# LED compared to Halogen



## LightTracker (Dec 12, 2008)

I'd like to get back to adventure lighting and hope not to guess at what I need. 

My old halogen system was a 12w spot - 20w flood combination converted from a bike light. I wouldn't want anything less bright than that.

How many lumens of LED would be similar in brightness to 32 watts of halogen?

(Hoping for some enlightenment)
Dan


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## LukeA (Dec 12, 2008)

Two Crees with the proper optics would equal that output. You could run four Crees, two with narrow optics, two with wide, and thoroughly outclass your current system while still halving power consumption.


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## LightTracker (Dec 16, 2008)

Hey, thanks for the response. Is there a system out there that is equivalent to one of the two options that you described? Maybe one narrow model and one wide... or one with a side-by-side setup?

Or, is there a forum that would tell me where to buy the materials to make my own setup? I'm a total newbie so patience is appreciated. All I know about Cree is it's a brand of LED light, and beyond that I'm blank.

Thanks!


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## blasterman (Dec 16, 2008)

[QUOTE*]*How many lumens of LED would be similar in brightness to 32 watts of halogen?
*[/*QUOTE]

That's about 350Lm...assuming a really good reflector. Easily matched by just a couple of Q5 or R2 Crees.

One or two narrow optics in the middle and two floods on the sides - yup, that's what I would do.



> and thoroughly outclass your current system


...Along with 99% of oncoming traffic - especially the idiots using those cheap, purple tinted halogen driving lights :twothumbs


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## LukeA (Dec 16, 2008)

Here is a very good read.

SSCs are equivalent to Crees in output.


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## LightTracker (Dec 17, 2008)

Thanks Blasterman for the info and thanks LukeA for the article. I couldn't find an objective comparison of the Q5 and R2, only some pics where the R2 looks a little wider and brighter than the Q5 (shown on this page.)

The article inspired me to do some research though, and I found this project -- uses 4 Luxeon LEDs, a computer PC heatsink (hack-sawed to fit),  parts costing 80.00. Is this too challenging for a newbie? 

Not sure I like the Cyan color light. The author says this achieves the best visibilty for a human eye and consumes less power... But, if you prefer white light, just opt for white color LEDs. I guess you can't know what you'll have until you try.

I wonder, can beam spread be varied? Is this possible with LED? Similar to a Brinkman or MagLite focusing head? I wonder what it would take to achieve that without machine tools? Any ideas? Maybe I should start out smaller.

Again, Thank you for the input! (I'm feeling a little more enlightened from reading.)


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## LukeA (Dec 17, 2008)

LightTracker said:


> Thanks Blasterman for the info and thanks LukeA for the article. I couldn't find an objective comparison of the Q5 and R2, only some pics where the R2 looks a little wider and brighter than the Q5 (shown on this page.)
> 
> The article inspired me to do some research though, and I found this project -- uses 4 Luxeon LEDs, a computer PC heatsink (hack-sawed to fit),  parts costing 80.00. Is this too challenging for a newbie?
> 
> ...



Those images are misleading. Differences in aim cause the camera to capture different amounts of light. In real life, the R2 will be imperceptibly brighter, but beam pattern will be exactly the same. 

Luxeons are half as efficient as Crees and SSCs. 

The cyan guy is full of crap. The Lumen measurement already accounts for differences in sensitivity of the eye to different wavelengths of light. White LEDs are higher in lumens, and so are brighter. 

No, you can't do that without a metal lathe.


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## LightTracker (Dec 17, 2008)

LukeA said:


> Luxeons are half as efficient as Crees and SSCs.



Is there any advantage to Luxeon that makes up for it's inefficiency? Size? Output? Maybe the lenses or switches that are pre-fabricated for it? That design gets 3 hours of runtime and it outputs 500Lm and it weighs 480 grams (w/batteries). It's more efficient than my old halogen system by far.

But it may not be the design I want. Are there other designs out there that you know of? The advantage to this one (for me) is that it's pretty compact and looks to configures pretty well for a headband, including a vertical rotation device. I can also order everything online.

The author says he's driving the LEDs at 2W instead of 1W, can dissipate the heat no problem. Also, different lenses are available for the mounts, you can tailor it to your needs by changing them on the fly. They come in 5 degree, 15 degree, 25 degree and 5x25 degree at $1 each.

So you think there is hype in that article and I should keep looking? Does anyone around the forum have experience making an LED adventure light who you know? I'd like to pick as many brains as I can. Else, I'll remain unenlightened. I'd like to change that if I can....

Thankee kindly,
Dan


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## gillestugan (Dec 17, 2008)

For homebuilt and modded headlamps: take a look in the headlamps forum. There are a few threads in there.
Small and nice DIY lights for helmet mount are also found over at the MTBR forum. You may see some very nice and innovative designs there.

The housing and mount is the trickiest part in making headlamps as you want it as light as possible. Light, small and efficient heat sinking is not an easy combination. 
The original luxeons have no real advantages over Cree XR-E and SSC P4.


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## blasterman (Dec 17, 2008)

LukeA said:


> The cyan guy is full of crap. The Lumen measurement already accounts for differences in sensitivity of the eye to different wavelengths of light.


 
Yeah....that made me chuckle. With equal absurd logic I could argue you should use Red LED's because they don't cause your pupils to contract under low light. Plus, you could walk up to people and say "I am Borg". If I see a hiker walking around in the woods at night with a blue/cyan LED I'll know who to blame at least.

You'd think by now we'd be done explaining that 'white is not a color, but a combination of colors'.


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## LukeA (Dec 17, 2008)

LightTracker said:


> Is there any advantage to Luxeon that makes up for it's inefficiency? Size? Output? Maybe the lenses or switches that are pre-fabricated for it? That design gets 3 hours of runtime and it outputs 500Lm and it weighs 480 grams (w/batteries). It's more efficient than my old halogen system by far.
> 
> But it may not be the design I want. Are there other designs out there that you know of? The advantage to this one (for me) is that it's pretty compact and looks to configures pretty well for a headband, including a vertical rotation device. I can also order everything online.
> 
> ...



No. None. Luxeons have no advantages over Crees or SSCs of any kind. That system doesn't put out 500 lumens. More like 200, tops. 

There's an even wider selection of optics for Crees and SSCs. SSCs can use any luxeon optic.

That triple Cree/SSC thing from Bikeled.org is what I think you should build.


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## LightTracker (Dec 18, 2008)

LukeA said:


> Luxeons have no advantages over Crees or SSCs of any kind. That system doesn't put out 500 lumens. More like 200, tops.
> 
> That triple Cree/SSC thing from Bikeled.org is what I think you should build.



You must mean this?







It's advertised output is 600 Lm taking into account 10% loss from optics. It uses 3XSSC P4 (u-bin) What does u-bin mean? It says 2x15 degree and 1x5 degree optics, must mean beam width? Sounds similar to what Blasterman talked of, narrow beam wedged between two wider ones.

I'm going to do some checking, use the other forum too... thanks for that tip. 

It looks like this could be built with plain tools. Cost may be a little over 100.00 (with the right suppliers). For a 600Lm rechargeable LED light...? Not too painful, even in these times. It has vertical rotation. I could use the Velcro pads put it on a headband.... (one less Cyan beam wandering in the woods)

You guys are a great help! See you in the funny pages.
LightTrackerDan:thumbsup:


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## LukeA (Dec 18, 2008)

LightTracker said:


> You must mean this?
> 
> 
> It's advertised output is 600 Lm taking into account 10% loss from optics. It uses 3XSSC P4 (u-bin) What does u-bin mean? It says 2x15 degree and 1x5 degree optics, must mean beam width? Sounds similar to what Blasterman talked of, narrow beam wedged between two wider ones.
> ...



Yep, that's the one. 

It's a great first light because it's a good design and because there's a nice walkthrough with pictures of its construction. It will also be very bright. 

Yes, those angle measures refer to beam divergence. 

It will probably get hotter on your head than on a bike helmet (because there's less airflow), so you may want to add some aluminum fins. You might not need to though. 

U-bin is a brightness bin. A U-bin SSC P4 will put out at least 91 lumens at 350mA, typically 100 lumens at 350mA. 

Here is a picture of the beam pattern.


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## LightTracker (Dec 18, 2008)

LukeA said:


> U-bin is a brightness bin. A U-bin SSC P4 will put out at least 91 lumens at 350mA, typically 100 lumens at 350mA.



Thanks for the picture, that heps. So how can the bikeled.com light (3 P4s) put out 600 lumens when a single P4 puts out 91 lumens?

You're right about the type of project, since I'm a noob I need it more basic. I think the project is doable for me. The author, Allen Chapman, left his email link and I already contacted him.

I'm a computer tech by trade, so I could use an old PC heatsink to dissipate heat (Cyan light guy tip, may not be a bad idea) 

Looking back at my former question, I'm no sure varying beam divergence is an option other than having a selection of different lenses. LED lights are flat and there's no way to change the focal point, it's not a point source, it's more of a blob. Is this correct?


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## yellow (Dec 18, 2008)

> Is there any advantage to Luxeon that makes up for it's inefficiency? Size? Output? Maybe the


Hey Dan,
see it that way:
even at the time the guy had that idea, it was a bad one
but the Luxeon emitters were the best *at that time*

but that short time now is already *stone age *when it comes to Led - progress in just that short time is astounding

--> Cree XR-E / Seoul P4



PS: higher lumen is, because that 350 mA rating is nice but the led are driven at about 800-900 mA
(which could be considered as "safe" level - when heatsinking is good)


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## LukeA (Dec 18, 2008)

LightTracker said:


> Thanks for the picture, that heps. So how can the bikeled.com light (3 P4s) put out 600 lumens when a single P4 puts out 91 lumens?
> 
> You're right about the type of project, since I'm a noob I need it more basic. I think the project is doable for me. The author, Allen Chapman, left his email link and I already contacted him.
> 
> ...



The P4s typically put out 100 lumens at 350mA. This project calls for the LEDs to be driven at 1A, where the LEDs are rated for 240 lumens each. 

Some or all of a finned computer heatsink on top of the light will work fantastically. 

Well, all the light in a P4 comes from a little square die 1mm on a side, so the surface brightness is of a level similar to an incandescent bulb. But yes, it is fairly difficult to have a system that allows significant variance in LED height. And you can't do it with TIR optics like the ones in the bikeled.org light. TIR optics are very sensitive to light source height. The only system that effectively allows the light source to move vertically in a reflector is the Maglite. But with LEDs and TIR optics you can get a beam that provides both near-field illumination and far-field illumination simultaneously.


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## LightTracker (Dec 21, 2008)

LukeA said:


> The P4s typically put out 100 lumens at 350mA. This project calls for the LEDs to be driven at 1A, where the LEDs are rated for 240 lumens each.


 
Thanks fro that explanation.



LukeA said:


> the light in a P4 comes from a little square die 1mm on a side... fairly difficult to have variance in LED height. --with LEDs and TIR optics you can get a beam that provides both near-field illumination and far-field illumination simultaneously.


 
The kid in me wants it to be able to focus all the available lumens, but it's not a huge loss, I guess, considering the whole beam of the LED system is bright (white) and illuminating.

Thanks Yellow, for that about Luxeon how fast the technology can change... I see Mr Chapman is showing P4 compared to XR-E here: Both are triple light arrangments. The P4 seems to outperform a bit, was that due to modifying his reflectors or is it a better design? I'm not sure I like the hotspot of the P4 arrangment, might look better farther away from the shrub...?

Since the technology is changing rapidly, is it better to wait for lumens/cost ratio to improve? Will the heat sink issue be improved? Is that only an issue when you overdrive these lights? Do you thihk there will be a time in the future when you can buy a kit for say 20.00 which will outperform what we're seeing now? Just curious... 

Thanks again for the info,
LightTrackerDan


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## LukeA (Dec 21, 2008)

LightTracker said:


> The kid in me wants it to be able to focus all the available lumens, but it's not a huge loss, I guess, considering the whole beam of the LED system is bright (white) and illuminating.
> 
> Thanks Yellow, for that about Luxeon how fast the technology can change... I see Mr Chapman is showing P4 compared to XR-E here: Both are triple light arrangments. The P4 seems to outperform a bit, was that due to modifying his reflectors or is it a better design? I'm not sure I like the hotspot of the P4 arrangment, might look better farther away from the shrub...?
> 
> ...



There's been about a 25% improvement in Cree brightness since that thread was made. Those are P3s or so, now there are Q5s and R2s. 

If you wait for the lumen/cost ratio to get better you'll have to ride behind a dim orange glow for a while. 

Bike lights are pretty easy to heatsink because you've got so much airflow. 

Probably someday, but then what you could get for $100 would still blow it out of the water.


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## LightTracker (Dec 26, 2008)

LukeA said:


> There's been about a 25% improvement in Cree brightness since that thread was made. Those are P3s or so, now there are Q5s and R2s.
> 
> If you wait for the lumen/cost ratio to get better you'll have to ride behind a dim orange glow for a while.
> 
> ...


 
Thanks LukeA. So Lumen/cost reduces by heatsinking because it allows the LEDs to live longer.

Q5s, R2s (whatever's next) don't need as much overdriving (hence heatsinking) for higher output, and if you have airflow it lessens the need to heatsink. 

So is heatsinking only necessary when you overdrive the light? If sheer output is your main aim can you just use a brighter light or more of them to achieve it?

Output IS my main aim, but what's the right balance between overdriving and heatsinking when you may not have airflow or cooler air? Maybe devise detachable heatsinks? 

Waiting behind the dim orange glow, yuk. I don't think so....

Thanks!! 
What do you think?


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## LightTracker (Dec 26, 2008)

Here is a light that claims 1500 lumens. I don't see a heatsink. How do they achieve that much output without heatsinking? Of course it costs over 1000.00, ouch!


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## shortstack (Dec 26, 2008)

any high power led (ie bigger then 1 watt) needs heat sink, and usually the more power you put to it the more it needs.


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## Jarl (Dec 26, 2008)

That does have a heatsink- the metal case of the light. Since this case isn't very big, it relies on the airflow to keep it cool rather than a large surface area.


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## LightTracker (Dec 26, 2008)

Its marketed as a bike-light set _or_ head-light set. If its used for caving or hiking there won't be much airflow. The ad says it uses 7 Seoul P4s driven from .25w to 23w... It must be either able to withstand more heat or you give up service life... or, you're expected to know not to drive it that high in those circumstances? What's the big deal with overdriving an LED with less heat dissipation? Is it the replacement cost? How much service life do you lose when you don't keep it cool enough?

Sorry to ask so many nagging questions. I'm a noob. Hope not to be that way forever... with your help I can change that.

Thankee kindly!


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## znomit (Dec 26, 2008)

LightTracker said:


> What's the big deal with overdriving an LED with less heat dissipation?



As the LEDs get hotter they put out less light, maybe 30% less. 
http://www.cree.com/products/pdf/XLamp7090XR-E.pdf

At 30 mph the wind provides a lot of cooling. This is the only time you'll need 1500lm. Most DIY bike lights are around 500-700lm. 
Running, 100-300lm is plenty.
Caving? 50lm?


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## R33E8 (Dec 26, 2008)

LightTracker said:


> What's the big deal with overdriving an LED with less heat dissipation? Is it the replacement cost? How much service life do you lose when you don't keep it cool enough?



In addition to what znomit said, the lifetime also goes down almost exponentially as it gets hotter...


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## LightTracker (Dec 29, 2008)

You guys a re a big help, LukeA, znomit, blasterman, R33E8.... 

The Lupine light (above) has 7 X P4s for 1500Lm maximum output. I'd like 300-400Lm for night hiking (mostly in the winter), and the DIY ideas are mostly geared toward biking and take account of the airflow.

I don't want to drive the lights to the point where heatsinking is a big concern. But I also would like the option to "crank it up" for a short time or when in icy cold temps.

The Lupine light must have a housing made of some special material as there is no visible heatsink. I assume my DIY light would be aluminum. What shoudl I use that can produce 300-400Lm with the least amount of heat issues for hiking, not biking?

Any ideas? Maybe one of the bike light ideas is best or could be adapted?

Thanks!


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## yellow (Dec 29, 2008)

for "usual" the lupines are mounted on a sinking plate and this is a press fit to the metal housing.
Gets heat away nicely and sits in the airflow to be cooled
additionally, they usually feature some kind of temp sensor that immediately drives the current down when they get too hot
(which, in the case of this light will be very quick without airflow. But that is not the question now)

the whole headlamp shows how to build a light *now!*

the led mounted onto a thicker alum. sheet, which is in direct contact to the housing, which acts as heatsink.
No more need for useless and heavy "real" sinks, which, as an additional point, make construction more difficult.

Better try the easy "at the moment" way:
search a light at Dealextreme (or any other "cheaper" shop) that You like.
Something with a quad-led setup, of maybe a Seoul P7 or Cree MC-E and which is able to run from Your power source (check input voltage).
Use only the light head of it, mod the back side with an end plate, switch, connections, cable to batt pack.
pro: cheap, very nice looking, some parts for future projects present (housing, led mounting/thermal plate), front glass, o-rings, ...)

there is a high chance You like it,
if not, You can mod it with other led, another driver, better focusing devices, ...
(for less money and much less work than when building lights from diverse "how-to"s (the ones giving You more work than necessary to end up with a light that looks homemade))

One important improvement of the multiled: beam shape widening!
--> dismantle led, scrape led mounting spots a few degrees out of the main axis (3-4 degrees), mount led again, mount focusing.
instead of a very bright, spotty main beam --> a wider, but less bright hotspot


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## LightTracker (Dec 29, 2008)

Hey yellow, Thanks for that info. I need to take a while to digest it and I promise to respond in a few days. IT looks like I need to do some reserach here. Again, Thanks!


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## LightTracker (Dec 30, 2008)

I looked at DealExtreme. They have LED flashlights at 200 lumens (+ or -) from 10.00-20.00. The issue would be configuring a couple (or 3?) for a usable beam for hiking, also concerned with power and charging. Could I realistically achieve 300-400Lm without an external heatsink?

Why is no external heat-sink required with those?
Is it that the mounting plate is not shared with several brighter LEDs? So you're pouring less heat into it?

I like the idea of having a more professional look and fairly cheap probably less work than many other DIY projects. Has somebody configured a headlamp this way before that you could link me to?

Thanks!!


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## dom (Dec 30, 2008)

Hi Dan
You will need external heatsinking for that amount of lumens.

You do understand the theory of an aluminum light body acting as a heatsink itself,if the LED is thermally
connected to it?

That is how those lights are cooled -plus your hand is also acting as a heatsink by transferring the heat from the light body ,to yourself.

Check this one out -haven't seen a simpler headlight yet 
Just a P60 dropin available from DX or KD -very cheap and variable voltage input and many types available.

http://candlepowerforums.com/vb/showthread.php?t=212401

Cheers
Dom


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## LightTracker (Dec 31, 2008)

Hi, and thanks!! So this 230Lm flashlight at Deal Extreme doesn't require an external heatsink because your hand acts as a heatsink? And because its not 300-400Lm? 

If I took two of those and mounted them on my headband (not that I would, just making a point) wouldnn't I have 430Lm without an external heatsink? What am I missing?

Still Unenlightened,
LightTrackerDan


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## LightTracker (Dec 31, 2008)

*230Lm flashlight X 2 = 460Lm ... ?*


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## dom (Dec 31, 2008)

Hi Dan
If that dropin in the light has good thermal connection with the body -then no - no further heatsink would be needed.

You could probably leave it full power sitting on the bench and it would be fine.

You are thinking of heatsinks in the terms of the finned ones but any metal can be a heatsink no matter what the shape.

That one you show should have enough surface area and mass to easily dissipate the heat, though there is some formula that probably says i'm wrong 

As mentioned before -you can get drivers with thermal sensing that cuts current back when a certain temp is achieved -and also airflow is a major factor in keeping lights cool 
if you have a smaller light body running higher current.

Looking at Alans triple light -which is very lightweight and small -it can be run at high current no problems because air is running over it as you are riding.

Otherwise if sitting in still air at the same current -it would overheat in 7 mins if everything was well connected thermally.

Cheers
Dom


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## LightTracker (Dec 31, 2008)

dom said:


> Hi Dan
> You will need external heatsinking for that amount of lumens.
> 
> You do understand the theory of an aluminum light body acting as a heatsink itself,if the LED is thermally connected to it?
> ...



Hi, Thanks yellow and Dom!!
This light (see image below) is supposed to put out 230Lm if it has the proper Cree Q5 emitters. Wouldn't two of these put out 460Lm then? I agree it would be clumsy to put that on top of your head, but I'm trying to understand this issue better. That would cost 35.00, no heat-sink, and no gluing or soldering...I'sd just need to buy a charger. Am I missing something? (I'm sure I must be)
Thanks! (hoping for enlightenment) --Dan


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## LightTracker (Dec 31, 2008)

Somebody should design ear muffs that can act as a heat-sink, esp. on a day like this (-5 degrees, brrr...)

Cheers!


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## dom (Jan 1, 2009)

Hi Dan
Sure -they would work fine on a helmet -a few people have done that and are happy with the arrangement.

The main problem is aiming them in the right place and getting them to stay there.

Search for threads in the bike light section and someone should be able to help out there.

I think this thread might be getting off track about being LED specific though 

Cheers
Dom


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## LightTracker (Jan 1, 2009)

Thanks, Dom.... I meant to compare LED compared to halogen mainly to understand if or why the old would give way to the new (stop waiting behind the dim yellow glow?) Also because I want to find the equivalent to my old halogen headlamp system that was a 32 watt flood/spot combo. There are several ideas toward that: 

Buy new, spend 500.00.. or 1000.00?

Build a DIY bike light adapt to a headlamp and risk using without airflow.

Modify cheaper LED flashlights, figure out how to heat-sink them and mount them.

Mount a couple of flashlights and assume sufficient heat-sink is in the housing.

I'm trying to eliminate the lesser options first and learn why at the same time, also see what others are doing try to benefit by their mistakes.

I started looking at Petzl, etc... some (probably intentionally) don't advertise their output and are pretty high priced. Turning those on in a fluorescent lighted store is worthless IMO.

It seems to me that having 460Lm for 35.00, even a clumsy arrangement may be the proof I need to abandon the dim yellow. If I get convinced, I'll stop posting here.

By the way, I appreciate your taking the time to reply ...to yellow, LukeA, blasterman everyone, is appreciated. I now have a better understanding of heat-sinking and I didn't know anything about it before. So thanks.


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## Yoda4561 (Jan 1, 2009)

Well don't stop posting  I do think you should start off with a cheap flashlight+ adapter setup, just to get a quick feel for what modern LEDs are putting out. Then once you get an idea of just how much and what kind of light they make you can work on a custom setup that's better suited to your needs.


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## dom (Jan 2, 2009)

Yes -no need to stop posting at all -i myself
had lost track of your original question is all 

The brightness of LEDs will blow you away as 
they did me when i first got some from Ktronik for my bike.

I had a 35W(i think) of spot/flood halogen on my bike and he made me Luxeon triple light -WOW -less power and WAY brighter.

Get yourself even a cheapo light as suggested and you won't be disappointed. 
Twofish Lockblock onto the bars for a trail.

Cheers
Dom


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## LightTracker (Jan 2, 2009)

Thanks for the encouragement keep posting. I enjoy discussing and I'm learning.... I noticed my avatar now says "enlightened" but I have much to learn.

I'd like to try the Deal Extreme 230Lm flashlight for 17.50 (to start out), but how do I make sure I get what's advertised?

One of the buyers said this: 

"This is a great light.... when Trust Fire puts the proper Q5 emitters in.... you get the full rated 230 lumens stated with good TrustFire 18650 3.7 V 2500mah batteries. The last three I ordered.... all three of them did NOT have Q5 emitters installed in them."

Have you guys had better luck in dealing with this company? Do you know anyone else who may have a 150-250 lumen light on the cheap?

Thanks!!


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## LukeA (Jan 2, 2009)

LightTracker said:


> Thanks for the encouragement keep posting. I enjoy discussing and I'm learning.... I noticed my avatar now says "enlightened" but I have much to learn.
> 
> I'd like to try the Deal Extreme 230Lm flashlight for 17.50 (to start out), but how do I make sure I get what's advertised?
> 
> ...



I have that exact one. It's a very good one. To make it work, you want 

1) the light
2) rechargeable 18650s
3) charger for said cells
4) (optional but recommended) case for cells when not in light

I own all of these items and am pleased with them.

Charger sku.6105 is also acceptable and has good reviews, but I don't own one.

If you're concerned about getting a P4 version instead of the Q5, page 3 of this thread is something you should read. (The rest of it is also worthwhile to readif you're interested in the light.)


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## LightTracker (Jan 2, 2009)

Looks like for 39.00 I can get my feet wet. Way cool to help put a list together, thanks LukeA! I read that thread found the cat pictures entertaining....

Is a P4 supposed to be an improvement? I think I'll go fort the factory light w/no mods starting out. The comments about the TR-801 sound fairly positive.

I think I'll try:
1) $19.98 TR-801 Cree Q5-WC 5-Mode 230Lm LED Flashlight
2) $10.49 18650 Lithium Battery 2400mAh 2-Pack
3) $8.44 Digital Li-Ion 18650 Battery Charger

Total w/shipping: *$38.92*


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## LightTracker (Jan 2, 2009)

I found a comparison of P4 and Q5.

Characteristics of emitted light are a bit different according to those photos. The Q5 looks a bit brighter, it definitely has a brighter hot-spot.

I also found this though in an MTB thread: "P4 driven with 470ma is as bright as a [email protected]"

I can't speak to the electronics, don't know those terms yet, but what I understand to this point is you get different characteristics and heat-sinking requirements when you vary input. Do manufacturers list the limits? I'm also not sure what the role of the chip is, though that thread LukeA links to above talks about swapping them.

What's a Flashaholic? Does this mean you've posted so many times, or you've gone bankrupt expanding your collection?

Cheers!


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## Christexan (Jan 6, 2009)

The Cree XR-E "Binning and Labeling" spec sheet shows their progression, the basic rule is they use a letter, followed by a number "2-5" typically (1 is confusing with l(L), so probably why they skip 1)... so a P2, P3...P4, Q2..5, R2...5, etc.. (R2 is the highest currently released)... they sometimes skip in their progression, based on advances that leapfrog a step or two, but that gives a basic intro (other brands use different nomenclatures, but same concepts). These steps are typically around a 5-10 lumen range (at 350mA, the base rating they always use (as do most mfgers). So at 350ma, a P4 is someting like 87-91 lm, a Q2 91-95, etc (those aren't accurate, just roughly from memory)... a Q4 is (was at the time) the first ever "100lm @350mA" typical commercial LED on the market. Cree XR-Es follow a fairly linear curve from 350mA to 1A output (at controlled temperatures, not in "real life"), ending roughly 2.2x brighter at 1A (1000mA). So to get a P4 from 87lm (at 350mA) to 100lm, is only a 13% increase, or 350*1.13=396mA. Again, this isn't perfect (it's not truly linear but a slightly declining curve), but it shows that the initial bin difference isn't a big deal (but results in more heat and power consumption for the same output, which is why everyone likes the highest bin available). 
Bottom line, if you are doing a 3-LED emitter, using 3 Q4 bin (easily available and not overpriced) emitters, and want 300 lumens, you can run that at 350ma and ANY aluminum housing (with a well made direct emitter to housing thermal path) big enough to contain the electronics, emitters, and lenses, will have enough mass and surface area to extract the heat under any reasonable conditions (350mA @ 3.2Vf (typical voltage per LED at that mA)*3 = 3.36 watts of heat to extract safely (actually it's only about 80% of that because the LED emits around 20% of the energy input in the form of light, so it's around 2.7 watts of "heat" to dissipate). 
Now if you want 400lm, you need to increase the lumen output 33%, so figure a 35-40% current increase to achieve that, which will also slighly increase your Vf... so now let's say 475mA @3.3Vf *3 = 4.7 watts of total power consumption (*0.8 = 3.76 watts of heat to dissipate)... this is still easy to extract if it's a bikelight in motion with any housing large enough to hold everything (and won't get TOO hot sitting still unless the ambient temp is hot as long as it's moved a little or some air is flowing). 

Where additional steps are needed for heatsinking is when people are running 3 emitters at 1A (or a multi-die LED emitter like the P7 or MC-E). 3XR-Es at 1A is roughly 1A*3.6Vf(typical)*3 = 10.8 watts (or 8.65 watts of heat)... at this point the LEDs are cooking if you can't keep the housing cool, so additional fins or other cooling methods are added. 
It's not an issue in a (well-designed) flashlight, because the battery tube alone adds tremendous surface area, and the hand holding it absorbs a lot of the heat as well (liquid cooling via blood circulation). But in a compact bikelight, it becomes a much bigger (smaller surface area) issue. 

Regarding the Wilma, the picture in the posting doesn't do it justice, the back of it is actually a finned "cone" of metal heatsinking housing, if you saw it from the side it would make more sense, there is a LOT of heatsinking behind the front housing. Hope that helps some!


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## LightTracker (Jan 6, 2009)

Christexan said:


> Hope that helps some!



Wow, if information were food I'd not go hungry for at least a week! I'm going to mull over this, look some things up, and absorb /digest what I can... then, no doubt, I'll ask more questions. Really, thanks!

I'm still not sure what a "flashaholic" is, though I suspect the description changes once you make a certain number of entries.

Cheers to all!


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## Oznog (Jan 7, 2009)

Well for worn applications, it's not just about how hot the LEDs get.

With a thermal connection to the case but not a lot of surface area, the case can get mighty hot. Who wants a light on their forehead you could fry an egg on? Plastic parts it comes in contact with may be softened too.

There could be some sort of outer protection ring of thermally insulating to protect you from the heat... but generally any attempt to do so makes the sink-to-air thermal resistance even worse.


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## kuksul08 (Jan 8, 2009)

blasterman said:


> Yeah....that made me chuckle. With equal absurd logic I could argue you should use Red LED's because they don't cause your pupils to contract under low light. Plus, you could walk up to people and say "I am Borg". If I see a hiker walking around in the woods at night with a blue/cyan LED I'll know who to blame at least.
> 
> You'd think by now we'd be done explaining that 'white is not a color, but a combination of colors'.




Hahahaha.... wow this had me laughing pretty good!


To help the OP, maybe you can build something similar to me. It's pretty simple and totally doable. It's basically a 2-led version of the light on www.bikeled.org, using cree xr-e R2 leds and ledil optics. They should fit well in 1" tubing which is easy to work with only a few hand tools.


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## LightTracker (Jan 8, 2009)

kuksul08 said:


> To help the OP, maybe you can build something similar to me. It's pretty simple and totally doable. It's basically a 2-led version of the light on www.bikeled.org, using cree xr-e R2 leds and ledil optics. They should fit well in 1" tubing which is easy to work with only a few hand tools.



Would it look something like this? (apologies for mangling this image)






Would heat sinking be accomplished by lengthening the tubes, by using fins... or, is it necessary? Like I said I don't have the math part down yet. But yes, in any case, I'd like to be involved in helping to think through the problem and build one just like yours or similar, maybe compare notes....

Thanks for your input and the suggested project!
LightTracker:thumbsupan


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## LightTracker (Jan 8, 2009)

Oznog said:


> Well for worn applications, it's not just about how hot the LEDs get.....There could be some sort of outer protection ring of thermally insulating to protect you from the heat... but generally any attempt to do so makes the sink-to-air thermal resistance even worse.



I've thought about that. Would you be willing to help think through the project problem suggested above by kuksul08?

Your input is appreciated!


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## kuksul08 (Jan 10, 2009)

LightTracker said:


> Would it look something like this? (apologies for mangling this image)
> 
> 
> 
> ...




Yes just like that. Except I don't even plan on including the mounting base, just velcro. If you read all over that site (there's a ton of good info), you will see he explains a little about heatsinking. Apparently it's good to have 3 square inches of exposed metal per watt of power. You could either add fins (like his copperhead project), or maybe even use 1x2" tubing for the rear of the light. There are many options.

Currently I'm waiting on parts from DX, it's going to be a couple weeks so the project is on hold until then, I have just made the enclosure:






http://i106.photobucket.com/albums/m267/kuksul08/pbvision.jpg


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## LukeA (Jan 11, 2009)

kuksul08 said:


> Yes just like that. Except I don't even plan on including the mounting base, just velcro. If you read all over that site (there's a ton of good info), you will see he explains a little about heatsinking. Apparently it's good to have 3 square inches of exposed metal per watt of power. You could either add fins (like his copperhead project), or maybe even use 1x2" tubing for the rear of the light. There are many options.
> 
> Currently I'm waiting on parts from DX, it's going to be a couple weeks so the project is on hold until then, I have just made the enclosure:
> 
> ...



Looks good. You should paint it or anodize it black for emissivity.



> In general, the duller and blacker a material is, the closer its emissivity is to 1 [the ideal]. The more reflective a material is, the lower its emissivity. Highly polished silver has an emissivity of about 0.02.


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## kuksul08 (Jan 11, 2009)

LukeA said:


> Looks good. You should paint it or anodize it black for emissivity.




Hmm interesting, and to think I was planning on using a buffing wheel to polish it to a mirror finish


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## Yoda4561 (Jan 11, 2009)

I don't think painting will do much good. While black is better, all else being equal, I think the insulating property of the paint will offset any cooling efficiency increase. Feel free to experiment though


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## LukeA (Jan 11, 2009)

Yoda4561 said:


> I don't think painting will do much good. While black is better, all else being equal, I think the insulating property of the paint will offset any cooling efficiency increase. Feel free to experiment though


I don't have to. *The Celsius to Fahrenheit conversions are very wrong*


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## Yoda4561 (Jan 11, 2009)

Wow, impressive. And with a thermocouple too, an IR thermometer might have thrown things off a bit since they don't like shiny surfaces. I wonder if the "flatness" makes more difference than the color. http://www.virtual-hideout.net/reviews/Thermalright_TRUE_Black_120/index.shtml These are basically two identical heatsinks, the only difference being one is black electroless nickel plated, and there's only a 1-3 C difference. .. And of course reading a bit further turns this up https://www.candlepowerforums.com/posts/1715962&postcount=26 which shows that the emissivity makes a much larger difference in the absence of active airflow. I'll need to try this with some of my passive heatsinks


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## LukeA (Jan 11, 2009)

Yoda4561 said:


> Wow, impressive. And with a thermocouple too, an IR thermometer might have thrown things off a bit since they don't like shiny surfaces.



Because the emissivity is so low that they can't get a reading.


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## uk_caver (Jan 11, 2009)

What would be the simplest way to make a small area of a metal case temporarily suitable for observation with an IR thermometer (if the metal case wasn't cosmetically important, so later removal operations didn't need to be immaculate)?


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## LightTracker (Jan 11, 2009)

I had no idea what emissivity means much less that it would matter so much in dissipating heat.

Question:
What if the case comes from a solid (maybe a casting) rather than several pieces joined together? 

Anyone know of a natural, flat black, 'cast-able' substance of good thermal conductivity that is durable and could also be formed to accommodate 2 XR-Es?

Has anyone manufactured an LED as part of a larger solid that's meant to conduct heat away?


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## LukeA (Jan 11, 2009)

LightTracker said:


> I had no idea what emissivity means much less that it would matter so much in dissipating heat.
> 
> Question:
> What if the case comes from a solid (maybe a casting) rather than several pieces joined together?
> ...



Aluminum coated with black spray paint?


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## LightTracker (Jan 11, 2009)

LukeA said:


> Aluminum coated with black spray paint?



May be a dumb question but is there something available like a graphite composite that can be shaped for a DIY project? 

Graphite apparently can have higher thermal conductivity (470 W/m*K) than even copper (which is 398). It weighs less than aluminum which is 247. See chart 

There's probably a space age material perfect for this, but not usable for DIY. On the other hand maybe there is something brilliant out there hasn't been considered yet... 

Aluminum and black paint is probably it. Just thought I'd ask

Cheers!


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## jtr1962 (Jan 11, 2009)

LightTracker said:


> I had no idea what emissivity means much less that it would matter so much in dissipating heat.


It doesn't matter that much. This is a myth which has taken on a life of its own on CPF. Only in the vacuum of space is emission by radiation the sole method of heat transfer. Heat sinks in air mostly operate by convection and conduction. The heat radiated away via emissivity is a fraction of a percent. The real reason black (or in practice any other color) anodized heat sinks work measurable better is because the anodizing process increases the surface area (similar in principal to adding more fins), not because of the increased emissivity. Black paint will make the heat sink worse, not better, due to the thermal barrier the paint provides.


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## uk_caver (Jan 11, 2009)

jtr1962 said:


> The real reason black (or in practice any other color) anodized heat sinks work measurable better is because the anodizing process increases the surface area (similar in principal to adding more fins), not because of the increased emissivity.


But isn't that increase in surface area/roughness only applicable to radiation, rather than convection?


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## jtr1962 (Jan 11, 2009)

uk_caver said:


> But isn't that increase in surface area/roughness only applicable to radiation, rather than convection?


No, conduction and convection work better with more surface area also. That's why a microprocessor heat sink with more closely-spaced fins works better than one with fewer widely-spaced ones.


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## saabluster (Jan 11, 2009)

jtr1962 said:


> It doesn't matter that much. This is a myth which has taken on a life of its own on CPF. Only in the vacuum of space is emission by radiation the sole method of heat transfer. Heat sinks in air mostly operate by convection and conduction. The heat radiated away via emissivity is a fraction of a percent. The real reason black (or in practice any other color) anodized heat sinks work measurable better is because the anodizing process increases the surface area (similar in principal to adding more fins), not because of the increased emissivity. Black paint will make the heat sink worse, not better, due to the thermal barrier the paint provides.


Granted I just came into this thread but I don't think anyone was saying emission was the sole method of heat transfer. If you are using the right paint it does not hurt the performance of a heatsink. It helps. Just curious if you have ever looked at Newbies work in depth? You might say I am a disciple of sorts of Newbie considering the amount of time I have spent reading his site learning(and I suggest everyone else here do the same). Yoda4561 in post 55 linked to one of his posts. Please go back and read his tests if you have not done so. The thing I appreciated about him was he wasn't an armchair flashlight enthusiast making assumptions based on what he thinks he remembers from science class as so many here do(this is not directed at you JTR). Of note too was his focus on the fundamentals of flashlight construction. You can of course find all his stuff here if you search for it but he has compiled it all at his website which has the information more organized.


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## uk_caver (Jan 11, 2009)

jtr1962 said:


> No, conduction and convection work better with more surface area also. That's why a microprocessor heat sink with more closely-spaced fins works better than one with fewer widely-spaced ones.


There's a pretty huge difference in scale between adding fins to a heatsink (or even grooving heatsink fins at millimetre scales) and roughening a surface at the microscopic level.

With sub-micron roughening, when it comes to convection, would that roughening not be more or less smoothed out by the boundary layer of air adhering to the surface?


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## Yoda4561 (Jan 11, 2009)

LightTracker said:


> ]
> 
> There's probably a space age material perfect for this, but not usable for DIY. On the other hand maybe there is something brilliant out there hasn't been considered yet...
> 
> ...





That space age material is called aluminum alloy  Heatpipes are also an option, but the difficulty in implementing them in LED applications has limited their use, and mounting the LED to a suitably sized aluminum slug works fine with less hassle.


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## LukeA (Jan 11, 2009)

jtr1962 said:


> No, conduction and convection work better with more surface area also. That's why a microprocessor heat sink with more closely-spaced fins works better than one with fewer widely-spaced ones.



Only to the point that the boundary layer impinges on airflow.


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## LukeA (Jan 11, 2009)

uk_caver said:


> What would be the simplest way to make a small area of a metal case temporarily suitable for observation with an IR thermometer (if the metal case wasn't cosmetically important, so later removal operations didn't need to be immaculate)?



candle soot


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## LightTracker (Jan 13, 2009)

Yoda4561 said:


> That space age material is called aluminum alloy  Heatpipes are also an option, but the difficulty in implementing them in LED applications has limited their use, and mounting the LED to a suitably sized aluminum slug works fine with less hassle.



What particular alloy is known to have the best properties? Is it suitable for casting? Again, not necessarily for DIY... I'm just curious. There are some elaborate machined housings I've seen (though I can't remember where to link to) but I'm curious is anyone using a casting?

Would something like this work? An aluminum casting shaped like a cup with a thick bottom and thin sides:







The gray line is supposed to indicate thickness, Maybe the sides would be thinner, maybe you could saw into the sides to increase surface area. Maybe there's a cup like this lying around? Maybe its not a casting, maybe machined from a solid?

Casting would naturally have a rougher surface and help slightly....

Any thoughts or ideas?

Cheers!


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## LightTracker (Jan 13, 2009)

Yes, even you can melt metal at home. Using this instruction book for just $7.95... Shows how to make a crucible furnace from a clay pot, it runs on ordinary charcoal can achieve heat necessary to melt aluminum in 10-15 minutes.

Just need a casting pattern and form. 

Hmm.... am I still on topic? Well, since its all in the interest of getting out from behind that dull orange glow... proving that its worthwhile to do, etc... seeking to compare, but do it myself, on the cheap... Its a stretch but I'm on topic if you look at it in just the right way!

Cheers!


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## LukeA (Jan 13, 2009)

Can casting give you sections as thin as those you can get from assembling extruded metal? If it can, then great. If it can't, then there are a few different options to get good thermal performance.


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## LightTracker (Jan 13, 2009)

LukeA said:


> Can casting give you sections as thin as those you can get from assembling extruded metal? If it can, then great. If it can't, then there are a few different options to get good thermal performance.



You can cast very small thin parts.

I suppose you could saw "fins" into the side something like this, maybe increase the surface area by 50%:






Any thoughts, ideas or suggestions? (I don't think spacing of saw cuts should be as close as I've drawn as it could weaken the housing.) 

Also, I'm just thinking out loud here, no9t planning on doing this necessarily just want to see what others may think... (I mean if you had your druthers...)

Cheers!


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## LightTracker (Jan 14, 2009)

This question applies if you'd like to find a cheap (DIY or not) LED alternative to what's now available for medium to high light output, say 500-1500Lm.....

Question: What is an ideal housing and mounting surface capable of adapting for bike/head/hand? (only thing not considered is underwater)

I've not ruled out anything discussed so far, I was just hoping to see what people would prefer exactly, if choice exists, else its compromise, right?

Cheers!


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## LightTracker (Jan 16, 2009)

saabluster said:


> ....Just curious if you have ever looked at Newbies work in depth? You might say I am a disciple of sorts of Newbie considering the amount of time I have spent reading his site learning(and I suggest everyone else here do the same). Yoda4561 in post 55 linked to one of his posts. Please go back and read his tests if you have not done so.... Of note too was his focus on the fundamentals of flashlight construction. You can of course find all his stuff.... he has compiled it all at his website which has the information more organized.



Hey saablsuter, I appreciate that link to Newbie's work. Being a true Newbie myself I don't think that title fits him. Anyway there's a wealth of useful information there, esp. if you want to understand the fundamentals, its becoming more clear, as I read of some of the work that's done, its possible to come up with a great design if you have the right knowledge.

Anyway, thanks, I do have some work cut out for me. I also found out my friend's brother J.D. is into building LEDs. He has shared a few links with me that may be worth checking out.

Cutter Electronics Products (4 LED unit w/ Lens for $60.00)
The LED Guy
Driver for 25.00

He has done it differently that what I described above. He went through about $200.00 in LEDs, drivers, etc. learning what not to do. I'm going to have lunch with him to find out what he's learned and I'll share in this thread.

Again, thanks for Newbie's link!

Cheers!
LightTRackerDan

Ps. I hope some others are interested in pursuing a joint project at least as far as the ideas go, I'm hoping to rough out a design for an inexpensive kick-*** light, and don't expect to know everything myself. My brain is only so big (somewhere between a pea and a grapefruit)


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## LightTracker (Jan 16, 2009)

I just wanted to toss out some of what I think are ideal features and if you would not mind helping me to throw out what would commonly be seen as "not doable" I would appreciate that.

Then I'm going to get off this thread for a while rather than risk talking to myself (the last 4 posts are all mine)....

1) Non-proprietary design (meaning its freely shared)
2) Lumen range of 500-1500 -- Higher is better
3) Heat sinking designed into housing/mount configuration
4) Focusable (is this even possible?)
5) Adaptable for bike, headlamp or hand
6) Electronics capable of adjusting for conditions
7) Dimming
8) Readily available parts
9) Don't have to take out a second mortgage to do it
10) Easily built once parts are acquired

Can anyone add to this list? If you do, don't hold back. Also, what should be removed because its just plain dumb? (Don't worry about hurting my feelings). Also, I know this could be drifting from the topic and may need to be moved somewhere else, and that's fine. Just let me know....

Be bright!
LightTrackerDan


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## Resqueline (Jan 17, 2009)

As for the OT, using Cree's or Rebels with 100 lm/W gives you around 5 times more light than a halogen of the same wattage, but then it's a question of your needs and funds if it's worth it.
Being a noob here (but not to electronics etc.) I must say I've found it very hard to understand my options when it comes to refitting my 4D Mag with LED..
LightTracker: you have set up a nice list, aiming high (500lm=5W-LED=25W-halogen), but as you suggest it might be slightly O/T, I feel it deserves it's own thread. This one's already gotten quite long as it is.
A while back I tried casting something with an aluminum alloy btw., using a propane torch, but I guess it didn't get hot enough because the melt seemed to be too viscous for my application.


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## LightTracker (Jan 19, 2009)

Resqueline said:


> As for the OT, using Cree's or Rebels with 100 lm/W gives you around 5 times more light than a halogen of the same wattage, but then it's a question of your needs and funds if it's worth it.
> Being a noob here (but not to electronics etc.) I must say I've found it very hard to understand my options when it comes to refitting my 4D Mag with LED..
> LightTracker: you have set up a nice list, aiming high (500lm=5W-LED=25W-halogen), but as you suggest it might be slightly O/T, I feel it deserves it's own thread. This one's already gotten quite long as it is.
> A while back I tried casting something with an aluminum alloy btw., using a propane torch, but I guess it didn't get hot enough because the melt seemed to be too viscous for my application.



Resquiline,
Thanks for the tip on starting a different thread. I don't know what to call it, but I think you're right...

A magazine article from Dec. 2007 says you can upgrade your MagLite (4,5, or 6 D cell) to 600 lumens with a drop in unit. See TerraLUX Upgrade

Image of MagLite upgrade unit: 





Maybe CPF Market Place is still selling these for $80.00?

I'm glad you approve of my wish list. By the way, I saw an LED MagLite at Costco that focuses, so I now know that can be done with a single LED. I'm not convinced it can't be done with multiple LEDs, I just haven't seen it done yet. To be on Topic for a change, here is a Costco article about that MagLite that says, "LEDs don’t shine farther than halogen bulbs, but they are brighter at a shorter distance." Hmm... you'd expect by focusing you could get a spot beam, and throw farther. Maybe that's not what you get exactly. I do think LED is still lacking. Its NOT an improvement over say, even a candle, in some respects. 

Also along the line of "LED compared to Halogen"... A 100 watt incandescent bulb is relatively cheap to buy (and operate), yet it produces 1750 lumens of actual output! The closest portable light that I've seen in LED costs around $1100.00 to do that. The rub with incandescent is efficiency, but for something invented in 1800 its still amazing! I'm waiting to see an LED light that can truly rival HID (like Polarion) or even my old 32 watt halogen system (that you can pick up used for twenty bucks)... for such things as throw, focus-ability, low cost or the fact that you won't need an engineering degree to understand it. The characteristics of LED are somehow off, it looks like a welding arc or a camera flash, lacking somehow in character or "feel" (IMHO) And all that being true, I still look forward to seeing what happens with LED, theoretically it could become all that incandescent was, and more.

Cheers!


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## LightTracker (Jan 19, 2009)

*Concern About Heat Dissipation w/LED*

This is from someone who will help me design a 600-700 lumen LED flashlight. I told him I'm concerned about dissipating heat:

"There's a [lot of] worry about heat buildup. It's more of a problem with older LED's and overdriving LED's. If you go to Cree's website and look at the XR-E literature you'll see that max. junction temperature is around 150C [or 300F]. There's also a graph that shows luminous flux as a function of junction temperature. At 60C [or 140F] you're still at 90% of max. luminous flux. I think the [concern] is maintaining max. flux."

From what I found at CREE's website (and by reading about luminous flux in general) is that newer products have largely dealt with the issue. And as long as you roughly go by the manufacturer's guidelines you'll be okay, i.e. there is no need to measure junction temperature unless you depart significantly from what's recommended, including (I think) for solders.

I found this at CREE about Reflow solder:

*Reflow Soldering Characteristics In testing:
*
Cree has found XLamp XR-E LEDs to be compatible with JEDEC J-STD-020C, using the parameters listed below. As a general guideline, Cree recommends that users follow the recommended soldering profile provided by the manufacturer of solder paste used. Note that this general guideline may not apply to all PCB designs and configurations of reflow soldering equipment. 

Somebody shared the data sheet earlier, but here it is again: 
CREE XLamp XR-E Data Sheet

Cheers!


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