# Help on tapping 300V DC out from 12-220V power Inverter



## ma_sha1 (Mar 26, 2011)

To build a 260W UHP short arc spotlight, I need to feed the ballast 300-350V DC.

I am trying to to tap the High DC out from my 12V DC-220V AC power inverter.
rated 350W. 

Here is a shot of the Power Inverter opened up & you can see the Capacitor with 
450V written on it. 

Where do I solder to get the 300-350 DC out of it? Is it possible to tap it from the top side or do I need to take the whole thing out & try to find the 12V DC from the under side?

Some kind of drawing would be greatly appreciated! I am a noob about circuits. 

Thanks for helping!


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## 45/70 (Mar 26, 2011)

*Re: Help on tapping 450V DC out from 12-220V power Inverter*

The "450V" on the cap is a _rating_ not a voltage that is present in the cap. It just means that the cap is rated at up to 450 Volts. There is no voltage higher than 220 Volt in your power supply.

*Edit *to add that for your PS to even have 220 Volts, the mains suppling it have to be 220 Volts. If your PS is hooked up to 110 Volts, then that is the highest voltage that is available.

Dave


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## 45/70 (Mar 26, 2011)

*Re: Help on tapping 450V DC out from 12-220V power Inverter*

Eh, on second, thought your refering to an inverter, not a power supply. In that case the highest voltage available is ~ 220 Volts.

Dave


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## ma_sha1 (Mar 26, 2011)

*Re: Help on tapping 450V DC out from 12-220V power Inverter*

Thanks, but this has been done before.
http://www.candlepowerforums.com/vb/showthread.php?254557-Cyclops-Thor-15MCP-to-120-Watt-UHP

Unfortunately, he didn't post details on how he tapped 300V DC out of the inverter.
For my Power Inverter,
The input is 12V DC.
The output is 220AC, 350W.

There is another guy who did this but his posts were lost. & he told me just find the Capacitor & tap the DC. maybe not 450V but it's 300V-350V or so.

The invertor works by first make 300V or so DC from the 12V input, then chop it up & down convert to 220V AC,

so, yes, there is higher than 220V in DC form on this board somewhere, just need to fin it


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## Mr Happy (Mar 26, 2011)

*Re: Help on tapping 450V DC out from 12-220V power Inverter*

If you are a "noob about circuits" it is highly recommended that you don't try to mess with high voltage, high power circuits as a learning exercise. You could kill yourself. Really, no kidding.

Please, put the lid back on and leave it alone.


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## BoarHunter (Mar 26, 2011)

*Re: Help on tapping 450V DC out from 12-220V power Inverter*

Please don't try to destroy the short but eventfull career of a potential Darwin's Award candidate !


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## ma_sha1 (Mar 26, 2011)

*Re: Help on tapping 450V DC out from 12-220V power Inverter*

Thanks Guys 

I am not good at circuit but I am pretty good with electricity, don't worry.
Plus, the power source is from a portable battery pack, about half of the energy of a Car battery,
not from the wall outlet. the volt is high but not as much punch behind it as the wall outlet.

I am extremely careful, but I need to do this. 

So, still need some help from experts on where to tap for 300V DC


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## Mr Happy (Mar 26, 2011)

*Re: Help on tapping 450V DC out from 12-220V power Inverter*

The danger is from that 450 V capacitor you are looking at. When charged, that contains easily enough energy to kill you.

If you knew enough to safely attempt what you are doing, you would not need to be asking here. You would know how to safely discharge capacitors with a suitable resistor, how to follow a circuit and how to trace voltages with a meter.

Given your current level of knowledge, you really should not attempt this.

Bear in mind that an electric shock with as little as 50 joules could kill you, and a single AA cell contains about 10000 joules. That is 20x more energy than is needed to end your life. Your comments about what might be dangerous are very naive.


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## billcushman (Mar 26, 2011)

*Re: Help on tapping 450V DC out from 12-220V power Inverter*

Please follow the recommendations you have been given about safety. High voltages can easily deliver "The fatal current" as Tektronix used to describe it. The fatal current is relatively low. It stops the heart and you are dead. Higher currents burn you and knock you away. If you don't already know these things, you should not be attempting your project. Please be safe.


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## Russel (Mar 27, 2011)

*Re: Help on tapping 450V DC out from 12-220V power Inverter*



ma_sha1 said:


> [...]Plus, the power source is from a portable battery pack, about half of the energy of a Car battery,
> not from the wall outlet.[...]


 
A common 9V battery is enough to kill. Half the energy of a car battery is far more than enough! I agree with Mr Happ and Billcushman, you shouldn't attempt tapping power from inside of an inverter!


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## mvyrmnd (Mar 27, 2011)

Rather than modify an existing device, you could get a transformer to step 220v AC up to 700v then use a bridge rectifier to bring that back to 350v DC. 

If you were crazy enough, you could build it yourself, but as it has already been said, it would probably result in natural selection.

Find an electronics guru to build you a custom power supply.


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## MikeAusC (Mar 27, 2011)

*Re: Help on tapping 450V DC out from 12-220V power Inverter*



ma_sha1 said:


> Thanks Guys
> 
> I am not good at circuit but I am pretty good with electricity, don't worry.
> Plus, the power source is from a portable battery pack, about half of the energy of a Car battery,
> not from the wall outlet. the volt is high but not as much punch behind it as the wall outlet.


 
This is attitude will kill someone very quickly - 300 volts DC will kill much faster than 110 volts AC.


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## MikeAusC (Mar 27, 2011)

*Re: Help on tapping 450V DC out from 12-220V power Inverter*



45/70 said:


> Eh, on second, thought your refering to an inverter, not a power supply. In that case the highest voltage available is ~ 220 Volts.
> 
> Dave


 
No, 220 volts AC means a peak voltage of over 300 volts, so the capacitor will have well over 220 volts on it.


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## HKJ (Mar 27, 2011)

*Re: Help on tapping 450V DC out from 12-220V power Inverter*



ma_sha1 said:


> Here is a shot of the Power Inverter opened up & you can see the Capacitor with
> 450V written on it.



That capacitor is probably the place to find the high DC voltage. It looks like for diodes that is standing next to it, you might also be able to find the voltage there. Try following the traces from the capacitor to the diodes.

If you short anything, you will probably blow the inverter and touching the wrong places will give you a very nasty jolt! (It might also kill you, especially if the current run through you heart and you have a weak heart).


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## saeckereier (Mar 27, 2011)

*Re: Help on tapping 450V DC out from 12-220V power Inverter*

The 9V story was interesting.

If you get shocked you should know that you should call an ambulance and get to a hospital to be monitored. Electrical shocks can cause small arrythmias that can lead to cardiac arrest up to 48h after the incident so proper monitoring is critical in that period.


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## ma_sha1 (Mar 27, 2011)

*Re: Help on tapping 450V DC out from 12-220V power Inverter*

Thanks for all the concerns, guys. The 9V story is interesting, didn't know breaking the skin 
make such a big difference, so going forward, we should never play with electricity with a cut & band-aid on. 

With the skin on, electricity travels along the skin, so 110 shock rarely kill people unless one touch the wire with palm & close on the wire due to muscle contraction.

Some electricians in Asia countries test 220V AC wires with bare hand some times, the rule is always test with back of the hand, the shock will bounce the hand away. Never touch with palm, as muscle contraction will cause grabbing the wire & won't let go 

I am sure most of you have felt the jolt from 110V AC some time during your life?
DC Volt risk is rated roughly as 1/3 of AC risk, so 330V DC is about 110V AC in risk, which is lower risk than 220V AC. But still, I am not under estimating the risk, I'll be extremely careful.


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## Mr Happy (Mar 27, 2011)

*Re: Help on tapping 450V DC out from 12-220V power Inverter*



ma_sha1 said:


> DC Volt risk is rated roughly as 1/3 of AC risk, so 330V DC is about 110V AC in risk


Where are you getting this nonsense from?

As has been pointed out any voltage high enough to disturb your heart rhythm is dangerous, potentially lethal. That includes 110 V AC.

Yes, many of us have been jolted by the mains, even 240 V, in our lives. That does not mean 240 V is safe, it just means we have been lucky.


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## ma_sha1 (Mar 27, 2011)

*Re: Help on tapping 450V DC out from 12-220V power Inverter*

I never said it's safe. It's relative risk info. I found by reading, but regardless, we are getting off topics here.

*OK, moving right along, I found the Hi DC Volts I was looking for *

I connected My volt meter black probe to the negative of the 12C in. Connected DC to 12V supply.Wear gloves in both hands & only held the red meter probe to look for the volts alone side of the capacitor





This pic. shows blow-up view of the 4 rectifier diodes, the leads coming off the top measured positive DV volts.The two on the side, measured 145 DC volts. *The two in the middle*, which appears to be connected on the board together, *measured the same 290 DC Volts.
* 
Now, I think I'll solder a wire to the two legs in the middle together (Increase current handling on the diode legs by 2x) to tap the 290V +. 







*My Only question remaining:*
 *
Should I be OK to use the 12V Neg Input as the "-" for my planned 290V DC outlet?
Or do I have to gain access to the "-" underside of the two middle diodes to use as "-"?
*
Obviously, the 12V input is much easier to access & by pass lots of circuit trace which increase current handling & reliability. 

Thanks


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## HKJ (Mar 27, 2011)

*Re: Help on tapping 450V DC out from 12-220V power Inverter*



ma_sha1 said:


> *My Only question remaining:*
> *
> Should I be OK to use the 12V Neg Input as the "-" for my planned 290V DC outlet?
> Or do I have to gain access to the "-" underside of the two middle diodes to use as "-"?
> ...



I do not know the schematic of the inverter, but I would suggest that you search some more for the minus. Just because the meter shows some voltage does not mean there is a direct connection. It is probably present on the downside of the two other diodes (D3, D7).


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## 45/70 (Mar 27, 2011)

*Re: Help on tapping 450V DC out from 12-220V power Inverter*



MikeAusC said:


> No, 220 volts AC means a peak voltage of over 300 volts, so the capacitor will have well over 220 volts on it.



I hadn't taken that into consideration. I always think in RMS voltage for some reason, when it comes to AC I guess.



Mr Happy said:


> If you knew enough to safely attempt what you are doing, you would not need to be asking here.


 
This is also why I probably shouldn't have posted in this thread!

Carry on ma_sha1. Do be careful though.

Dave


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## VegasF6 (Mar 27, 2011)

*Re: Help on tapping 450V DC out from 12-220V power Inverter*



ma_sha1 said:


> Thanks for all the concerns, guys. The 9V story is interesting, didn't know breaking the skin
> make such a big difference, so going forward, we should never play with electricity with a cut & band-aid on.
> 
> With the skin on, electricity travels along the skin, so 110 shock rarely kill people unless one touch the wire with palm & close on the wire due to muscle contraction.
> ...


 
That's doing it old school yo! Hah. Don't forget to always keep the other hand in your pocket or behind your back. At least, that's what the old timers have told me. Somehow, they were still alive to tell me this. You know, the guys that can't be bothered to shut off 480V while they hookup a circuit cuz it would slow production.

Oh P.S. I am not so sure those latex gloves are affording you anything other than a false sense of safety. I am not gonna harp on it or anything, just want to point it out.


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## italianboy (Mar 27, 2011)

*Re: Help on tapping 450V DC out from 12-220V power Inverter*

You could just access the other side of the board and solder the two wires for high voltage DC in parallel to the two leads of the 450V-rated capacitor. Be sure not to short them to the outer aluminum shell!


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## ma_sha1 (Mar 27, 2011)

*Re: Help on tapping 450V DC out from 12-220V power Inverter*

The back is not easily accessible as 5 resistors are thermo glued to the frame.

I measure the resistance between the - of the rectifier and - of the 12v in, it's Zero.
So I think it's the same to use either one.


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## MikeAusC (Mar 27, 2011)

*Re: Help on tapping 450V DC out from 12-220V power Inverter*



saeckereier said:


> If you get shocked you should know that you should call an ambulance and get to a hospital to be monitored. Electrical shocks can cause small arrythmias that can lead to cardiac arrest up to 48h after the incident so proper monitoring is critical in that period.



Unfortunately I can verify the seriousness of that recommendation - sadly a colleague of mine died that way many years ago.


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## MikeAusC (Mar 27, 2011)

*Re: Help on tapping 450V DC out from 12-220V power Inverter*



ma_sha1 said:


> . . . . Some electricians in Asia countries test 220V AC wires with bare hand some times . . .


 
Some people play Russian Roulette and live . . . . but there's no way I would suggest people doing that either !!!


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## saeckereier (Mar 27, 2011)

*Re: Help on tapping 450V DC out from 12-220V power Inverter*



MikeAusC said:


> Unfortunately I can verify the seriousness of that recommendation - sadly a colleague of mine died that way many years ago.


 
Sorry to ask, but is this something you witnessed first hand? (not the shock but the consequences) I have heard some reports of this and I have been taught this in training but so far I only heard third hand accounts.


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## MikeAusC (Mar 27, 2011)

*Re: Help on tapping 450V DC out from 12-220V power Inverter*



saeckereier said:


> Sorry to ask, but is this something you witnessed first hand? (not the shock but the consequences) I have heard some reports of this and I have been taught this in training but so far I only heard third hand accounts.


 
No witnessing. He received an electric shock from 240 volts which threw him, while working on a washing machine. Went to hospital and was discharged. Went to work the next day. Died suddenly the following day.


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## saeckereier (Mar 27, 2011)

*Re: Help on tapping 450V DC out from 12-220V power Inverter*

What I meant was this is not some story someone told you but you knew this colleague and know that the accounts are legit?


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## ma_sha1 (Mar 27, 2011)

*Re: Help on tapping 450V DC out from 12-220V power Inverter*

OK, I decided to wire the Neg. to the "-" end of the rectifier instead of 12v "-" in. 
I cut the AC out wires & re-wired to the 300V rectifier tapping, this way, I can plug in a beefy AC cord for the 300V DC, so it's more safe. 

There are total of 7 identical looking square power resistors & 6 of them were heat sinked to the wall, for some reason one is not. I don't know if that's some kind of negligence? As they all look identical. So I decided to heatsink it to the wall with a copper pad, as I'll be driving it pretty hard & don't want to risk one of them become the weakest link.







Biola, it's a success! I actually got a few more volts wiring to the rectifier neg. 
Thanks very much for all the help!


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## BoarHunter (Mar 28, 2011)

*Re: Help on tapping 450V DC out from 12-220V power Inverter*



Mr Happy said:


> Where are you getting this nonsense from?
> 
> As has been pointed out any voltage high enough to disturb your heart rhythm is dangerous, potentially lethal. That includes 110 V AC.
> 
> Yes, many of us have been jolted by the mains, even 240 V, in our lives. That does not mean 240 V is safe, it just means we have been lucky.



This non sense comes from the epic argument between T Edison promoting its DC power distribution system to N Tesla promoting AC !

Note that the reason why the US did not upgrade to 220-240 AC in the fifties was also because of the safety argument.

In the EU, to reduce the risk, distribution has been done in 2 X 220 AC and 3 X 220 AC with the neutral grounded. As accidental contact is usualy between ground and phase, you get 110 and 127 respectively.
In fact it started in Germany. It allowed almost a doubling of the current carrying capacity without changing the wirings.
Better protection mechanism (differential breakers) have allowed to go 3 X 380 AC, the 220 now being between phase.

You can survive a 220 electric shock as I experienced it at age 17 while tuning a tube radio but you learn to be extremely cautious. And yes, always the left hand in the pocket, proper rubber sole, even when I use my electric razor !


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## HKJ (Mar 28, 2011)

*Re: Help on tapping 450V DC out from 12-220V power Inverter*



BoarHunter said:


> In the EU, to reduce the risk, distribution has been done in 2 X 220 AC and 3 X 220 AC with the neutral grounded. As accidental contact is usualy between ground and phase, you get 110 and 127 respectively.



No, around there we have 230 VAC from earth and 400 VAC between phases in a 3 phase system. Ordinary household stuff uses the 230 VAC.


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## BoarHunter (Mar 28, 2011)

*Re: Help on tapping 450V DC out from 12-220V power Inverter*



HKJ said:


> No, around there we have 230 VAC from earth and 400 VAC between phases in a 3 phase system. Ordinary household stuff uses the 230 VAC.


 
You didn't read my full post ! I said that after this first change (completed in the sixties), we migrated to 220 phase to neutral,with 380 between phase (from a 3 X 220 AC to 3X 380AC). No change for regular lighting and household appliances but big change in the industry as motors ahd to be changed.
As there is always a few percent tolerance, a few year ago, the old upper limit became the standard average that is 230 AC with 3 X 400 AC distribution.

Copper is expensive, so without changing the wiring, you carry more power and also EU harmonisation because of the power grid covering all of Europe. 
And Germany needs the nuclear electricity they frown upon, from France


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## Russel (Mar 28, 2011)

*Re: Help on tapping 450V DC out from 12-220V power Inverter*



BoarHunter said:


> [...]You can survive a 220 electric shock as I experienced it at age 17 while tuning a tube radio but you learn to be extremely cautious. [...]


 
The point is that electricity can kill!


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## Walterk (Apr 2, 2011)

*Re: Help on tapping 450V DC out from 12-220V power Inverter*

I understood what you where doing here.
Now, at second reading I understand why you want the 300V. 

What will runtimes be with 300W ...?


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## ma_sha1 (Apr 3, 2011)

*Re: Help on tapping 450V DC out from 12-220V power Inverter*

Battery is 20AH Lifepo4 e-bike battery. 13.3V
300W pulled from 13.3V battery = 22.5 Amp. It'll run close to 1hr.


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## HooNz (Apr 3, 2011)

Hi all you Experts on safety , one should be aware that 220/240/110 ac is the RMS or equivalent DC voltage of said things , i am happy to read all the safety concerns of these dangerous voltages mentioned , as i would have HaTed to have been touching something on the peak of a sine-wave which would have been 220vac rms x 1.414=311v , 240vac [email protected] or 110vac [email protected] but only on those sneaky peaks! .
To op , good work there , i am glad that you did not use the dc common earth/rail as quite a-lot these days are separate due to extra safety concerns.

http://www.animations.physics.unsw.edu.au/jw/power.html

There is a old Indian saying that goes like this .
Those that eat dry crackers in bed Get crumby sleep .


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## Walterk (Apr 3, 2011)

HooNz said:


> Hi all you Experts on safety , one should be aware that 220/240/110 ac is the RMS or equivalent DC voltage of said things , i am happy to read all the safety concerns of these dangerous voltages mentioned , as i would have HaTed to have been touching something on the peak of a sine-wave which would have been 220vac rms x 1.414=311v , 240vac [email protected] or 110vac [email protected] but only on those sneaky peaks! .
> To op , good work there , i am glad that you did not use the dc common earth/rail as quite a-lot these days are separate due to extra safety concerns.



Thanks for the clarification.... I think....to put it in surfing language; 

Do you mean they all pose similar danger as they all share same wave heights at moments?


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## HooNz (Apr 3, 2011)

Exactly  , moments in time , generally in Hertz or cycles per second , an example is if one froze time at the exact peak of the wave with 340v(240vac) measured on the multimeter one could Safely poke your finger on it and NOT receive a shock , as at that time there in no current flowing at all (water volume) but there is still pressure (volts) but for 60hz or 50hz line frequency here it is to fast , on the rise just before the peak or just after the peak is really where the dangerous to biological things is as for people , it is suggested that just 50ua (at 240vac) across the chest can stop the engine of the hydraulic system , so just around the peak of the wave is 340v not 240v.

And of course the opposite is valid in frozen state at the 0 crossing point with all current and no voltage , sneaky peaks.

Another peak is winter , safely walk on thick ice in relative terms , the trough or 0 crossing point is just before summer :naughty: , its all Waves , even earth @ approximately 8hz .

But the main underlying source is "Do not poke finger In" :wave:


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