I read that a single layer of tin foil, the stuff you cook your roast in is all you need to protect all your electronic equipment from an EMP blast.
> 
> regards.
> 
> John.


Make sure to ground it to something though (maybe the body of your flashlight would work?). I would actually suggest copper mesh (and you could still get light through that).


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## IsaacHayes (Oct 14, 2006)

*Re: Are LEDs vulnerable to EMP?*

incandencent lights can burn out too from EMP! Don't forget about that.


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## Biker Bear (Oct 14, 2006)

*Re: Are LEDs vulnerable to EMP?*



ADDICTED2LITE said:


> If tin foil will protect the light, why not the aluminum case the light is made of?


Because if there's an opening larger than the wavelength of the pulse, it can enter through there... and all flashlights have a fairly large plastic/glass/sapphire opening in one end.  Not to mention a reflector that (if metal) would focus the pulse right onto the LED itself.

Now, if there were a metal mesh electrically connected to the casing metal over that window, there might be a chance. Of course, depending on the strength of the pulse, the case might get darned hot....


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## soapy (Oct 14, 2006)

*Re: Are LEDs vulnerable to EMP?*

All depends on the power in the pulse. If it's a short but powerful blast it might fry it, it might not. If the voltage across the junction goes beyond the absolute maximum in the spec spec then it is dead for sure!

I'd be more worried about the radiation introducing too many defects so your LED that was once all shiny becomes a dim glow. Of course, I'd only be worried for a day at most, after than I'd be dead.


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## ringzero (Oct 14, 2006)

*Re: Are LEDs vulnerable to EMP?*



soapy said:


> I'd be more worried about the radiation introducing too many defects so your LED that was once all shiny becomes a dim glow. Of course, I'd only be worried for a day at most, after than I'd be dead.



Good point - the solid state stuff doesn't like ionizing radiation.

The frightening thing about EMP is that it could used as a weapon in its own right, not as a side effect.

One nuke detonated over Virginia at 150 miles altitude, could deliver a devastating EMP pulse to a good part of the Eastern seaboard. The resulting breakdown in power grids, transport, etc. would eventually kill more people than if the nuke had detonated in a city at ground level.


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## h_nu (Oct 14, 2006)

*Re: Are LEDs vulnerable to EMP?*

I would of course be more worried about radiation effects on me but I guess those empty butter cookie tins may need to be restocked with flashlights. Whoo hoo! Another place to hide my too large collection...


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## zelda (Oct 14, 2006)

*Re: Are LEDs vulnerable to EMP?*

Creating an emp is also possible without a nuke. 

Anyway, if something would happen, we falls at least 50 years back...

zelda


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## Ty_Bower (Oct 14, 2006)

*Re: Are LEDs vulnerable to EMP?*



TinderBox (UK) said:


> I read that a single layer of tin foil, the stuff you cook your roast in is all you need to protect all your electronic equipment from an EMP blast.


It's a good idea to keep plenty of tin foil around anyway. You need it to make a nice hat to keep out the government mind control rays.


----------



## billw (Oct 14, 2006)

*Re: Are LEDs vulnerable to EMP?*

I think y'all are watching too many movies. EMP might wipe out significant communications and power-grid stuff, but that's at least partially because you're
talking sensitive electronics and/or big antenas (or antenna-like arrays of wire.)
While I'm no nuclear expert, I'm pretty sure the scenario where random off-grid
elecronic appliances (like LED flashlights) fail in an impressive shower of sparks
is well beyond science fiction and into the realm of fantasy.


----------



## windstrings (Oct 14, 2006)

*Re: Are LEDs vulnerable to EMP?*

Well it would be nice to be able to use your light to see how crispy your skin is!


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## ringzero (Oct 14, 2006)

*Re: Are LEDs vulnerable to EMP?*



billw said:


> I think y'all are watching too many movies. EMP might wipe out significant communications and power-grid stuff, but that's at least partially because you're
> talking sensitive electronics and/or big antenas (or antenna-like arrays of wire.)



That's true. But, if the power grid over a big area of the country were to go down, it could take months to bring it back up.

Communications would be disrupted immediately. Ground transport would be hobbled by lack of traffic signals and fuel. Hospitals would black out within days. Food couldn't be transported into cities. There wouldn't be enough cops and National Guardsmen to keep things under control and anarchy would reign.



billw said:


> While I'm no nuclear expert, I'm pretty sure the scenario where random off-grid
> elecronic appliances (like LED flashlights) fail in an impressive shower of sparks
> is well beyond science fiction and into the realm of fantasy.



That's true. If close enough to be affected, solid state stuff would just stop working. No sparks, it just wouldn't work when turned on.


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## chesterqw (Oct 14, 2006)

*Re: Are LEDs vulnerable to EMP?*

what is the chances of an EMP blast that is powerful?

i reckon you can get the LED destroyed by static electricity then EMP.

static will damage LED !! remember


----------



## Radio (Oct 14, 2006)

*Re: Are LEDs vulnerable to EMP?*

If you are close enough that an EMP is going to take out your LED flashlight then you won't be around to worry about using it.


----------



## Sable (Oct 14, 2006)

*Re: Are LEDs vulnerable to EMP?*

Well, if I'm remembering my "EMP-ology" right, you would need a weapon of around 20 megatons (quite a lot larger - on the order of a thousand times - than the Hiroshima/Nagasaki blasts) and, yes, needs to be very high indeed.

Could an electromagnetic pulse event damage quite a lot of things? Yes, yes it could - but I've never considered it to be a huge threat to my daily life. This may be because I live in Alaska, where power is an iffy thing at best anyway.

There are non-nuclear ways to induce high-intensity EM fields, most of which cannot be used (or are impractical to) to launch far-ranging events.

Furthermore, you can protect EM-sensitive equipment with a Faraday cage, proper grounding, and other techniques.

I guess my point is that a "real" EM attack would likely be a significant event - but one that would be survivable by society and a reasonably well-prepared nation. There are ways of both seeing it coming and defending against it. Moreover, on my personal heirarchy of "things to worry about," it's not very high. But your mileage may, of course, vary.


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## The-David (Oct 14, 2006)

*Re: Are LEDs vulnerable to EMP?*



Ty_Bower said:


> It's a good idea to keep plenty of tin foil around anyway. You need it to make a nice hat to keep out the government mind control rays.



HAHAH And everyone though I was nuts wareing this thing around :tinfoil:


----------



## NewBie (Oct 15, 2006)

*Re: Are LEDs vulnerable to EMP?*



soapy said:


> All depends on the power in the pulse. If it's a short but powerful blast it might fry it, it might not. If the voltage across the junction goes beyond the absolute maximum in the spec spec then it is dead for sure!
> 
> I'd be more worried about the radiation introducing too many defects so your LED that was once all shiny becomes a dim glow. Of course, I'd only be worried for a day at most, after than I'd be dead.




Don't forget that CREE and Luxeon have a rather large ESD diode inside, that would greatly help to clamp that pulse from destroying the die. Usually this ESD diode is rated for 2,000 Volts. Also, the die is mounted above a "ground plane", which has capacitance, which will further help reduce the effects of the pulse.

EMP pulses are short, in the order of 100 billionths of a second, dropping to half amplitude within 200 billionths of a second, but there is low frequency energy that lasts up to 1000 seconds.

Also consider that the typical reflector opening size of an inch or so.
A wavelength at this diameter would be 1.18 GHz. Energy below this frequency would be greatly attenuated.

There are two major modes for EMP to get into equipment:
-Front Door Coupling occurs typically when power from a electromagnetic weapon is coupled into an antenna associated with radar or communications equipment. The antenna subsystem is designed to couple power in and out of the equipment, and thus provides an efficient path for the power flow from the electromagnetic weapon to enter the equipment and cause damage. 

-Back Door Coupling occurs when the electromagnetic field from a weapon produces large transient currents (termed spikes, when produced by a low frequency weapon ) or electrical standing waves (when produced by a HPM weapon) on fixed electrical wiring and cables interconnecting equipment, or providing connections to mains power or the telephone network . Equipment connected to exposed cables or wiring will experience either high voltage transient spikes or standing waves which can damage power supplies and communications interfaces if these are not hardened. Moreover, should the transient penetrate into the equipment, damage can be done to other devices inside. 

Notice how both modes for a significant amount of the pulse to get in, are mainly antennas and wiring.


There is one very specialized version of the EMP bomb, called a HPM, but they only have a small area of effect:

HPM weapons operating in the centimetric and millimetric bands offer an additional coupling mechanism. This is the ability to directly couple into equipment through ventilation holes, gaps between panels and poorly shielded interfaces. Under these conditions, any aperture into the equipment behaves much like a slot in a microwave cavity, allowing microwave radiation to directly excite or enter the cavity.

An example is that of a 10 GW 5 GHz HPM device illuminating a footprint of 400 to 500 metres diameter, from a distance of several hundred metres. This will result in field strengths of several kiloVolts per metre within the device footprint, in turn capable of producing voltages of hundreds of volts to kiloVolts on exposed wires or cables.

Now, how long is a flashlight like an HDS? 4 inches? So this will attenuate the voltage to 10th the voltage at 1 meter.

Anyone have the spectrum plot of what a large area EMP pulse weapon produces?

I know that in the case of a nuclear detonation, an electromagnetic pulse consists of a continuous frequency spectrum. Most of the energy is distributed throughout the lower frequencies between 3 Hz and 30 kHz. As such, most metal LED flashlights would be rather safe. There is a weaker initial spike at the first time of arrival from 1 to about 300 MHz caused by gamma radiation. Following that, there is energy from 1 to 100KHz which lasts a total of about 1 millionth of a second. Then there is a bunch of low frequency activity, that mainly threatens long power lines, data lines, and antenna cables, that goes on for up to 1000 seconds.

Also, realize the strength of the pulse drops with the distance from the detonation. For more info on this look here:
http://electromagneticpulse.quickseek.com/


In the case of a EMP bomb at altitude, typically, the field strength on the ground drops to 300 volts per meter at only 3 miles from the burst, at ground level.

Did you know that the effect of a altitude EMP burst, once you get away from "ground zero", on the ground follows a boomerang shape, and the peak field is in the V of the boomerang, which is always pointed south? And it is very weak to the North. This is due to the earth's magnetic field.

More detailed info here:
http://www.usace.army.mil/publications/eng-pamphlets/ep1110-3-2/c-2.pdf


----------



## ciam (Oct 15, 2006)

*Re: Are LEDs vulnerable to EMP?*

I'm not sure exactly what fellow CPFer "etc" referred to. If it's really the ultra high intensity EM radiation burst produced by nuclear bombs or other more mundane means, I would worry more about myself than my LED flashlights, for example, mutating genes in my cells or causing havoc in my brain circuit....

If it's the gentler EM radiations you encounter in your daily life, there isn't much to worry about. Indeed, a shake LED flashlight is usually equipped with a magnetic coil. While you should be careful to keep it away from your electronic devices, the LED inside is happly sitting in the rather strong magnetic field.


----------



## vic303 (Oct 15, 2006)

*Re: Are LEDs vulnerable to EMP?*

Nice info, NewBie! 
Here is some info from the Amateur Radio Relay League on EMP.

http://www.arrl.org/tis/info/pdf/88615.pdf
http://www.arrl.org/tis/info/pdf/98622.pdf
http://www.arrl.org/tis/info/pdf/108638.pdf
http://www.arrl.org/tis/info/pdf/118630.pdf


And something from another ham radio site.


http://www.qsl.net/n9zia/emp.html


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## IsaacHayes (Oct 15, 2006)

*Re: Are LEDs vulnerable to EMP?*

I've heard that even pole transformers can be taken out by EMP! now that's crazy!

I don't think we have to worry much about it. There would be much worse problems if an EMP was to go off...


----------



## AlexGT (Oct 15, 2006)

*Re: Are LEDs vulnerable to EMP?*

Is there a practical way to create big EMP without the use of nukes? Can an EMP be directed like a ray? I was thinking if we could do that maybe the police chases would end, just EMP the speeding car to make it stop since all are computer controlled.

AlexGT


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## ciam (Oct 15, 2006)

*Re: Are LEDs vulnerable to EMP?*

EMP could be produced by any big explosions, not necessarily nuclear explosions. It could also be produced by a rapidly fluctuating magnetic field. But I doubt it could be deployed in the manner you described.


----------



## NewBie (Oct 15, 2006)

*Re: Are LEDs vulnerable to EMP?*



IsaacHayes said:


> I've heard that even pole transformers can be taken out by EMP! now that's crazy!




They have wires hooked to them that go on for miles. Makes for very efficient antennas to couple the EMP pulse into them...


----------



## Sub_Umbra (Oct 15, 2006)

*Re: Are LEDs vulnerable to EMP?*

I'm not worried about EMP's effect on flashlights. 

If the LEDs in your flashlights (with your flashlights *minescule* antenna length) are knocked out by EMP the blast would have to be huge. There wouldn't be any power grid left at all -- with it's antenna length *billions of times* the length of our lights. Anything connected to the grid would be gone forever.

Anything electronic in *all* cars (again, with an effective antenna length many, many times longer than any of our lights) would also be toast.

Those are pretty big ifs, IMO. This is the kind of thing that makes the news, _but only on very slow news days._ 

I don't buy the premise. Sure, it's probably possible to generate *a powerful enough EMP* that _could_ damage an LED flashlight *with it's tiny effective antenna length* but even then the light would have to be *in very close proximity* to the source of the pulse to be affected.

If the EMP takes your flashlight, build a fire -- because the power grid will be gone for years...if it *ever* comes back.


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## wasBlinded (Oct 16, 2006)

*Re: Are LEDs vulnerable to EMP?*



AlexGT said:


> Is there a practical way to create big EMP without the use of nukes? Can an EMP be directed like a ray? I was thinking if we could do that maybe the police chases would end, just EMP the speeding car to make it stop since all are computer controlled.
> 
> AlexGT


 
Exactly such a technology is in use by law enforcment today. It is a device laid in the road in the path of a vehicle, triggered by its passage.


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## soapy (Oct 16, 2006)

*Re: Are LEDs vulnerable to EMP?*

There is a radio jammer system that does that, but I can't find a reference anywhere. I thought it was a gun device that they pointed, like a radar gun on steroids. It basically interfers with the car electronics by introducing noise into the system, causing misfires and problems. Of course, a diesel truck wouldn't notice it, and a really new car with drive-by-wire might steer off course, or even go faster as all the systems are jammed.

However, that's not EMP, since the device isn't a single power pulse that destroys things, it's more like a radio jammer in that when you turn it off the system resets to normal.


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## lyyyghtmaster (Oct 16, 2006)

*Re: Are LEDs vulnerable to EMP?*

With regards to the power grid issue, and EMPs of a more modest size than some discussed here: It seems that some areas of the country would be better protected than others (think those areas hardened to protect against frequent lightning). This could create a situation of mass migration as people innundate regions comparatively protected from the EMP effects by the islanding that would (hopefully!) occur when more vulnerable sections of the grid (and/or closer to the pulse) were taken out by EMPs. Just offering another cheery thought! (But at least our lights would probably remain unaffected!):candle:


----------



## joema (Oct 16, 2006)

*Re: Are LEDs vulnerable to EMP?*

If you're talking about a nuclear EMP, it's easily possible many or most unshielded microprocessor-based devices within hundreds of miles could fail. The peak field strength could be 50,000 volts per meter. Diodes (inc'l LEDs) might not be damaged, but microprocessors with their vastly smaller semiconductor gates are more sensitive.

So your direct-drive LED lights might work, but anything with a microprocessor or microcontroller might not. That would include most cars, computers, radios, TVs, wrist watches, camcorders, cell phones, electronic medical equipment, etc.

It also doesn't require a deadly close nuclear EMP to cause this. A high altitude detonation that causes no harmful ionizing radiation to humans could still destroy many semiconductors. Peak field strength might be 50,000 volts per meter, over a large area: http://en.wikipedia.org/wiki/Electromagnetic_pulse

The problem isn't surviving an EMP attack or the secondary blast and radiation from the nuke that generates the EMP. High altitude nuclear bombs have already been detonated in space, and they didn't harm people beneath them: http://en.wikipedia.org/wiki/Starfish_Prime

Rather the problem is there's little rational basis for a stand-alone nuclear EMP attack. It would most likely be part of a larger attack, probably a 1st action to disrupt communication and coordination, which would be followed by a _real_ nuclear attack.

So in a sense the people saying an EMP attack would be disastrous are correct, but not from the nuclear-pumped EMP itself. There would be no mutations or radiation-induced deaths from a high altitude nuclear EMP. We know that because several of those have already happened: http://en.wikipedia.org/wiki/High_altitude_nuclear_explosion Rather the destruction would come from the _actual_ nuclear attack, which would would likely immediately follow the EMP strike.


----------



## NewBie (Oct 16, 2006)

*Re: Are LEDs vulnerable to EMP?*



joema said:


> If you're talking about a nuclear EMP, it's easily possible many or most unshielded microprocessor-based devices within hundreds of miles could fail. The peak field strength could be 50,000 volts per meter. Diodes (inc'l LEDs) might not be damaged, but microprocessors with their vastly smaller semiconductor gates are more sensitive.




Hundreds of miles is a very small area. Keep in mind, that natural features will also help to shield against the pulse, and as I'd mentioned, there are quite a number of factors that would help a lot, in metal flashlights, to protect both the LED and the electronics.

I do know that a sample of one, an ARC4+, had no issues at all, with 300 V/m, at frequencies below 1 GHz, when I tested it. It didn't even phase it, when it was off or when it was on.


There are more details in the US Army document on the subject here:

http://www.usace.army.mil/publications/eng-pamphlets/ep1110-3-2/c-2.pdf


----------



## Jedi Knife (Oct 16, 2006)

*Tin foil?*

Do they even still make tin foil? I thought they stopped producing tin foil years ago.


----------



## joema (Oct 19, 2006)

*Re: Are LEDs vulnerable to EMP?*



NewBie said:


> Hundreds of miles is a very small area. Keep in mind, that natural features will also help to shield against the pulse, and as I'd mentioned, there are quite a number of factors that would help a lot, in metal flashlights, to protect both the LED and the electronics...


That was a radius figure, not area. It's 50,000 volts/meter over roughly 50,000 square miles, and 37,500 volts/meter over about 1/3 the continental US -- from a single detonation.

As already stated, not sure the emitter itself would be damaged, but anything with a microcontroller or microprocessor is at more risk.

Like many flashlights, most airplane skins are solid metal with just a few apetures. However the Air Force built this gigantic facility to test how B-52s can withstand EMP: http://www.brook.edu/FP/projects/nucwcost/trestle.htm

This article discusses EMP from standpoint of energy (joules) per unit area, not volts per meter: http://www.measurement-testing.com/electromagnetic-pulse.html

It says 1 joule can be EMP-coupled to many systems, yet only 10^-13 joules (one 10 trillionth of that) can upset some semiconductors.

But my main point was the posters saying EMP is no problem since you'd be dead from blast/heat/gamma radiation are incorrect. There have been numerous high altitude and space nuclear detonations in the late 1950s and early 1960s. They generated plenty of EMP, and people didn't die. Unfortunately submicron gate semiconductors didn't exist then, so there's no actual empirical data from real nuclear EMP about their sensitivity.

But there's little tactical purpose of a nuclear-pumped EMP without an immediate follow on nuclear strike, so in a sense the people saying "we're doomed anyway, what's the point" may be correct.


----------



## h_nu (Oct 19, 2006)

*Re: Tin foil?*



Jedi Knife said:


> Do they even still make tin foil? I thought they stopped producing tin foil years ago.



I'm pretty sure you are right. Many Americans use the term "tin foil" when they really mean Aluminum foil. People raised in the 40's and 50's called it that and their children probably flunked chemistry.


----------



## :)> (Oct 19, 2006)

*Re: Are LEDs vulnerable to EMP?*



TinderBox (UK) said:


> I read that a single layer of tin foil, the stuff you cook your roast in is all you need to protect all your electronic equipment from an EMP blast.
> 
> regards.
> 
> John.



You can also use tin foil around your head to keep the aliens from reading your thoughts

-Goatee


----------



## NewBie (Oct 21, 2006)

*Re: Are LEDs vulnerable to EMP?*



joema said:


> That was a radius figure, not area. It's 50,000 volts/meter over roughly 50,000 square miles, and 37,500 volts/meter over about 1/3 the continental US -- from a single detonation.
> 
> As already stated, not sure the emitter itself would be damaged, but anything with a microcontroller or microprocessor is at more risk.
> 
> ...




Actually it says:
" Nevertheless, EMP is still capable of transferring something of the order of 0.1 - 0.9 joule/m2"

As I pointed out earlier, you need something to pick up this energy. I can in fact expose an unprotected luxeon in free space, with nothing attached, to a field 36,000 V/m continously and see zero damage to the device.

Now take a look at the frequency distribution of an EMP pulse.

Lets think about something common like the HDS light. Surround a luxeon on all sides, but one, with thick aluminum. Next take a metal reflector, and essentially plug that hole with the luxeon. Go look up the frequency distribution of the EMP pulse at ground level. For a high altitude burst, that would cover CONUS, many references will say that 99% of it falls below 100MHz. You are looking at wavelengths that are roughly one meter long. Consider this again, and compare it to the reflector size, and then realize, hardly any is going to even enter the reflector at all, as it's wavelength is way too long. What magnetic field makes it thru the aluminum, remember all the wiring is quite short, and also, HDS utilizes a shielded ferrite inductor, which if was unshielded (and it is not unshielded), would be a primary point for the field to couple in at.

When folks wax and wane on, saying there were effects as far away as Hawaii, keep in mind, this was primarily coupled in by the long wires of the power grid, which serve as very nice antennas.

I've participated in equipment testing, such as indirect lighting, direct lighting, and various electromagnetic field testing. One of the hardest things to protect against is that wiring that is strung out, and how it couples into the system, serving as wonderful collectors and antennas. Seams can be overlapped as necessary, or even folded to get more effect. Consider that the HDS has a multi-fold design which is present in it's threads.

This reminds me of the time a while back, when an EA-6B Prowler accidentially jammed the flight controls of a F/A-18 aircraft. Luckily the ECMO realized what had happened, and shut down their ALQ-99 system, allowing the F/A-18 pilot to regain control of his aircraft. Even though the F/A-18 had passed all the high energy testing, including a variety of EMP pulses, the ALQ-99 jamming system had a very concentrated high power (above a kilowatt) beam of frequencies in the multiple GHz range, and they managed to easily couple into the F/A-18's flight control computer, thru the aircraft wiring. The source of entry was the seams of the aircraft skin, which nicely passed the offending source into the body of the aircraft, and on to the wiring. The fix? Just some simple low cost EMI fingers that ran around under the edge of the panels.


----------



## Jedi Knife (Oct 21, 2006)

*Re: Tin foil?*



h_nu said:


> I'm pretty sure you are right. Many Americans use the term "tin foil" when they really mean Aluminum foil. People raised in the 40's and 50's called it that and their children probably flunked chemistry.



Wow. It's amazing that people simply parrot out things that they hear instead of applying some thought to what they're saying. I would have thought that inhabitants of the most advanced country in the world would know better. To think that these same people are posting advice in such a technical thread as this is hilarious.


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## OCEANBEAMER (Oct 21, 2006)

*Re: Are LEDs vulnerable to EMP?*

pehaps we should all store our lights in a faraday box just in case of emp.


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## ringzero (Oct 22, 2006)

*Re: Tin foil?*



Jedi Knife said:


> Wow. It's amazing that people simply parrot out things that they hear instead of applying some thought to what they're saying. I would have thought that inhabitants of the most advanced country in the world would know better. To think that these same people are posting advice in such a technical thread as this is hilarious.



On the other hand, there's nothing wrong with people using slang to express themselves. CPF isn't some dry technical publication, and that is part of its charm.

"Tin foil" for aluminum foil, "Ice Box" for refrigerator, "powder" or "gunpowder" for smokeless propellant, and numerous other commonly used terms are all technically incorrect. But, anachronism is part of their appeal.


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## hank (Oct 22, 2006)

*Re: Are LEDs vulnerable to EMP?*

Any of you old enough to remember when we all of a sudden changed our minds about invading Cuba the last time 'round? That's when the US and USSR found out what they could do to themselves without any surface targets being hit.

Both rattled their sabers in their sheaths to make threatening noises, and discovered it made their pants fall down. Oops.

This link was posted earlier in the thread; here's a brief excerpt:

http://en.wikipedia.org/wiki/High_altitude_nuclear_explosion

"... The Soviets detonated four high-altitude tests in 1961 and three in 1962. During the Cuban Missile Crisis in October 1962, both the US and the USSR detonated several high-altitude nuclear explosions as a form of sabre-rattling. The Soviet tests were meant to demonstrate their anti-ballistic missile defences which would supposedly protect their major cities in the event of a nuclear war. The worst effects of a Russian high altitude test occurred on 22 October 1962 (during the Cuban missile crisis), in ‘Operation K’ (ABM System A proof tests) when a 300-kt missile-warhead detonated near Dzhezkazgan at 290-km altitude. The EMP fused 570 km of overhead telephone line with a measured current of 2,500 A, started a fire that burned down the Karaganda power plant, and shut down 1,000-km of shallow-buried power cables between Aqmola and Almaty [5]. The Partial Test Ban Treaty was passed the following year, ending atmospheric and exoatmospheric nuclear tests. "

Communications gear nowadays is a bit more sensitive -- remember:

Solar flares will disrupt GPS in 2011 - tech - 29 September 2006 ...
Charged particles from solar flares also produce intense bursts of radio noise, which peak in the 1.2 and 1.6 gigahertz bands used by GPS. ...
www.newscientisttech.com/article/dn10189


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## mchlwise (Feb 17, 2007)

*LED flashlights and E.M.P. vulnerability - thoughts?*

This may sound like a strange question, but...

With all that's going on in the world, Iran getting close to going nuclear, terrorism, world politics, etc., something's been on my mind lately: 

It seems like the U.S. and our insatiable appetite for electricity and all things electronic make us particularly vulnerable to E.M.P. and an E.M.P. attack.

(for those unfamiliar - an atomic/nuclear bomb, when detonated, produces an Electro-Magnetic Pulse. This pulse destroys anything and everything electronic in the path of the pulse. A nuclear bomb detonated at 400km over the center of the country would destroy all electronic devices (including cars) in nearly all of the country. E.M.P. can also be generated from non-atomic sources. http://en.wikipedia.org/wiki/Electromagnetic_pulse)

My question is: *how vulnerable are LEDs and LED flashlights to E.M.P.? *

At first it may seem like a simple question, but there are a number of factors that make it more complicated once fully examined. 

For example: the best defense against E.M.P. is to enclose the electronic equipment in metal on all sides, creating in effect Faraday cage. As long as the equipment is insulated from the metal, the E.M.P. will travel around it and dissipate. 

Would the aluminum body of a light like a Fenix act as a Faraday cage and protect the LED? 

Would an aluminum reflector focus the E.M.P. onto the LED intensifying its effect? 

Are emitters like Luxeons and Crees even vulnerable to effects of E.M.P.?

What about the electronics/circuit boards/drivers? If the emitters aren't vulnerable, and the driver is, the light would still be destroyed. 

:shrug: 

So what are everyone's thoughts? 



p.s. - I've asked Gransee about the Arc AAA-P and E.M.P., and he indicated they have actually tested it and the Arc withstood and survived E.M.P. BUT, the single-mode Arc with a 5mm emitter seems to me like a whole different animal than a JetBeam or a L1dce.


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## Valpo Hawkeye (Feb 17, 2007)

*Re: LED flashlights and E.M.P. vulnerability - thoughts?*

I've often wondered about this myself. My guess, and it's just that, a guess, is that lights like HDS EDC's and other circuit-driven lights would be vulnerable. Direct drive led's like an Arc AAA might be okay. But I'm not sure, so this post is pretty worthless...


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## h_nu (Feb 17, 2007)

*Re: LED flashlights and E.M.P. vulnerability - thoughts?*

This comes up from time to time and thankfully we haven't had a real world test yet. 

The tinfoil hat types might want to keep their lights in empty Danish butter cookie tins. Mmmmm, butter cookies.


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## tebore (Feb 17, 2007)

*Re: LED flashlights and E.M.P. vulnerability - thoughts?*

It's been discussed that an EMP strong enough to damage your flashlight would be the least of your concerns. Strong EMPs are usually caused by Nukes which would turn you into red vapor. 

Power LEDs like Luxeons have built in ESD protection which might help.

EMPs would kill incans as well because a surge would break the filament. 

The Arc AAA is not direct drive it has a boost circuit. 

Again if an EMP struck, a non working flashlight would be the least of your concerns.


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## TORCH_BOY (Feb 17, 2007)

*Re: LED flashlights and E.M.P. vulnerability - thoughts?*

It depends on the Flashlight, most modern lights use a circuit or proccessor circuit
of some description, EMP would probably destroy the circuit. Thats the advantage of
direct incadescent lights


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## Rubycon (Feb 17, 2007)

*Re: LED flashlights and E.M.P. vulnerability - thoughts?*

Anyone willing to put their lights in the microwave and try it out?

The EMP in the ring of a can crusher is pretty intense as well.


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## VidPro (Feb 17, 2007)

*Re: LED flashlights and E.M.P. vulnerability - thoughts?*

the inductor coil would be the most susceptable thing to a magnetic pulse, which then might be capable of outputting enough juice to damage the led if it was on, or if the pulse jumped the switching.
the led (itself) doesnt make much of a receptor for any magnetic pulsing.
emp wants transformers, long wires, and stuff that Already uses magnatism in its actions, something that can get the pulse. things that would act like transformers.

your induction charger on your toothbrush is more likely to fail. but then again your teeth will be all falling out of your head, and so it wont really be an issue.

most motors have coils that use and would be directally effected by magnetic pulses, as they work on that principal, if your flashlight doesnt have a starter motor, or a alternator, or 500Feet of exposed (transformer like) wiring, then its going to outlast your car.

doesnt the "shielding" have to be Ferrous? and not add to or concentrate the magnatism, like the 2 hunks of metal on both sides of a cheap magnet.

i think if you tossed out the curcuit, the led flashlight would be as capable of surviving as, , say your toaster.

many more consumer electronics things have so much more potential for failing on a magnetic pulse, especially stuff tied to the "grid", which is a big collector.


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## AC_Doctor (Feb 17, 2007)

*Re: LED flashlights and E.M.P. vulnerability - thoughts?*



h_nu said:


> The tinfoil hat types might want to keep their lights in empty Danish butter cookie tins. Mmmmm, butter cookies.


 
Just make sure that the butter cookie tin has a dedicated ground wire, or the tin will be worthless against the EMP...

AC


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## elgarak (Feb 17, 2007)

*Re: LED flashlights and E.M.P. vulnerability - thoughts?*



h_nu said:


> This comes up from time to time and thankfully we haven't had a real world test yet.


Unfortunately, we had. That's how the effect was found. Though the kind of electronics around at the time was much less sensitive than modern semiconductors.


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## qip (Feb 17, 2007)

*Re: LED flashlights and E.M.P. vulnerability - thoughts?*

broken arrow was on tv today  and they nuked underground, all people above lived ok but the electronics still fried


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## 65535 (Feb 17, 2007)

*Re: LED flashlights and E.M.P. vulnerability - thoughts?*

Only things that could be damaged are IC's mostly uC's inductor but other than that ESD isn't the same as EMP which would only cuase an ESD if there was and inductor which for most lights there is one. I would be willing to be that any EMP large enough to damage a flashlight would come from a source making the Flashligh damage the least of your worries


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## TIP AND RING (Feb 17, 2007)

*Re: LED flashlights and E.M.P. vulnerability - thoughts?*

There are no definitive answers. Most all of the worlds testing has been small scale and any related data has not been released for public consumption. There are many means for creating a EMP event without the use of nuke devices. There are a few sites with creative information. Such as : http://www.endtimesreport.com/EMP.html As with all web information, perhaps 10% of this sites information is valid. The rest remains pure speculation, conjecture, opinion and the normal, internet, armchair "experts".


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## FlashKat (Feb 17, 2007)

*Re: LED flashlights and E.M.P. vulnerability - thoughts?*

Like tebore said it has been discussed on another thread, and you would die before the flashlight does...So be happy you are alive today to enjoy your flashlights. :laughing:


tebore said:


> It's been discussed that an EMP strong enough to damage your flashlight would be the least of your concerns. Strong EMPs are usually caused by Nukes which would turn you into red vapor.
> 
> Power LEDs like Luxeons have built in ESD protection which might help.
> 
> ...


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## elgarak (Feb 17, 2007)

*Re: LED flashlights and E.M.P. vulnerability - thoughts?*



TIP AND RING said:


> There are no definitive answers. Most all of the worlds testing has been small scale and any related data has not been released for public consumption. There are many means for creating a EMP event without the use of nuke devices. There are a few sites with creative information. Such as : http://www.endtimesreport.com/EMP.html As with all web information, perhaps 10% of this sites information is valid. The rest remains pure speculation, conjecture, opinion and the normal, internet, armchair "experts".


BS. Google Scholar finds 300,000 hits in scientific papers. The effect is scientifically published and tested. Similar effects threaten commercial spacecraft (satellites), so a lot of testing is done with and by the scientific community, although not testing with nukes . (The EMP can be done without nukes).

I disagree with the notion that you would die; the EMP of a high altitude nuke affects a far larger area than the biological threatening effects. Which is why the EMP is of such high interest. Win a war without killing people.


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## Skibane (Feb 17, 2007)

*Re: LED flashlights and E.M.P. vulnerability - thoughts?*

The strength of the electrical spike induced by an EMP (which is what causes damage to a circuit) is dependent on the length and physical orientation of any conductors connected to the circuit. Long conductors (i.e., AC power lines, phone lines, big antennas, etc.) incercept a significant percentage of the EM pulse; short conductors do not.

In circuits that aren't connected to any long conductors, virtually no electrical spike is generated due to EMP, and *the circuit is unlikely to be damaged*. Almost all flashlights (LED and otherwise) would fall into this category - as would many other small electronic devices (i.e., cell phones, portable radios, PDAs, laptop computers, digital wristwatches, etc.). The few inches (or fractions of an inch) of conductors present in these devices is simply too short to intercept any significant amount of the EM pulse, and thus no damaging voltage spike is generated within them.

Several practical examples:

1. During the Starfish Prime high-altitude nuclear test conducted on July 9, 1962, it was reported that EMP effects caused damage to streetlights in Hawaii (some 930 miles away), and yet portable radios located on Johnson Island (located immediately under the nuclear burst) were undamaged. Explanation: The portable radios lacked any large antennas or other connections to long conductors, and thus didn't receive enough of a spike to be damaged.

2. The American Radio Relay League (ARRL) published a series of articles that described the effects of EMP on various communication equipment:

Intro to EMP
EMP Protection Devices
EMP Implications for Communications
EMP Protection for Communications

These tests demonstrated that equipment which lacks any connections to long conductors is unlikely to be damaged by EMP.

BOTTOM LINE: There are a lot of urban legends, half-truths and complete falsehoods about EMP floating around on the internet. In general, the potential damage is greatly exaggerated (particularly for small, portable electronics).


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## nightshade (Feb 17, 2007)

*Re: LED flashlights and E.M.P. vulnerability - thoughts?*

Right on.. Google Scholar pays my bills. I am a armchair expert and a willing participant of all that is truthful on CPF. No problem with BS either.


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## TIP AND RING (Feb 17, 2007)

*Re: LED flashlights and E.M.P. vulnerability - thoughts?*



elgarak said:


> BS. Google Scholar.


 
Exactly. No real world experts here, as I stated. This includes me.


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## FASTCAR (Feb 17, 2007)

*Re: LED flashlights and E.M.P. vulnerability - thoughts?*

Worry more about a pure nuke then a EMP only bomb.A nuke also has an EMP wave.


If your close enough for the EMP to effect you...the 600 mph wind or tempature will be the bulk of your problem.


Fascars says : U cant use a light when your dust.


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## Mudd Magnet (Feb 17, 2007)

*Re: LED flashlights and E.M.P. vulnerability - thoughts?*

I have often wonderd the same thing abought these led flashlights and the effects of a emp attack. If the shi! hits the fan the last thing I want to worrie abought is my light not working I would be more concernd with what is going on in the immediate area and around the house it would be no fun preparing stuff in the dark especially when you are stressed out to the max abought what just happend and what the next week month year holds. as others have pointed out it is not just nuclear bombs to be worried abought although a downed power grid over much of the states or canada would most likely end up nearly as bad :shakehead


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## cage (Feb 18, 2007)

*Re: LED flashlights and E.M.P. vulnerability - thoughts?*

I think that the metal casing of the lamp might protect it from harm.


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## VidPro (Feb 18, 2007)

*Re: LED flashlights and E.M.P. vulnerability - thoughts?*

well you know the sky does get Black when all heck breaks loose, however all heck breaks loose, so a working light might be usefull if it could see past the smoke.


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## r0b0r (Feb 18, 2007)

*Re: LED flashlights and E.M.P. vulnerability - thoughts?*

/me plans to fit out a submersible waterproof, faraday caged mega-SHTF case


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## BentHeadTX (Feb 18, 2007)

*Re: LED flashlights and E.M.P. vulnerability - thoughts?*

BOOM! (Pulse of EMP)

What a day... missed the aircraft crashing around me, the electrical grid going down and the car won't start. Hop on my bicycle and pedal to work while noticing my speedometer does not work. Fire up my L1D CE on the helmet to light my way but the plastic rear flashers are dead.  

Enter the building through a maintenance door (mechanical lock) and make it to my bench. The ESD grounded Stanley-Vidmar bench is easy to spot by the light of my helmet. Pull out the drawer and test my Peaks and they all work. Remove the lights, spare batteries and 12V chargers and leave. Check my computer and the servers are down 

Ride home and take stock of batteries, food and water and pull the laptop out of the aluminum case. Fire it up and it works!  Click on the Firefox icon and receive "wireless LAN not connected"  Throw the laptop in my rear rack bag on the bicycle and ride back to work to patch directly to the underground server. 

Viola! I have a connection! God bless 2 meters of rebar reinforced concrete! Wait...wait...WAIT! CPF is down and so is the underground lifeline! Time passes and the chaos builds and my batteries start running out... my precious LEDs start emitting their last photons... CPF stays down and we have truely reached the end of the world as we know it. 

I walk around the rubble using a wooden torch talking about how different asphault types can increase output and oak has a longer burn time than pine although not as bright. My EDC becomes a Zippo...


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## NewBie (Feb 18, 2007)

*Re: LED flashlights and E.M.P. vulnerability - thoughts?*

The old thread is here:
https://www.candlepowerforums.com/threads/136969&highlight=EMP

Keep in mind, if you are one of the highly paranoid types, you can use closed, or shielded inductor, which should help when compared to an open inductor. Of course, at the higher frequencies, which comprise a lot of the EMP pulse (well, it depends on what time you look at the pulse, since it changes, and also changes with distance), many ferrites used in power inductors don't work all that well, and then there is the interwinding capacitance and other factors...


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## LowBat (Feb 18, 2007)

*Re: LED flashlights and E.M.P. vulnerability - thoughts?*

I'd like to have a device that produces directional EMP waves for those “considerate challenged” drivers that over-crank the bass on their car stereos.


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## r0b0r (Feb 18, 2007)

*Re: LED flashlights and E.M.P. vulnerability - thoughts?*



LowBat said:


> I'd like to have a device that produces directional EMP waves for those “considerate challenged” drivers that over-crank the bass on their car stereos.



If you're a sociopath, a 1kW+ magnetron (hooray for microwave ovens!) with a waveguide might do the trick...

I wonder how well those things perform over a ~10m range?


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## SEMIJim (Feb 18, 2007)

*Re: LED flashlights and E.M.P. vulnerability - thoughts?*



tebore said:


> It's been discussed that an EMP strong enough to damage your flashlight would be the least of your concerns. Strong EMPs are usually caused by Nukes which would turn you into red vapor.


Not true. The most effective EMP burst is so far up that you would be unaffected by the direct blast.



tebore said:


> Power LEDs like Luxeons have built in ESD protection which might help.


ESD is not the same thing as EMP. EMP is electro-_magnetic_ in nature, not electro-_static_.



tebore said:


> EMPs would kill incans as well because a surge would break the filament.


I don't think so, Tim. Nor would vacuum tubes be affected. Only solid-state gear is affected by EMP. And things with very large "antennas," such as power grids.



tebore said:


> Again if an EMP struck, a non working flashlight would be the least of your concerns.


Probably so--until the sun went down, at least 

You want to survive an EMP burst? Live outside the city, drawing your own water and using a septic field. Have a wood-burning stove for heat. Have candles, kerosene lanterns and incandescent flashlights for light. Have an old car (probably pre-1970) that doesn't have electronic ignition. Have old vacuum tube radios and TVs. (No remote for that TV, either.) A gasolene-powered generator, non-electronic, would probably survive. But the gasolene supply won't last. Of course: If you're prepared to survive the EMP, and you do, then you have to be prepared to suvive the aftermath. Given that you'd be one of the exceedingly few that survived with any of civilization's amenities intact, and the number of vultures that wouldn't have, well... I'm not certain there'd be a point. Not unless you were _very_ isolated and _very_ vigilent.


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## SEMIJim (Feb 18, 2007)

*Re: LED flashlights and E.M.P. vulnerability - thoughts?*



Skibane said:


> 1. During the Starfish Prime high-altitude nuclear test conducted on July 9, 1962, it was reported that EMP effects caused damage to streetlights in Hawaii (some 930 miles away), and yet portable radios located on Johnson Island (located immediately under the nuclear burst) were undamaged. Explanation: The portable radios lacked any large antennas or other connections to long conductors, and thus didn't receive enough of a spike to be damaged.
> ...
> BOTTOM LINE: There are a lot of urban legends, half-truths and complete falsehoods about EMP floating around on the internet. In general, the potential damage is greatly exaggerated (particularly for small, portable electronics).


The problem with applying the Starfish Prime experience to today is that, back then, electronics were relatively crude and high-power, by today's standards. Today, the drive for more capabilities and features, in smaller packages and with longer-runtimes, has given us low-power electronics that are _far_ more susceptible to electronic pulses than was the crude, simple transistor radio. Even the ARRL articles are now more than 20 years out-of-date.

I agree that the threat is greatly misunderstood and greatly exaggerated, but I still wouldn't want to be dependent on "civilization"s infrastructure and conveniences in the event of an effective EMP burst.


----------



## SEMIJim (Feb 18, 2007)

*Re: LED flashlights and E.M.P. vulnerability - thoughts?*



r0b0r said:


> If you're a sociopath, a 1kW+ magnetron (hooray for microwave ovens!) with a waveguide might do the trick...


No need to fry the occupents to wax their noise system. You just need to generate a sharp, intense electromagnetic pulse. IIRC, I once saw on TV a demonstration of a device with military application that was basically an electromagnetic pulse gun. Non-lethal to life, but destructive to electronics.


----------



## flashy bazook (Feb 18, 2007)

*Re: LED flashlights and E.M.P. vulnerability - thoughts?*

wow - only on CPF would one find information like this!

My worry (well, one of many, actually) is that LED's are semiconductor devices which ARE susceptible to EMP's.

Just like the old info. that vacuum tubes survive EMPs, no problem, but the newer radios don't, wouldn't LED's just die? Since they are semi-conductors and semi-conductors are affected by an EMP?

I realize that the electrical circuits themselves could suffer damage, but isn't even that fact secondary if the LED itself is vulnerable?


----------



## LowBat (Feb 18, 2007)

*Re: LED flashlights and E.M.P. vulnerability - thoughts?*



SEMIJim said:


> No need to fry the occupents to wax their noise system. You just need to generate a sharp, intense electromagnetic pulse. IIRC, I once saw on TV a demonstration of a device with military application that was basically an electromagnetic pulse gun. Non-lethal to life, but destructive to electronics.


Well I know I can't get an EMP gun, but my other idea (provided they were listening to am/fm or satellite) was to direct a strong signal and override their music selection with something that assaults their ears to the same degree they were doing to mine. Perhaps the sudden blast of William Shatner singing "Mr. Tambourine Man" or "Lucy in the Sky with Diamonds" coming from their speakers would be equal justice.

Getting back on topic, I believe I read somewhere years ago that circuits could be protected from EMP waves. I just don't remember how the military accomplished this.


----------



## Vickers (Feb 18, 2007)

*Re: LED flashlights and E.M.P. vulnerability - thoughts?*

No need for flashlights post-Apocalypse....everything will be glowing. :rock:


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## petersmith6 (Feb 18, 2007)

*Re: LED flashlights and E.M.P. vulnerability - thoughts?*

just wait till we get hit by giant sunspots and solar flaires..stonage here we come.and NO american idol/pop idol...bring it on!!!!!the reliance on electonics will at some point be mans down fall.then were will of the afriaca to relearn all we have forgoton.


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## Sierra_Bill (Feb 18, 2007)

*Re: LED flashlights and E.M.P. vulnerability - thoughts?*



FASTCAR said:


> Worry more about a pure nuke then a EMP only bomb.A nuke also has an EMP wave.
> 
> 
> If your close enough for the EMP to effect you...the 600 mph wind or tempature will be the bulk of your problem.
> ...



You might try reading the other posts. EMP is an issue with nuclear explosions at altitude. One nuclear explosion in the upper atmosphere or space would have little or no biological effect but would devastate electronics. This would be a tactic to cripple a country and defeat them militarily without killing vast numbers of people... at least not directly. As others have suggested, the consequences of a collapse of civilization, even if only in the U.S., would be very bad. Your flashlights that still worked would be useful for a time, but they would not fend off armed predators of the two-legged kind, nor would they grow food.

Bill D.


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## orionlion82 (Feb 18, 2007)

*Re: LED flashlights and E.M.P. vulnerability - thoughts?*



SEMIJim said:


> No need to fry the occupents to wax their noise system. You just need to generate a sharp, intense electromagnetic pulse. IIRC, I once saw on TV a demonstration of a device with military application that was basically an electromagnetic pulse gun. Non-lethal to life, but destructive to electronics.





you mean like a high voltage discharge, like lightning, or capacitors or tesla coils. yes, there are people out there who build their own capacitors in trash barrels and zap the bezeezus out of stuff for fun... .
as well as a few weapons without teh nucs.

EDIT: good luck on a vehicle mounted system that is both safe and legal...


----------



## Skibane (Feb 18, 2007)

*Re: LED flashlights and E.M.P. vulnerability - thoughts?*



SEMIJim said:


> The problem with applying the Starfish Prime experience to today is that, back then, electronics were relatively crude and high-power, by today's standards. Today, the drive for more capabilities and features, in smaller packages and with longer-runtimes, has given us low-power electronics that are _far_ more susceptible to electronic pulses than was the crude, simple transistor radio. Even the ARRL articles are now more than 20 years out-of-date.



True - However, the radios the ARRL tested are just about as sensitive as modern electronics gets. They most likely had JFET or MOSFET front ends, and some of them were microprocessor-controlled. We ain't talking vacuum tubes here! 



> I agree that the threat is greatly misunderstood and greatly exaggerated, but I still wouldn't want to be dependent on "civilization"s infrastructure and conveniences in the event of an effective EMP burst.



Oh, absolutely! I'm not dismissing the threat - I'm merely pointing out that many of the most commonly-cited EMP protective measures are misdirected and/or ill-advised.

AC power would almost certainly go away (probably for a long, long time), and so would phone/internet service. There could also be major damage to whatever devices happened to be connected to either of these utilities at the instant of the EMP event.

Thus, any time spent in addressing non-problems (such as building faraday cages for your flashlights! ) would be much better spent in installing protective devices on your AC power mains and phone lines, developing alternate sources for electrical power/heat/refrigeration/communications, etc. In other words, learn what the *REAL* EMP threats are, and prepare accordingly.


----------



## jnj1033 (Feb 18, 2007)

*Re: LED flashlights and E.M.P. vulnerability - thoughts?*



LowBat said:


> I'd like to have a device that produces directional EMP waves for those “considerate challenged” drivers that over-crank the bass on their car stereos.



I've often wished for that myself. If you ever build one, I'd like to be present for the first test.


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## tebore (Feb 19, 2007)

*Re: LED flashlights and E.M.P. vulnerability - thoughts?*



SEMIJim said:


> Not true. The most effective EMP burst is so far up that you would be unaffected by the direct blast.
> 
> ESD is not the same thing as EMP. EMP is electro-_magnetic_ in nature, not electro-_static_.
> 
> ...


 
EMPs causes huge surges. What do you think kills things a huge magnitic field that does nothing? They cause surges. I'm sure if those surges can damage your LED flashlights they'll fry your incan's little wire. The ESD diode can protect from the surge of energy depending on duration and magnitude. 

Again I'd like to a see a device that can cause an EMP as large as the ones produced by a nuke without using a nuke.


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## watt4 (Feb 19, 2007)

*Re: LED flashlights and E.M.P. vulnerability - thoughts?*

it's not emp, but it's a neat video

http://www.youtube.com/watch?v=2WFdyLAAzB0


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## Burgess (Feb 19, 2007)

*Re: LED flashlights and E.M.P. vulnerability - thoughts?*

Wow, that IS a cool video !


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## boosterboy (Feb 19, 2007)

*Re: LED flashlights and E.M.P. vulnerability - thoughts?*

Previously on Jericho....


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## z96Cobra (Feb 19, 2007)

*Re: LED flashlights and E.M.P. vulnerability - thoughts?*



watt4 said:


> it's not emp, but it's a neat video
> 
> http://www.youtube.com/watch?v=2WFdyLAAzB0



I've had that video (and another that I can't seem to locate) for a few years now, and am still amazed a the power (pun intended  ) of that "Jacobs Ladder". Another cool one I DL'd a long time ago is this transformer/substation explosion.

Roger


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## Brangdon (Feb 19, 2007)

*Re: LED flashlights and E.M.P. vulnerability - thoughts?*



AC_Doctor said:


> Just make sure that the butter cookie tin has a dedicated ground wire, or the tin will be worthless against the EMP...


Not so. You don't need a ground wire because we're not trying to dissapate a static charge or anything like that. Nor are we building a lightning rod. If anything, attaching a long earth wire would be counter-productive as it is more length. 

Generally things are at risk if they are very long or very thin. Very long means they get more current flowing in them, and very thin means that even a relatively low current generates enough heat to melt them. National grid power lines are at risk because they are long. We suspect that integrated circuits are at risk because they are thin - but they are also short, so who knows?



cage said:


> I think that the metal casing of the lamp might protect it from harm.


The LED is usually exposed through the lens. Roughly speaking, the pulse will have an associated frequency and hence wavelength, and will penetrate openings which are smaller than the wavelength.


----------



## Stereodude (Feb 19, 2007)

*Re: LED flashlights and E.M.P. vulnerability - thoughts?*

Generally speaking if battery powered electronics are turned off they're not vulnerable to EMP.


----------



## Stereodude (Feb 19, 2007)

*Re: LED flashlights and E.M.P. vulnerability - thoughts?*



LowBat said:


> Getting back on topic, I believe I read somewhere years ago that circuits could be protected from EMP waves. I just don't remember how the military accomplished this.


They are protected. Basically you dissipate all the electrical energy from the circuit before the EMP hits. Then you can power up the circuit again after the event.


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## Badbeams3 (Feb 19, 2007)

*Re: LED flashlights and E.M.P. vulnerability - thoughts?*

The old Mag lights would rule supreme.


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## k1rod (Feb 22, 2007)

*Re: LED flashlights and E.M.P. vulnerability - thoughts?*



tebore said:


> I'm sure if those surges can damage your LED flashlights they'll fry your incan's little wire. The ESD diode can protect from the surge of energy depending on duration and magnitude.


 
I don't think so. In an EMP event, the magnetic fields will create very large voltages but very low currents. These large voltages can punch a hole in anything with a PN junction such as an LED. A hotwire however will respond to the voltage potential by immediately pulling current. This current will severly limit the voltage potential that can be developed across the filament. 

What it boils down to is it takes very little power (V*I) to destroy a semiconductor. It takes a lot of power to melt a wire filament. An EMP event will at a local level, be a very high voltage, but very low power phenomena. Your hotwires will be just fine.


----------



## carbine15 (Feb 23, 2007)

*Re: LED flashlights and E.M.P. vulnerability - thoughts?*

don't they need a current flowing through a semiconductor to suffer damage from an EMP? I think all you have to do to save your lights is not have them on at the moment the emp hits.


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## cerenkov (Feb 23, 2007)

*Re: LED flashlights and E.M.P. vulnerability - thoughts?*

I am not positive about what I am going to post, but speculative EMP effects have been discussed on a physics forum I have been active on for several years.
Will a strong EMP burst fry our regulated LED lights if they are not 'on' at the time of the event? An EMP burst is not the same thing as an electrostatic discharge, but it acts in a somewhat similar way. As stated previously, if the wavelength of the local pulse is short enough (most likely it would be) to enter through your reflector, it could travel from the emitter wires to the electronics. The EMP pulse itself is the source of the voltage, no need for the switch to be on, as the surge is traveling a reverse route from emitter to electronics, not from a normal batteries>switch>electronics>emitter route. *IF* the pulse is capable of destroying electronics/LEDs, it may not matter if your light is on or off. That is reason I said it was somewhat similar to an electrostatic discharge. An electrostatic discharge will fry your computer's motherboad whether or not the computer is turned on. But ESD protection in your light may not save it from an EMP discharge.


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## rotncore (Feb 23, 2007)

*Re: LED flashlights and E.M.P. vulnerability - thoughts?*

Could you not just keep a few lights in a lead lined box? or one of those bags they use for film going through x-ray machines? Or a ESD bag that PC Cards and RAM come in? Or all three?


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## Jay R (Feb 23, 2007)

*Re: LED flashlights and E.M.P. vulnerability - thoughts?*

Isn't this a bit of a pointless topic ?? If you were close enough to the blast for the EMP to affect anything you have, then you would be close enough to have received a fatal dose of radiation, so who cares ??


Hey ! Here's a thought...
If you had an Orb NS then even if the protected cell and LED stopped working, with the extra dose of radiation the tritium locaters would probably now be bright enough to use instead ???


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## carbine15 (Feb 23, 2007)

*Re: LED flashlights and E.M.P. vulnerability - thoughts?*

most radiation in a mushroom cloud is only alpha particles. just don't breath them and you'll be fine.


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## k1rod (Feb 23, 2007)

*Re: LED flashlights and E.M.P. vulnerability - thoughts?*



Jay R said:


> Isn't this a bit of a pointless topic ?? If you were close enough to the blast for the EMP to affect anything you have, then you would be close enough to have received a fatal dose of radiation, so who cares ??
> 
> 
> This is completely untrue. The typical modeled EMP event is a high altitude air burst over Kansas which generates a destructive EMP from California to Maine. 95% of the people in the country would never know anything happened other than that their electronics stopped working.


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## mchlwise (Feb 23, 2007)

*Re: LED flashlights and E.M.P. vulnerability - thoughts?*

Thanks for all the replies and the information. As I said in my original post, there are a lot of aspects of the question that make it difficult to answer. I've been very interested in all of the viewpoints and responses. 



Jay R said:


> Isn't this a bit of a pointless topic ?? If you were close enough to the blast for the EMP to affect anything you have, then you would be close enough to have received a fatal dose of radiation, so who cares ??



As a number of people have stated, there are plenty of ways to survivably receive an EMP. My question with this thread kind of assumed (but didn't state) that the LED (and you) survived the nuclear explosion, and the fallout/radiation effects (if any) but were well within the range of the EMP.



rotncore said:


> Could you not just keep a few lights in a lead lined box? or one of those bags they use for film going through x-ray machines? Or a ESD bag that PC Cards and RAM come in? Or all three?



This is basically what I have started doing. A lead-lined box is significant overkill as all that is needed is a simple "Faraday cage" giving the pulse a path around the LED. I don't know how well film bags or ESD bags would serve this purpose. 

Here's my solution: An Ammo Box. I went down to the military surplus store, and got a small ammo box for less than $10 bucks. The ammo box is entirely made of steel. I put my flashlights in plastic zip-lock bags (the plastic serving as an insulator from the side of the box, closed it up, and they are now entirely surrounded by metal. 

The problem, and the purpose of the question, is that I don't want to be putting my frequently used lights into the ammo box all the time - it's just a pain. As of now, I've just got my "spares" and old rarely used lights in there. If there's a serious EMP event and all my LEDs get fried, my old never-used lights would be far better than nothing. 

What would be really nice would be to know that I don't have to worry about it.


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## Illum (Feb 23, 2007)

*Re: LED flashlights and E.M.P. vulnerability - thoughts?*



qip said:


> broken arrow was on tv today  and they nuked underground, all people above lived ok but the electronics still fried



remember the bikini atoll nuclear testing and how it fried several of California's computers?

I think if a sheet of aluminum foil is built into sheaths it may help a bit


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## sysadmn (Feb 23, 2007)

*Re: LED flashlights and E.M.P. vulnerability - thoughts?*



r0b0r said:


> If you're a sociopath, a 1kW+ magnetron (hooray for microwave ovens!) with a waveguide might do the trick...
> 
> I wonder how well those things perform over a ~10m range?



Google "homemade herf" for a lot of amusing speculation. Automakers design electronics for robustness to EMI. You might overload the radio's front end, but it's not like you're going to smoke his WalMart 350 Watts!!!!! Mega Base Boost!!! power amp. 

Unfortunately.


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## Jay R (Feb 23, 2007)

*Re: LED flashlights and E.M.P. vulnerability - thoughts?*

How I understand it is that the EMP is converted into current by long wires such as mains, telephone, wound in an alternator, etc.. Whatever current is sucked up by the 1cm wire from the battery to the LED certainly won't bother an LED or bulb that's used to having 1amp pushed through it. Direct drive lights should therefore be fine.
If it's got a chip, well... If it was in a laptop and therefore connected to a stretched out total of perhaps 20, 30 even 40 feet or more of circuit board and wires, it may fry the chip, but a chip connected to a 1cm diameter board and a few mm of wires... probably not.

Assuming it did survive, it had better not be a rechargeable light, where are you going to plug it in ???  

How about a candle and some matches....


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## k1rod (Feb 23, 2007)

*Re: LED flashlights and E.M.P. vulnerability - thoughts?*



Jay R said:


> Whatever current is sucked up by the 1cm wire from the battery to the LED certainly won't bother an LED or bulb that's used to having 1amp pushed through it. Direct drive lights should therefore be fine.


 
It may be used to having an amp through it but it is not used to having 50kV across it. It takes miniscule current to poke a hole in a PN junction, just very high voltage. It is certainly true that anything that has an "antenna" type structure on it is going to be more vulnerable but I don't think an LED based light is, even direct drive, is invulnerable. I see the military spending a lot of money to EMP harden a lot of equipment that has no long wire on it. Now if there were metalic caps that covered the lens and switch assembly and had electrical contact to the main body of the light, the whole thing would look like a faraday cage and may be invulerable.


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## Mark H. (Feb 23, 2007)

*Re: LED flashlights and E.M.P. vulnerability - thoughts?*

Mac has probably already designed a flashlight that will utilize EMP to create a 5 billion candlepower burst. The included lanyard will contain 25 yards of braided copper wire. I predict it will have terrific throw, but doing a proper beam test may be difficult.


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## Stereodude (Feb 23, 2007)

*Re: LED flashlights and E.M.P. vulnerability - thoughts?*



k1rod said:


> I see the military spending a lot of money to EMP harden a lot of equipment that has no long wire on it.


I have no idea what you're talking about. At my last job I designed circuits for miliary use that would withstand EMP. There isn't much magic in the design. They key was to make sure you had all the energy out of the boards prior to the pulse and they would withstand the EMP. Other types of radiation were much harder to deal with because it would change the gain of op amps and other semiconductors used in analog circuits.


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## mchlwise (Feb 23, 2007)

*Re: LED flashlights and E.M.P. vulnerability - thoughts?*



Stereodude said:


> I have no idea what you're talking about. At my last job I designed circuits for miliary use that would withstand EMP. There isn't much magic in the design. They key was to make sure you had all the energy out of the boards prior to the pulse and they would withstand the EMP. Other types of radiation were much harder to deal with because it would change the gain of op amps and other semiconductors used in analog circuits.



So what you're saying is

Generally speaking if battery powered electronics are turned off they're not vulnerable to EMP.

:shrug:


----------



## k1rod (Feb 23, 2007)

*Re: LED flashlights and E.M.P. vulnerability - thoughts?*



mchlwise said:


> So what you're saying is
> 
> Generally speaking if battery powered electronics are turned off they're not vulnerable to EMP.
> 
> :shrug:


 
You certainly can proceed according to that theory however I would also suggest you lay in a supply of candles. :laughing:


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## carbine15 (Feb 23, 2007)

*Re: LED flashlights and E.M.P. vulnerability - thoughts?*



k1rod said:


> You certainly can proceed according to that theory however I would also suggest you lay in a supply of candles. :laughing:


I'm just going by what I was told in the army. They told us to turn off the SinGARS radios and pull the hub battery if there was a nuke so that we could turn them on an a few minutes and have communications. "turn off all electronic devices until the EMP has discipated. Don your protective masks and get the hell out of the fallout (drive downwind and away from the blast.)
Normaly we wouldn't have the warning to enact these procedures but the nukes were likely to be ours at the time in retaliation to any biological or chemical threat Saddam wanted to use. Saber rattling in Kuwait after the first gulf war.


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## Stereodude (Feb 23, 2007)

*Re: LED flashlights and E.M.P. vulnerability - thoughts?*



mchlwise said:


> So what you're saying is
> 
> Generally speaking if battery powered electronics are turned off they're not vulnerable to EMP.


That would tend to be my belief, but I can't say for sure. I suspect a large portion of the EMP information is not entirely accurate. What is being said is somewhat absurd. Fairly sophisticated electronics can withstand power surges caused by lightning as long as their turned off. An EMP isn't going to generate the level of voltage that lightning has. It therefore seems logical to say that an EMP will probably not damage a large percentage of unpowered electronics.


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## SEMIJim (Feb 23, 2007)

*Re: LED flashlights and E.M.P. vulnerability - thoughts?*



Stereodude said:


> Fairly sophisticated electronics can withstand power surges caused by lightning as long as their turned off.


Yeah, well, that depends on the intensity of the lightning bolt, its proximity to the equipment, the point(s) to which the surge is induced, and a variety of other factors. I guarantee you, for example, that if the surge is induced via a connection other than the power connection, whether or not the equipment is powered-up at the time won't make a damn bit of difference with a close hit.



Stereodude said:


> An EMP isn't going to generate the level of voltage that lightning has.


Unwarranted assumption. It depends on a multitude of factors. For example: I bet an EMP burst directly overhead will generate more energy in your electronics than the largest of lightning hits five miles away.



Stereodude said:


> It therefore seems logical to say that an EMP will probably not damage a large percentage of unpowered electronics.


Unwarranted assumption, for the reasons cited previously.


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## Stereodude (Feb 23, 2007)

*Re: LED flashlights and E.M.P. vulnerability - thoughts?*

Apparently the military doesn't know what they're talking about then...


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## Skibane (Feb 23, 2007)

*Re: LED flashlights and E.M.P. vulnerability - thoughts?*



SEMIJim said:


> Unwarranted assumption. It depends on a multitude of factors. For example: I bet an EMP burst directly overhead will generate more energy in your electronics than the largest of lightning hits five miles away.



Ah, but your *bet* is based on another assumption! 

Again, as previously posted, the strength of the electrical spike induced in 'your electronics' depends on how much antenna, power line, phone line, etc. it has connected to it. In the absence of any long conductors, the amount of EM pulse intercepted by the conductors is insignificant, and thus damage to the device is unlikely - no matter how close the detonation is.

The ARRL tests previously posted in this thread are "required reading" in this regard. There was no speculation in these tests - They actually subjected various devices to EMP, and noted the results: Short conductors = no damage.


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## k1rod (Feb 23, 2007)

*Re: LED flashlights and E.M.P. vulnerability - thoughts?*



Stereodude said:


> Apparently the military doesn't know what they're talking about then...


 
Apparently, you think that the small cross section of work that you perhaps got to perform for the some aspect of the military was representative of their ideas on this subject as a whole. I worked for 15 years in a military research center. I can tell you, you are wrong.


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## cerenkov (Feb 24, 2007)

*Re: LED flashlights and E.M.P. vulnerability - thoughts?*



Skibane said:


> Ah, but your *bet* is based on another assumption!
> 
> 
> 
> ...


Skibane, I think you are confusing the effects of the secondary magnetohydromagnetic signal (MHD-EMP) with the primary EMP burst, the HEMP signal. The MHD-EMP burst (also called the 'heave' signal) *IS* predicted to only effect electronics connected to 'long-lines' or large antennas. However, the very first, very short duration HEMP burst is expected to disable smaller unshielded electronic equipment, such as the computer systems and electronic components in our automobiles. Shielding such electronics from an EMP burst is very difficult, the EMP can enter through the slightest holes and cracks in any enclosure, such as where wires exit through the enclosure. Predicting exactly what could be effected is still almost impossible, but isolation from 'long-lines' or large antennas does not provide protection from the initial EMP burst, only the latter MHD-EMP signal that comes from the distrubance of Earth's magnetic field lines.


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## Skibane (Feb 24, 2007)

*Re: LED flashlights and E.M.P. vulnerability - thoughts?*



cerenkov said:


> Skibane, I think you are confusing the effects of the secondary magnetohydromagnetic signal (MHD-EMP) with the primary EMP burst, the HEMP signal.



Nope, I am referring to the HEMP pulse, and am neglecting the effects of the MHD-EM pulse, since the latter does - as you correctly state - only affect VERY long conductors (transmission lines, VLF antennas for submarine communications, etc.).

HEMP is generally regarded as being the most significant threat to typical consumer electrical and electronic devices, and thus was the subject of the ARRL tests - not MHD-EM, and not SGEMG (System-Generated EMP). Again, if you read the ARRL overview and test results, this is immediately apparent.


----------



## carbine15 (Feb 24, 2007)

*Re: LED flashlights and E.M.P. vulnerability - thoughts?*

so turning off any electronics will boost the potential for that device to survive an emp (not directly under a blast)


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## cerenkov (Feb 24, 2007)

*Re: LED flashlights and E.M.P. vulnerability - thoughts?*

Sorry, but if your flashlight contains a circuit board it is venerable to EMP pulses. The links that Skibane gave are from a 1987 article by the amature radio association, not from experts in the field. 
There are many ways to generate EMP-type pulses, high altitude nuclear explosions being only one of them. New RF weapons have been developed that operate on this same principle that was discovered in 1962. Here is a link and cut & paste to a report that was given to the U.S. House in 1998.
http://www.house.gov/jec/hearings/radio/merritt.htm




> "…construction of effective explosively-driven Flux Compression Generator devices is entirely feasible for established military powers such as Russia, China, France, Germany, et cetera,…"
> "There is no confirmed evidence of employment of such a device to date … available in open sources".
> "Modern Metal Oxide Semiconductor technology, on which most of our critical national infrastructures depend, unless deliberately protected or "hardened", is extremely vulnerable to even low–power electromagnetic pulses..."
> "…it is well understood that the US is disproportionately more vulnerable to RF attack than are less developed nations."






> *Electrically Driven Devices: The electrically driven (non-explosive) devices require an external power supply and energy storage system, which often leads to larger and less self-contained systems than can be produced by explosive-driven approaches. However, two recent technologies that minimize this limitation are the solid state pulsers developed at Ioffe Physico-Technical Institute in St. Petersburg and the RADAN system. These devices are quite compact and can be powered by small hand-carried energy sources.
> 
> Pulsers developed at Ioffe Physico-Technical Institute are based upon very fast (nanosecond and picosecond) solid state "on" and "off" switches developed by Prof. Igor Grekhov and Dr. Alexi Kardo-Syssoev. These switches have recently been used to generate 10 nanosecond, 10 KHz pulses for a prototype ground penetrating sensor that is now being used commercially in St. Petersburg (Figure 2). This 10 kg portable sensor is said to be used routinely to image to depths of 200 meters with an accuracy of 1% of the depth and it is claimed to be able to image down to 1000 meters with slightly lower resolution13. Jammers based upon these switches can be made small enough to fit into a briefcase. A recent version is said to weigh 6.5 kg and to deliver fields of 30 kV per meter at 5 meters. This is comparable to high-altitude EMP (HEMP) field strength. An optimized version is said to deliver 100 kV per meter at 5 meters14, 15 and the pulse width and repetition rate can be tuned to have the maximum effect on the intended target. RADAN16 (Figure 3) is a compact high-current electron accelerator that is a little smaller than an attaché case and weighs about 8 kg with its rechargeable 12 volt battery power supply, but not including its antenna. RADAN can be used to stimulate several outputs including lasers, x-rays, wide band RF and high power microwaves that allow RADAN to be used as a jammer. RADAN output parameters are: total output power > 5 MW; repetition rate up to 1 kilohertz; pulse width about 2 nanoseconds; and output pulse bandwidth from 1 MHz to 5 GHz. A directional antenna has been developed and the developer has proposed that RADAN could be used to stop car engines and to destroy the electronic arming and firing circuits of bombs. Limited testing of RADAN has been conducted in the U.S. and it was found to affect calculators and electronic watches.
> 
> ...


----------



## SEMIJim (Feb 24, 2007)

*Re: LED flashlights and E.M.P. vulnerability - thoughts?*

Thanks for the cites, cerenkov. I was too damn lazy to hunt that stuff down.

Like I believe I mentioned earlier: I saw a not-so-portable (at the time) EMP-generating device demonstrated on some-or-another TV program several years ago. It was obviously only a question of time until they got the size issues resolved.


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## Led-Ed (Feb 24, 2007)

*Re: LED flashlights and E.M.P. vulnerability - thoughts?*

Do a search on google for the term "E-Bomb" 
Even if your flashlight still works , not much other electronic stuff will .


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## Skibane (Feb 24, 2007)

*Re: LED flashlights and E.M.P. vulnerability - thoughts?*



cerenkov said:


> Sorry, but if your flashlight contains a circuit board it is venerable to EMP pulses. The links that Skibane gave are from a 1987 article by the amature radio association, not from experts in the field.



If you read the report in the ARRL link I provided, you'll notice that it was condensed from National Communications System TIB # 85-10, and was written by the same Office of Technology & Standards staffer who authored the original report.

The link you cited speculates on techniques that may be theoretically capable of generating EMP over relatively short distances - "RF bombs" directed at specific, high-value targets (typically military) - rather than continent-spanning HEMP bursts (the only kind of EMP that the average citizen is likely to encounter).

Also, your link makes no mention of the vulnerability of flashlight circuit boards to EM pulses...If you have some *actual test results* to back up your assertion - *actual tests* that contradict the *actual tests* I've cited, I'm sure we'd all like to see them.


----------



## Templar223 (Feb 24, 2007)

*Re: LED flashlights and E.M.P. vulnerability - thoughts?*



tebore said:


> It's been discussed that an EMP strong enough to damage your flashlight would be the least of your concerns. Strong EMPs are usually caused by Nukes which would turn you into red vapor.



No. Mr. Tebore. While nukes are the best way I'm aware of to cause strong EMPs, they are best done in the upper atmosphere where there is little air to carry away the energy of the blast. Absent atmosphere to mechanically distribute that energy, you get electro-magnetic energy. Hence, EMP.

Conceivably you could have a ultra-high atmospheric burst and not even realize it if you didn't see the flash. There would be no sound as there is no atmosphere to carry the sound waves.

Only if you ware very close to a ground blast would you detect an EMP pulse, but as you said, you would be vaporized.



tebore said:


> EMPs would kill incans as well because a surge would break the filament.



Where do you come up with this stuff? You will get no significant surge in a flashlight, unless it's connected to the power grid. Even then, I'd be skeptical about a blown bulb unless the unit was "on" when the pulse hit (while it was plugged in!).




tebore said:


> Again if an EMP struck, a non working flashlight would be the least of your concerns.



Aside from whether or not your flashlights work, you and I are in complete agreement on this point.

The best way to store your unused electronics, be they radios or whatever, is to store them in a metal cabinet to minimize any risk, significant or not, of EMP zapping them if and when Iran, Chiana or N. Korea decide to get the most "bang" from one or two nukes against the US.

John


----------



## zpaulg (Jun 13, 2007)

*Re: LED flashlights and E.M.P. vulnerability - thoughts?*

I could be totally wrong but I believe that only "active" electrical items would be damaged by an E.M.P.

In other words if your flashlight was off at the time of the pulse it would be unaffected!

If there is a nuclear blast and we both happen to survive feel free to slag me off on the forums if I'm wrong.......since the forums will last foreverrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrr!!!!!


----------



## Handlobraesing (Jun 13, 2007)

*Re: LED flashlights and E.M.P. vulnerability - thoughts?*



mchlwise said:


> My question is: *how vulnerable are LEDs and LED flashlights to E.M.P.? *


Why don't you microwave your L1D-CE while it's on and let us know how it turns out?


----------



## mchlwise (Jun 14, 2007)

*Re: LED flashlights and E.M.P. vulnerability - thoughts?*



Handlobraesing said:


> Why don't you microwave your L1D-CE while it's on and let us know how it turns out?



If you don't have anything valuable to contribute, why don't you refrain from posting? 

edit: ...instead of coming in here with more of your Fenix-bashing. 

:shakehead


----------



## ltiu (Jul 13, 2007)

*LED battlefield survivability*

Curiosity:

I think LED is a silicon chip based (semi-conductor) electronic part.

Does this mean if an EM bomb or a nuke goes off, LED lights go kaput?

Could this be the reason a lot of military type lights are still using incans?


----------



## Illum (Jul 14, 2007)

*Re: LED battlefield survivability*

if LEDs were exposed to EMP yeah it basically goes kaput from the internal copper wirings vaporizing and blowing out the resin capsule...but I don't think thats the reason they're not used as extensively on the battlefield as the xenon.

I think it has more to do with color rendition


----------



## meuge (Jul 14, 2007)

*Re: LED battlefield survivability*

LED circuits are fairly high-current, and can handle a reasonably large current range, and the emitters are likely to be able to withstand a fairly large current spike. Furthermore, they are somewhat shielded from direct radiation by the metal casing of the different flashlights. 

I would think that LED lights stand a decent chance of still functioning after an EMP. That being said, there is only 1 condition under which it would matter - to produce a strong EMP without the direct destruction by the accompanying nuclear blast, the detonation would have to occur in the upper ionosphere (~200km). 

To think that any nation in the world would launch a nuclear weapon at the U.S. via a ballistic missile is kind of silly. The inevitable response would reduce any such nation to a glowing hole in the earth. 

The only likely scenario for a (god forbid) nuclear attack on american soil, is one of a low-yield ground-detonated device. In this case, given the line-of-sight nature of the EMP, and the relatively low fraction of the energy released as EMP, the only way for the EMP to be strong, is to be so close to the detonation site, that EMP would be the least of your problems. 

Hope that answers your question.


----------



## Wolfhound 9K (Jul 14, 2007)

*Re: LED battlefield survivability*

I believe that the reason incans are still the primary light of choice on the battlefield today is because of their IR compatibility


----------



## Derek Dean (Jul 14, 2007)

*Re: LED battlefield survivability*

Wow, 2 first posters in a row. Welcome to CPF meuge and Wolfhound 9K! All this talk of a nuclear (how DO you pronounce that) blast is making me hungry for a late night snack. Time to 'nuke' a hot pocket.


----------



## LightJaguar (Jul 14, 2007)

*Re: LED battlefield survivability*

I agree with Meuge. If you are close enough for a nuclear explosion to affect your lights then you probably have a lot of other things to worry about. Like how long you have left to live if you even survive. 
I think that flashaholics tend to overanalize things way too much. The reason why the military uses incan is actually very simple. They are way cheaper then any other light. The way things are contracted usually means that the military ends up paying twice as much for just about everything.


----------



## BBL (Jul 14, 2007)

*Re: LED battlefield survivability*



meuge said:


> The inevitable response would reduce any such nation to a glowing hole in the earth.



genuine american...


----------



## DM51 (Jul 14, 2007)

*Re: LED battlefield survivability*

LOL, if a nuke goes off, you won't have to worry about the LED working - there will be plenty of ambient light as everything around you will be a tasteful GITD green color, including the LED's phosphor and maybe even your own eyeballs.


----------



## GregWormald (Jul 14, 2007)

*Re: LED battlefield survivability*

Nuclear--new clear NOT nuke u ler.
Greg


----------



## Derek Dean (Jul 14, 2007)

*Re: LED battlefield survivability*



GregWormald said:


> Nuclear--new clear NOT nuke u ler.
> Greg


Ahhhhhh....... thanks Greg..... being a pure bred Okie... I can sometimes get my words a might flobuglated.... and it always bothered me that I couldn't understand how NOT to say it. 

Now, if I could just stop myself from saying "you'all"..... I might not get pegged so quickly as being from the midwest (not that that's a bad thing ).


----------



## NA8 (Jul 14, 2007)

*Re: LED battlefield survivability*



meuge said:


> To think that any nation in the world would launch a nuclear weapon at the U.S. via a ballistic missile is kind of silly. The inevitable response would reduce any such nation to a glowing hole in the earth.



Military stuff always makes me a bit uneasy. A friend of mine was reading a book on the history of great military blunders and couldn't finish the book it was so depressing.


----------



## TorchBoy (Jul 14, 2007)

*Re: LED battlefield survivability*



GregWormald said:


> Nuclear--new clear NOT nuke u ler.
> Greg


Now, is that nyu'-clee-arr or nu-cleh?


----------



## GregY (Jul 14, 2007)

*Re: LED battlefield survivability*



NA8 said:


> Military stuff always makes me a bit uneasy. A friend of mine was reading a book on the history of great military blunders and couldn't finish the book it was so depressing.


 
I don't know, it's just like any other human activity. More often than not, the winning side is usually the side that screws up the least.


----------



## GregY (Jul 14, 2007)

*Re: LED battlefield survivability*



BBL said:


> genuine american...


 
Lighten up, Francis.

Change 'U.S.' to 'France' in the original post you're quoting and the rest of it is still the same. Launching a (painfully non-deniable) ballistic missile at a nuclear power is not a good idea. I'm good with that. It helps keep the rowdies in line.


----------



## Illum (Jul 14, 2007)

*Re: LED battlefield survivability*



meuge said:


> To think that any nation in the world would launch a nuclear weapon at the U.S. via a ballistic missile is kind of silly. The inevitable response would reduce any such nation to a glowing hole in the earth.



do some research on Korean mid-range ballistic missile testing...its not silly, it could very well happen and we might be under another crisis like the cold war. Its silly because the land that the opposing nation have liberated cannot be used for another thousand years



LightJaguar said:


> I think that flashaholics tend to overanalize things way too much. The reason why the military uses incan is actually very simple. They are way cheaper then any other light.



well, aside from IR compatibility if you look at performance from the "runtime perspective" if LEDs were retrofitted for military gear [visible for visible, infrared for infrared] imagine the savings in batteries

cheaper? you think weapon lights are cheaper? refer to the surefire page...granted surefire sells weapon lights cheaper than its consumer line but I don't see how you would justify a 3 digit price as cheap:thinking:


----------



## gorn (Jul 14, 2007)

*Re: LED battlefield survivability*

My Son is an Airborne Scout Sniper. He only uses LED based lights. His main light is a Typhoon. He has a surefire weapons light on his M-4, I forget which model.

He has had no problem (other than losing a couple of lights while crossing canals) with them. After seeing his lights and how well they work the rest of the company is now replacing the incans they have with LEDs.


----------



## txmatt (Jul 14, 2007)

*Re: LED battlefield survivability*

Uh oh, I can see it now. We aleady have a forward/normal clickie worshipping subset here at CPF, who may get plucked from their desk job to have to clear a room of terrorists or signal someone after a plane crash or some other scenario only a forward clickie can accomplish. Now we'll have folks claiming they need light X or Y because it will survive a nuclear or EM weapon attack.


----------



## Daniel_sk (Jul 14, 2007)

*Re: LED battlefield survivability*



txmatt said:


> Uh oh, I can see it now. We aleady have a forward/normal clickie worshipping subset here at CPF, who may get plucked from their desk job to have to clear a room of terrorists or signal someone after a plane crash or some other scenario only a forward clickie can accomplish. Now we'll have folks claiming they need light X or Y because it will survive a nuclear or EM weapon attack.


ha ha ha, you nailed it.


----------



## NA8 (Jul 14, 2007)

*Re: LED battlefield survivability*

The History Channel had a show on the Sun recently. They were hot and bothered about a huge solar mass ejection scoring a direct hit on Earth's magnetic field. They said it happened once already, before widespread use of transistors. They're afraid it could be the same as an EMP on a global scale.


----------



## Confederate (Jul 14, 2007)

*Re: LED battlefield survivability*

You can always buy an ammo case and store your flashlights and PDA in it, making sure that they're insulated from direct contact with the steel sides or tops. This also will protect a PDA or cell phone.

Presently, one of the fears by the U.S. is that Iran or some other country would launch a nuclear weapon over the U.S. land mass in an attempt to knock out the computers and drives that keep the economy going. If launched from a small boat and detonated high enough and inland enough, it could indeed fry your cars, computers, flashlights, PDAs, cell phones, as well as just about everything else we rely on for comfort (except firearms, thank goodness). In such a case it would be difficult if not impossible to tell which country had done it. You'd have the equivilant of New Orleans all over a large section of the country.

It's fairly cheap to protect these things, but unfortunately, people don't learn from history. The military hardens its electronics. For the rest of us, though, we'll be in trouble.


----------



## wintermute (Jul 15, 2007)

*Re: LED battlefield survivability*



Confederate said:


> You can always buy an ammo case and store your flashlights and PDA in it, making sure that they're insulated from direct contact with the steel sides or tops. This also will protect a PDA or cell phone.
> 
> Presently, one of the fears by the U.S. is that Iran or some other country would launch a nuclear weapon over the U.S. land mass in an attempt to knock out the computers and drives that keep the economy going. If launched from a small boat and detonated high enough and inland enough, it could indeed fry your cars, computers, flashlights, PDAs, cell phones, as well as just about everything else we rely on for comfort (except firearms, thank goodness). In such a case it would be difficult if not impossible to tell which country had done it. You'd have the equivilant of New Orleans all over a large section of the country.
> 
> It's fairly cheap to protect these things, but unfortunately, people don't learn from history. The military hardens its electronics. For the rest of us, though, we'll be in trouble.



Way to scare the crap outta everyone early Sundayt morning. 

But yeah, I've read up on these kind of scenarios myself. From all of the information I have read over the last decade or so, I think we're at a much greater risk of a dirty bomb attack in a large city then any type of EMP/nuclear attack.


----------



## curtis22 (Jul 15, 2007)

*Re: LED battlefield survivability*



Confederate said:


> You can always buy an ammo case and store your flashlights and PDA in it, making sure that they're insulated from direct contact with the steel sides or tops. This also will protect a PDA or cell phone.



I don't think the cell phone system would survive an EMP attack.


----------



## yellow (Jul 15, 2007)

are the effects of EMP (or EMP itself) something noticed in real life, or is this a theoretical concept?
I seem not to get serious infos 
:thinking:

and should not most of our precious gear already be safe?
My lights feature an aluminium housing + reflector, my computer has the normal metal housing, ...
(sure, I will get mad, when the internet is off for 3 days, but as long as the power grid runs, so does most of our western life, at least on the short term?
right? wrong?

as above examples show, the genereal public seems to notice how good led lights are for normal power chores, and with every person owning an average quality light, even more will get hooked


----------



## DM51 (Jul 15, 2007)

*Re: LED battlefield survivability*

Power would be one of the first things to go out.


----------



## curtis22 (Jul 15, 2007)

*Re: LED battlefield survivability*



yellow said:


> are the effects of EMP (or EMP itself) something noticed in real life, or is this a theoretical concept?
> I seem not to get serious infos



http://en.wikipedia.org/wiki/Electromagnetic_pulse


----------



## Confederate (Jul 15, 2007)

*Re: LED battlefield survivability*



yellow said:


> are the effects of EMP (or EMP itself) something noticed in real life, or is this a theoretical concept?


No, this is not a theoretical concept. I used to work for the Navy, and I've talked to many electrical engineers regarding this problem. In the event of a war, U.S. weapons systems would have to keep working in order to launch an effective counterstrike. While part of the government tells us not to worry, another part is fortifying its own systems. 

A protected Faraday box will protect your devices if they're in the box when the attack comes. Notebook computers are not protected and I don't know of any retailer that protects their systems; nor do I know of any car company that is hardening its vehicles. In fact, they're adding even more electronics each year. If such an attack comes, the guy who owns an old '57 Chevy will be doing quite well -- at least until he runs out of gas.

In such a scenario, having good flashlights and batteries would be imperative. The 123A batteries have a good shelf life and they can be had at a good price. So adding to your stock every three or four years would be prudent. It also would pay to make a list of things you might need in such an emergency. Produce might come to stop, at least for awhile, as trucks will not work, inventorying and billing will have to be done by hand and so forth.


----------



## meuge (Jul 15, 2007)

*Re: LED battlefield survivability*



Confederate said:


> Presently, one of the fears by the U.S. is that Iran or some other country would launch a nuclear weapon over the U.S. land mass in an attempt to knock out the computers and drives that keep the economy going. If launched from a small boat and detonated high enough and inland enough, it could indeed fry your cars, computers, flashlights, PDAs, cell phones, as well as just about everything else we rely on for comfort (except firearms, thank goodness). In such a case it would be difficult if not impossible to tell which country had done it. You'd have the equivilant of New Orleans all over a large section of the country.



To have a pulse sufficient to affect a "large section of the country", you'd need a high-yield thermonuclear weapon (in the ten megaton range), detonated at very high altitude. If you think that anyone other than U.S. and Russia has such a weapon, you've got to be dreaming. 

The amount of circumstances and technologies that would have to come together, in order for someone to launch such an attack, are so vast that it makes such a circumstance unlikely, except for a true first-strike scenario. 

But in the latter case, the potential enemy is unlikely to use one of their precious high yield warheads to try and disrupt our economy. It's simply madness that someone would risk annihilation to fry our easily-replaceable (in a long-term sense) electronics. If a terrorist state were to gain possession of an appropriate missile, with a high-yield warhead, they wouldn't detonate it 200km over the east coast, they'd detonate 2km over a city on the east coast.


----------



## meuge (Jul 15, 2007)

*Re: LED battlefield survivability*



Derek Dean said:


> Wow, 2 first posters in a row. Welcome to CPF meuge and Wolfhound 9K! All this talk of a nuclear (how DO you pronounce that) blast is making me hungry for a late night snack. Time to 'nuke' a hot pocket.



Thank you... it's a pleasure to browse this forum.


----------



## ltiu (Jul 17, 2007)

*Re: LED battlefield survivability*



Derek Dean said:


> Wow, 2 first posters in a row. Welcome to CPF meuge and Wolfhound 9K! All this talk of a nuclear (how DO you pronounce that) blast is making me hungry for a late night snack. Time to 'nuke' a hot pocket.



Hmmm, talking about nuking, has anyone tried nuking an LED in the microwave? Just wondering.


----------



## Dinan (Jul 17, 2007)

*Re: LED battlefield survivability*



ltiu said:


> Hmmm, talking about nuking, has anyone tried nuking an LED in the microwave? Just wondering.



My friend nukes his old cellphones in the microwave after he gets new ones. He claims it's to make sure no one can ever get the info off of it lol


----------



## TorchBoy (Jul 17, 2007)

*Re: LED battlefield survivability*



Dinan said:


> My friend nukes his old cellphones in the microwave after he gets new ones.


How many toxic gases would _that_ release?


----------



## joema (Jul 18, 2007)

*Re: LED battlefield survivability*

In case anybody is interested, this was discussed in detail in this thread: https://www.candlepowerforums.com/threads/105568&highlight=SCUD-D

A few points: 

There have been numerous nuclear explosions at high altitude and in space. From these we know a high altitude detonation will NOT cause blast or radiation damage to people on the ground, yet can produce damaging EMP. http://en.wikipedia.org/wiki/High_altitude_nuclear_explosion

In general an EMP attack would require a fusion (ie, hydrogen) bomb, not a simple fission bomb. Fission bombs of the required yield would be too heavy and require far too much material. Fusion bombs are much more complicated to make and maintain.

Whether an LED flashlight would be affected is hard to state definitively. A high altitude nuclear detonation can impose 50,000 volts per meter to conductors on the ground.

However there are many variables: detonation altitude, yield, distance, conductor (antenna) length, degree of shielding, susceptibility of the electronics to damage, and type of EMP waveform (there are several). 

Whether the LED flashlight has a plastic or metal body is probably a factor. Also whether it's a simple direct-drive flashlight, a regulated light, or a microprocessor-controlled light could make a difference.

http://www.fas.org/nuke/intro/nuke/emp.htm
http://www.fas.org/nuke/intro/nuke/emp/toc.htm

From a tactical standpoint, an EMP attack seems unlikely. As already stated, it's likely no small power would waste a nuke on EMP. Given a limited arsenal, they are too valuable as a direct weapon to squander on EMP. If delivered by missile, the trajectory also gives an unmistakable "return address" to the launcher, which would have dire consequences.

Of course a larger power like Russia or the U.S. could use dedicated EMP nukes. The most effective way would NOT be an ICBM launch, but concealing several in low orbital satellites and doing a coordinated surprise detonation as a disruptive prelude to a full-scale nuclear attack. In that case there would be major EMP damage. However whether flashlights worked in the 20 min interval between the EMP detonation and full-scale attack would probably be immaterial for most people.


----------



## LightJaguar (Jul 31, 2007)

*Re: LED battlefield survivability*

well, aside from IR compatibility if you look at performance from the "runtime perspective" if LEDs were retrofitted for military gear [visible for visible, infrared for infrared] imagine the savings in batteries

cheaper? you think weapon lights are cheaper? refer to the surefire page...granted surefire sells weapon lights cheaper than its consumer line but I don't see how you would justify a 3 digit price as cheap:thinking:[/quote]

Well it seems like SureFire marketing has gotten the better of you. As a fomer U.S Armed Forces personnel I can assure you that not everyone in the military runs around with SureFires. As a matter of fact I never saw a SureFire while in the Military. I worked along with Marines, the Army plus Navy personnel. The best light that I recall seeing was some Brinkman flashlight. The incans that I was refering to are the green ones that are common in the military and the cheap 2 D plastic ones. If my best buddy (a US Marine) deploys again I will supply him with some quality lights and batteries.


----------



## peacefuljeffrey (Jul 31, 2007)

*Re: LED battlefield survivability*



meuge said:


> To think that any nation in the world would launch a nuclear weapon at the U.S. via a ballistic missile is kind of silly. The inevitable response would reduce any such nation to a glowing hole in the earth.


 

As much as I would _like_ to think that's what our reaction would be, something tells me that we have enough pansies in high places that we'd be admonished, "Now- now don't go off all angry and do something you might regret!"

We'd have people telling us that the ones who did the attack on us don't represent _all_ of their kind, so it's not fair to kill innocents to get at them, or to judge their group as a whole based on the actions of "a few". :sick2:

I think, sadly, that we would not be able to count on the "unleash hell" type of response from the defanged U.S. military. :sigh: Not with the mealy-mouthed pansies we have in power today. It is often said that if it were up to the people who run the show nowadays, we wouldn't have had a prayer of winning WWII. I believe them.


----------



## SheikRattleEnroll (Aug 1, 2007)

*Re: LED battlefield survivability*

I don't think Iraq is a result of people saying "don't go off all angry and do something you might regret", it's exactly the opposite. Someone said "We have no proof these people did anything to us, but let's attack them and start a second war, split our military in half, then if we win let's try and build a new country out of the rubble with the taxes our people pay." Osama Bin Laden said the goal of his strategy was to bankrupt America. We've played right into his hands so far with that. And people want to start more wars in the middle east and bankrupt our country further! They're so afraid of a handful of people that they're willing to destroy our entire nation to get them.

The people in power had plenty of desire to "unleash hell" and that's the problem. We defeated Germany and Japan quicker than a handful of untrained uneducated unequipped Iraqis. Plainly spoken, we acted without thinking and developing a viable strategy.

As far as your views on killing innocent people, the war on terror is a war against a tactic, namely that of terrorism, which is the killing of innocent people to achieve a military objective. Is that what you want us to be, terrorists? And if everyone thinks it's ok to judge a religious group based on the actions of a few this earth will be reduced to a lake of fire in no time. 

I agree we wouldn't have won WWII if the people in power now were in power then. We'd be fighting a never ending war of attrition against an abstract ideal instead of concentrating on the real threat of Germany and Japan. 



peacefuljeffrey said:


> As much as I would _like_ to think that's what our reaction would be, something tells me that we have enough pansies in high places that we'd be admonished, "Now- now don't go off all angry and do something you might regret!"
> 
> We'd have people telling us that the ones who did the attack on us don't represent _all_ of their kind, so it's not fair to kill innocents to get at them, or to judge their group as a whole based on the actions of "a few". :sick2:
> 
> I think, sadly, that we would not be able to count on the "unleash hell" type of response from the defanged U.S. military. :sigh: Not with the mealy-mouthed pansies we have in power today. It is often said that if it were up to the people who run the show nowadays, we wouldn't have had a prayer of winning WWII. I believe them.


----------



## DM51 (Aug 1, 2007)

*Re: LED battlefield survivability*



SheikRattleEnroll said:


> I don't think Iraq zzzzz don't go off all angry zzzzzzzzzzz destroy our entire nation zzzzzzzzzzzz people in power zzzzzzzzzzz "unleash hell" zzzzzz that's the problem zzzzzzzzzzzz Germany and Japan zzzzzzzzzzzzz killing innocent people zzzzzzzzzzzzzzz earth will be reduced to a lake of fire zzzzzzzzzzzzz never ending war of attrition zzz abstract ideal zzzzzzz threat of Germany and Japan.


I can think of quite a few things to say about that nonsense, but I will confine myself to pointing out that it is off-topic, having absolutely nothing whatever to do with the title of the thread.


----------



## SheikRattleEnroll (Aug 1, 2007)

*Re: LED battlefield survivability*

You're right and I apologize, but so was the post I was responding to. I didn't bring up Iraq, WWII, the current leadership of America and the American military, the validity of killing civilians to attain military objectives, the ability of the current leadership to handle a war like WWII, etc. I just responded to all those points, so don't just complain to me for thread crapping, there were at least two guilty parties here, and cutting up my post just makes three.



DM51 said:


> I can think of quite a few things to say about that nonsense, but I will confine myself to pointing out that it is off-topic, having absolutely nothing whatever to do with the title of the thread.


----------



## gearbox (Aug 14, 2007)

*Odd question: EMP effects on LED and incandescent*

I am wondering if either is more resistant to the effects of an Electromagnetic Pulse. I am thinking that the filament of an incan could be fragile and sensitive to an EMP surge, but the electronics of an LED's converter board is especially vulnerable. Perhaps an LED operated just by batteries and resistors without "electronics" would be most durable?


----------



## Grubbster (Aug 14, 2007)

*Re: Odd question: EMP effects on LED and incandescent*

Not an odd question. Questions on EMP effects are asked quite frequently. A search should give you all the info you need.


----------



## jbviau (Aug 14, 2007)

*Re: Odd question: EMP effects on LED and incandescent*

I don't know much about it, but the FAQ on the Arc AAA website addresses EMP issues:

http://www.arcflashlight.com/faqs.shtml

The Arc AAA (an LED light) is supposedly resistant to EMP effects.


----------



## gearbox (Aug 14, 2007)

*Re: Odd question: EMP effects on LED and incandescent*



Grubbster said:


> Not an odd question. Questions on EMP effects are asked quite frequently. A search should give you all the info you need.



Will do!


----------



## markfinn (Oct 26, 2007)

*Will LED flashlights survive the EMP from a nuclear explosion?*

Not that I ever want a live demonstration by someone...

This entirely theoretical question came to my mind when I read an article on electromagnetic pulses (by natural lightnings, microwave experiments - and nuclear weapons).
It said that most semiconductors within a certain zone around will be at least damaged - would the same happen to LEDs in modern flashlights or is the common aluminum housing protection enough?
So this could be the last reason/field of application for incans in military and civil defense area?

Probably someone with military background knows the answer?
Hope I will not receive the 'stupid question of the day' award... 

Thanks,
Mark


----------



## gearbox (Oct 26, 2007)

*Re: Will LED flashlights survive the EMP from a nuclear explosion?*

I asked the same thing here a few months ago, thinking I was of an uncommon thought. Evidently it has been discussed ad nauseum....but the discussion is never resolved 

Ultimately, there is no way to determine if your light will survive. You can't calculate it since there are so many variables, so the only way to know is....to test an EMP. They scatter pulses of a specific wavelength, and can be absorbed by a faraday cage if it's properly designed and executed. Supposedly the metal bodies of lights can decrease the chance of losing a light, but how can that be tested in its entirety?

Also, the pulse could ruin either the electronics, the emitter, or both. I'm not sure the emitter itself is or is not more/less susceptible than the semiconductors of the circuit board. :thinking:


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## light_emitting_dude (Oct 26, 2007)

*Re: Will LED flashlights survive the EMP from a nuclear explosion?*

If your that close enough to a nuclear explosion, you won't have to worry about your lights.


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## markfinn (Oct 26, 2007)

*Re: Will LED flashlights survive the EMP from a nuclear explosion?*

Thanks, to be honest I haven't used the forum search since I thought this was a very uncommon question...I'll have a look at the existing thread.

I read that there are small 'devices' (backpack size) based on nuclear chain reaction that are primarily designed for EMP and not for nuclear blast (and explosion damage, fallout etc.) so that there would be a very realistic chance of physically surviving this disaster but with all electronic communication and computer equipment destroyed, i.e. infrastructure damages that could already defeat a country.
Is this EMP device just a fairy-tale or really possible?

Thanks,
Mark


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## svander07 (Oct 26, 2007)

*Re: Will LED flashlights survive the EMP from a nuclear explosion?*

thought you could have an EMP without the nuke and that an EMP will not harm anything biological?


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## WadeF (Oct 26, 2007)

*Re: Will LED flashlights survive the EMP from a nuclear explosion?*

Properly shielded, I think components can be protected from EMP. Maybe the aluminum bodies most our LED's are in would protect the LED? Of course the glass may not do much. Maybe if you're worried about it you could keep your lights stashed in some kind of copper mess bag. I noticed on these shows when they played around with EMS weapons they would cover themselves and their gear with some kind of copper mesh. Basically just shielding themselves like you'd shield a wire.


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## gearbox (Oct 26, 2007)

*Re: Will LED flashlights survive the EMP from a nuclear explosion?*



markfinn said:


> Is this EMP device just a fairy-tale or really possible?



Both, really. Baddies of late seem to be using mostly improvised conventional destruction, and only dabbling in the high-tech. Madrid, London, Indonesia, Thailand, WTC, Iraqi insurgency, etc.. It is all conventional explosives. That's not to say that it's not possible, only that there doesn't seem to be much evidence to support the idea that we would be attacked in other ways. For instance, there have been radiation poisonings in the former KGB. Dirty bombs are more likely here, then full-out nuclear, with EMP-specific weapons being low on the list...but who knows for certain?


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## leprechaun414 (Oct 26, 2007)

*Re: Will LED flashlights survive the EMP from a nuclear explosion?*

This is a great question. I think anything with electronics runs the risk of being "fried" by an EMP. I think there are many factors such as how close you are, size of explosion etc that would come into play. It would be interesting to hear some theorys about this topic.


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## Patriot (Oct 26, 2007)

*Re: Will LED flashlights survive the EMP from a nuclear explosion?*



svander07 said:


> thought you could have an EMP without the nuke and that an EMP will not harm anything biological?


 
You can have an EMP without a nuclear explosion but nothing of the scale or order that nuclear weapons produce.


Even good old wikipedia has good info about EMP:

http://en.wikipedia.org/wiki/Electromagnetic_pulse


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## dk8558 (Oct 26, 2007)

*Re: Will LED flashlights survive the EMP from a nuclear explosion?*

There was actually a segment on the Future Weapons show of a device that can fire an EMP. During the show they demonstrated a scenario which they used a EMP device to disable a car that refused to stop at a road block. The host was driving at the time of the pulse and he wasn't injured but the car he was driving suddenly stopped. pretty cool.


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## Marduke (Oct 26, 2007)

*Re: Will LED flashlights survive the EMP from a nuclear explosion?*

The LED's themselves, maybe, I'm not sure. The circuitry that regulates all but direct drive lights, 

One scenario that most people forget is *one* nuclear blast detonated about 100 miles in altitude would bath around 1/2 of CONUS with a strong enough EMP to wreak havoc. It would cause much more economical damage than targeting a single city. But like others mentioned above, you'd have bigger problems than if you can use your LED flashlight or not.


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## TigerhawkT3 (Oct 26, 2007)

*Re: Will LED flashlights survive the EMP from a nuclear explosion?*

Perhaps this discussion should continue at one of these threads:

_(Moderator note: several threads merged, inactive links removed. Thank you!)_

The Search function can be finicky, but it mostly works.


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## MarNav1 (Oct 26, 2007)

*Re: Will LED flashlights survive the EMP from a nuclear explosion?*

Better keep some X5's around!


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## Patriot (Oct 26, 2007)

*Re: Will LED flashlights survive the EMP from a nuclear explosion?*



dk8558 said:


> There was actually a segment on the Future Weapons show of a device that can fire an EMP. During the show they demonstrated a scenario which they used a EMP device to disable a car that refused to stop at a road block. The host was driving at the time of the pulse and he wasn't injured but the car he was driving suddenly stopped. pretty cool.


 
I saw that 

They also disabled a RC helicoper in flight with a generated EMP during the same program. It was very interesting.


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## gearbox (Oct 27, 2007)

*Re: Will LED flashlights survive the EMP from a nuclear explosion?*



MARNAV1 said:


> Better keep some X5's around!



The Inova lights? What's special about those?


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## 270winchester (Oct 27, 2007)

*Re: Will LED flashlights survive the EMP from a nuclear explosion?*

I have a bunch of simple incandescent Surefires around. those are the least likely to be affected by EMPs as far as I understand.


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## AzN1337c0d3r (Oct 27, 2007)

*Re: Will LED flashlights survive the EMP from a nuclear explosion?*

Aren't flashlight bodies usually part of the circuit? Thus they don't act to shield the electronics inside.


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## Marduke (Oct 27, 2007)

*Re: Will LED flashlights survive the EMP from a nuclear explosion?*



gearbox said:


> The Inova lights? What's special about those?



The Inova X5 is about as perfect as you can get for an emergency light. It will run on dead batteries that won't even glimmer in other lights, it will run like that for weeks, uses lithium batteries with a 20 year shelf life, extremely reliable and rugged construction, and doesn't contain sensitive regulatory circuitry. It's a simple direct drive light, with only some resistors. For these reasons, it is often lovingly called "bomb proof"


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## Marduke (Oct 27, 2007)

*Re: Will LED flashlights survive the EMP from a nuclear explosion?*

Oh, and an aluminum body would offer no protection. Only a Faraday cage would offer any sort of protection short of several feet of earth, concrete, or metal.


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## Skibane (Oct 27, 2007)

*Re: Will LED flashlights survive the EMP from a nuclear explosion?*

The amount of damage that can be produced by HEMP (EMP produced by a high-altitude nuke detonation - the only kind of EMP that is likely to be encountered by anyone living more than a few miles from a high-value military target) - has been GREATLY exaggerated on the internet.

EMP does its damage by inducing a very brief, high-voltage spike in electrical devices. This spike can be strong enough to burn out wiring, "punch through" the thin semiconductor layers in transistors, computer chips and diodes, or cause the software in computer-controlled devices to go haywire. 

However, the strength of the electrical spike induced in any electrical device by a HEMP burst is dependent on the length and physical orientation of any conductors connected to the device. Long conductors (i.e., AC power lines, phone lines, big antennas, etc.) receive a significant amount of the EM pulse; short conductors do not.

In devices that aren't connected to any long conductors, virtually no electrical spike is generated due to EMP, and thus *the device is unlikely to be damaged*. Most small electronic devices (i.e., cell phones, portable radios, PDAs, laptop computers, digital wristwatches, flashlights, etc.) would fall into this category - The few inches (or fractions of an inch) of conductors present in these devices is simply too short to intercept any significant amount of the EM pulse, and thus no damaging voltage spike is generated within them.

Similarly, the short length of the wires present in most vehicles (automobiles, motorcycles, ATVs, etc.) also intercepts very little of the EM pulse - and thus, is unlikely to be damaged. Also the wiring in most vehicles is partially shielded by the vehicle's metal body (thereby further reducing the strength of a voltage spike induced), and all vehicle electrical systems are designed to deal with the high voltage spikes normally produced by the ignition system, motor brushes, relay and solenoid coils, etc.

Several practical examples:

1. During the Starfish Prime high-altitude nuclear test conducted on July 9, 1962, it was reported that EMP effects caused damage to streetlights in Hawaii (some 930 miles away), and yet portable radios located on Johnson Island (directly under the nuclear burst) were undamaged. Explanation: The portable radios lacked any large antennas or other connections to long conductors, and thus didn't receive enough of a spike to be damaged.

2. The American Radio Relay League (ARRL) reprinted a series of articles (originally published for the National Institute of Standards) that described the effects of EMP on various communication equipment:

Intro to EMP
EMP Protection Devices
EMP Implications for Communications
EMP Protection for Communications

These tests demonstrated that even very sensitive equipment is unlikely to be damaged by EMP, provided that the equipment doesn't have any connections to long conductors.

*BOTTOM LINE:* All of your flashlights stand a good chance of being usable after a HEMP burst, even without taking any special precautions beforehand.


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## d1337 (Oct 27, 2007)

*Re: Will LED flashlights survive the EMP from a nuclear explosion?*

On the bright side if your flashlight does fail after the nuke you will probably glow in the dark for a couple of weeks anyway. :sick2:


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## Bushman5 (Oct 27, 2007)

*Re: Will LED flashlights survive the EMP from a nuclear explosion?*

its really quite simple, line your backpack, clothes, vehicle, and house with mass amounts of tinfoil adn copper mesh, and wear a tinfoil hat!! 












:laughing:


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## Sigman (Oct 27, 2007)

*Re: Will LED flashlights survive the EMP from a nuclear explosion?*

Several like threads merged...


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## markfinn (Oct 27, 2007)

*Re: Will LED flashlights survive the EMP from a nuclear explosion?*

Thanks to you all (in particular to Skibane!) for the explanations!
At first I was a little afraid that you would make me look like a fool for this question, but again it was a pleasant surprise to see these knowledgeable people here. That's what I like CPF for!!!


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## Dr Jekell (Oct 27, 2007)

*Re: Will LED flashlights survive the EMP from a nuclear explosion?*

From my understanding of it an EMP is comprised of Electro Magnetic Waves, Which is like TV signals, AM/FM Radio, cell phones, transceivers (Portable Radios), ham radio, microwave transceivers, etc but over many bands instead of just one or two.

This would indicate that if an item were to be damaged it would need to have something either attached or built into it that would act like an antenna (like the one for your TV, car radio, power lines & pylons, phone lines) to attract any of the EMP.

So this would debunk the idea your LED lights (with or w/o electronics) would not survive an EMP as they have very short amounts of wire in them to act as an antenna.

The same could be said for small electronics (exceptions exist) to survive as well.

Items like laptop computers, cell phones, MP3/CD/Tape players, are a toss up as to whether or not it would

A) Develop a Fault that can be fixed or gotten rid of
B) Be damaged or 
C) Killed 

There is a similar problem that is more widespread & catered for is EMI or electromagnetic interference (if you look on the underside of almost any electronic device & you will see a sticker stating that it has been tested for this, most will be tested to the FCC standards which I believe most countries accept - go ahead & have a look under you desktops keyboard)

This may also provide some protection for items like laptops & cell phones as they may have shielding built into them to reduce EMI.

This is my understanding of EMP theory but it may have errors so take it with a grain of salt.


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## Mr_Dead (Oct 27, 2007)

*Re: Tin foil?*



h_nu said:


> I'm pretty sure you are right. Many Americans use the term "tin foil" when they really mean Aluminum foil. People raised in the 40's and 50's called it that and their children probably flunked chemistry.



They still use it to seal the ends on wine bottles (the "capsule", protecting the cork). In fact, that's more likely to be real TIN foil, than the cork is to be a real cork these days, but you might not have noticed unless you look closely.


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## h_nu (Oct 27, 2007)

*Re: Tin foil?*



Mr_Dead said:


> They still use it to seal the ends on wine bottles (the "capsule", protecting the cork). In fact, that's more likely to be real TIN foil, than the cork is to be a real cork these days, but you might not have noticed unless you look closely.



I didn't realize the foil was Tin. I did notice a synthetic cork on a bottle of Sangiovese Toscana. It even felt like cork.


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## Don_Redondo (Oct 27, 2007)

*Re: Will LED flashlights survive the EMP from a nuclear explosion?*

The antenna theory makes sense. My house has gone through quite a few near lightning misses – comes with living near the top of a hill. On two separate misses I had network ports damaged. A couple on a router and one on a workstation. The router and it’s replacement got damaged a year apart. Since all the computer outlets are surge protected, no lights flickered, and no other electronic equipment in the house was damaged, it doesn't seem like it was a surge on the AC side. The most likely explanation is that the charge differential before the strikes induced a brief excess voltage in the network cables and fried the ports. The intriguing thing is that the routers only lost a couple ports – each time - and they weren’t always the ones with the longest cables attached – the orientation must have played a part – which was mentioned as a factor with the EMPs. (The router was under warranty and replaced – both times. Since the service was more than I expected here’s a mini cheer for SMC.) Another interesting thing was that the workstation was only crippled and will only connect at 10mbs instead of the 100mbs before the miss. And yet another weird thing was that a laptop turned itself on at the same time. My assumption was that the pulse in the network cable triggered some “wake-on-lan” function but I never found out the exact reason and it never happened again. It was pretty spooky since I was right next to it at the time. 

While this is not the same thing as an EMP, I imagine the effects may be similar – some things damaged and some things OK. As for the effect on lights, all this happened before I had any LED flashlights but to the best of my knowledge, none of my incandescents went .


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## Confederate (Oct 31, 2007)

When I worked with the Navy, a lot of the R&D had to do with hardening electronics from electro-magnetic pulse. Now with intelligence fears of a nuclear detonation over the U.S., everything from computers, televisions, radios and even motor vehicles are threatened.

I believe the circuitry in these small lights also would be affected, but if so, how can they be protected? I've heard of makeshift Faraday boxes, but if the lights can be protected in any other way, I'd like to know about it. I need only protect very small items at this point. I also wonder if batteries would be damaged. I know rechargers and solar power units would be fried.

Thanks for any info!


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## PhantomPhoton (Oct 31, 2007)

Theres been quite a discussion on this before. Unfortunately searching for EMP didn't work for me but I was able to find this recent thread via other methods.

Here


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## joema (Oct 31, 2007)

Discussed extensively here:

_(Moderator note: Merged like threads, edited out inactive links - THANKS joema!)_


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## Confederate (Oct 31, 2007)

Thanks! Just what the doctor ordered!


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## Sigman (Nov 1, 2007)

Thanks for the links joema...I'm merging the threads & will edit out the inactive ones.


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## mzzj (Nov 1, 2007)

*Re: Tin foil?*



Mr_Dead said:


> They still use it to seal the ends on wine bottles (the "capsule", protecting the cork). In fact, that's more likely to be real TIN foil, than the cork is to be a real cork these days, but you might not have noticed unless you look closely.



And orginally "tin foil" was lead, not tin.


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## democopy (Nov 1, 2007)

"Every flashlight I own is an LED based one (and quite a few of the brands you mentioned). As far as any kind of EMP pulse destroying or damaging it, the only type that will is going to be a strike from a e-bomb/HPM (High Powered Microwave) based EMP system, and even with the e-bomb/HMP attack it would be hard pressed to actually damage the unit.. The reason for this is simple, there are no long lines in the circuitry of the flashlight, so HEMP blasts and nearby lightning strikes are not going to "couple" their energy into the unit to destroy or damage anything. Microwaves (what e-bombs/HPMs use) could damage or even destroy them IF enough of the energy was coupled into the circuitry. The fact that most good LED flashlights (like the ones you mentioned) are in a metal (usually aluminum or titanium) case, thereby creating an improvised Faraday cage around the electronics. This further keeps the microwave energy from gaining any ground in the destruction of your flashlights. When I was doing the tests back in the lab (back in the 90's) I carried my CMG Infinity LED flashlight with me always on my keychain. It went through thousands of pulse repetitions og HEMP during those years, and dozens of MHD tests, and I still have it today and use it often. I even used it to provide the light source during some of the "close in" tests that we did with the Vircator and certain military gear.

Given the fact that an e-bomb/HPM attack is a very strategic strike (a few city blocks is maximum effective coverage), they probably are not going to go wasting them around the countryside, but rather use them to strike VERY high importance targets, so unless you are at a military base, or at a major infrastructure point, I would bet that your area will never see a microwave attack.

EMP damage is easy to remember, EMP will only damage things that are connected to wires longer than one half wavelength of their frequency, and even at one full wavelength it is not coupling much of the signal. To find the length of a half wavelength, divide 468 by the frequency in megahertz. For HEMP and other coil-only (HF and lower frequency) based systems, this means long wires. HEMP's (and coil-only EMP's) range is from <100KHz to 18MHz before it starts dropping the power levels quickly, with the majority of the power concentrated below 6MHz. At 6MHz, a half wavelength piece of wire is 78 feet long, at 18MHz, it drops to 26 feet. This is why HEMP will not bother handheld devices or devices that are not connected to long lines, the grid or big antennas. E-bombs and HPMs are much higher in frequency, usually in the 950MHz to ~24GHz (24,000MHz) range. At 950MHz a half wavelength piece of wire is 5.9 inches, and the upper end of 24GHz is only *.*234" (1/4 of an inch) long. This is why e-bombs and HPM weaponry has the possibility of damaging ANYTHING outside of a Faraday shield, because the electronic component's leads, and the circuit board traces are long enough to couple the energy into the device without the need of long wires or grid connections. The good news is that most of the good flashlights are mostly shielded by their metal cases.

In other words, I would not worry about the possibility of the threat."


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## h_nu (Nov 2, 2007)

I have more realistic things to worry about. That said, I have wondered about something though.

In the 80's, when the public became aware of neutron bombs, many people were surprised that the bomb models were sophisticated enough to allow the designs to be tuned to produce mostly neutrons and limit blast effects. Perhaps there are designs that focus most of the energy produced in the microwave region and the EMP could be substantially higher than ordinary bombs.


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## Marduke (Mar 25, 2008)

*Re: EMP ?*

Try here:
http://www.google.com/search?hl=en&sitesearch=candlepowerforums.com&q=emp&btnG=Search
http://www.google.com/search?hl=en&...orums.com&q=electromagnetic+pulse&btnG=Search
http://www.google.com/search?q=nuclear&sitesearch=candlepowerforums.com


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## Marduke (Mar 30, 2008)

*Re: emp wipe out all led ? for boogey bag use*

They are fine. I suggest trying out the "search" function

http://www.google.com/search?q=emp&sitesearch=candlepowerforums.com
http://www.google.com/search?hl=en&...orums.com&q=electromagnetic+pulse&btnG=Search
http://www.google.com/search?hl=en&sitesearch=candlepowerforums.com&q=nuclear&btnG=Search


BTW, :welcome:


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## Sigman (Mar 31, 2008)

*Re: emp wipe out all led ? for boogey bag use*

Marduke, thanks for the links...I just merged "several" existing threads on the same subject and ended up with these 373 posts!

Therefore...I'll lock this one down, & we can continue in the new thread here.


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