Photo flash capacitors

doubleroger · May 31, 2009

I just found a 4kW photo flash unit down the street (not the lamp, just the "power pack" part), and dismantled it to get some spare parts, as it had 4 beautiful backlighted swiches, filtered IEC etc.

Inside of it were 48 big (like 10 cms high) 2200uF / 360V caps, tied altogether forming a big 52800uF / 720V cap.
They have been rebranded by Elinca, the flash manufacturer (aka elinchrom) and read "elinca, photo, 220/360V, ce p".

I imagine those caps are supposed to be used for isolated high energy discharges, but how useful could they be for some PSU filtering, maybe in power amps? (which would be really nice considering that I found a 500VA 4x37VAC transformer just last week

)
Maybe in some other applications?

peterc · Jun 1, 2009

I have used these in valve amp supplies before, no problems.

Another place to find these is at the local photo printing shop. There is one in every disposable camera, ask them for the disposables they have taken the film out of.

Peter

sahib · Jun 1, 2009

There is no reason why you should not form a low pass filter with a suitable inductor. In fact I removed three of them including the inductors from a 3 phase photographic equipment and they are waiting to be used for something at some point.

stickjam · Jun 1, 2009

My first thought is to watch out for the startup current - those big caps will look to your transformer and rectifiers like a short circuit for much longer than smaller caps. On second thought, I wonder if the soft-start of a warming up rectifier tube would help alleviate this?

Oh yeah--pay attention to the bleeder resistor to discharge on power-off. Nothing like having 300V B+ still be live after a unit's been unplugged for a week.

;D

Back in the day, I was into TTL digital circuits like crazy. I built a lot of monstrous creations that needed 5V regulated supplies with tons of current. I had bunch of these giant 1/3-farad computer grade caps. I put a few in a LM323-based linear supply--the current draw at turn-on time made the transformer emit an impressive noise: imagine a 1-meter diameter china cymbal. ;D

doubleroger · Jun 1, 2009

stickjam said:
My first thought is to watch out for the startup current - those big caps will look to your transformer and rectifiers like a short circuit for much longer than smaller caps. On second thought, I wonder if the soft-start of a warming up rectifier tube would help alleviate this?

That was my main concern about using it with high voltage. Not sure 2200uF is not a bit overkill....
Is there anything special I should do if I wanted to use it, say, for filtering B+ type DC in a simple linear HV PSU (with a 10A diode bridge)? I'm afraid I could kill the transfo before I kill the ripple. ;D

Another question: If I were to use them in a solid state amp, would the relatively low polarization voltage across the caps(80VDC against the 360VDC max they are rated for) become a problem in the long run (aging or something alike) ?

Those are not the type of caps one finds in small disposable cameras, they are bigger than the cameras themselves. They must weight 500 grams each.

This is just curiosity by the way, I'm not doing anything for the moment, just thinking out loud "what could I do with that stuff on the shelves".

Thanks for your answers!

Photo flash capacitors

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Photo flash capacitors

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