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Charging camera flash capacitors from mains supply Answered

Hi everyone,
I have a quick question about charging some capacitors.  I'm trying to make a very simple ignition system using capacitors from disposable camera flash circuits.  I'm planning on using maybe 5 or so.  They are rated at 330V and 120uF.  If I were to hook them up in parallel, so that i have a total of ~600uF, could I use a full-wave bridge recifier diode to turn the AC into DC and simply charge it like that without anything else in the circuit.  I don't know how to explain this very well so I attatched a schematic so you can see what I'm talking about.  Any help is much appreciated..

P.S. Ignore the fact that the full-wave rectifier looks messed up, Circuitlab.com doesn't have a f-w r symbol. 
Thanks again!


Josehf Murchison

5 years ago

should be no problum as long as you put a over load resistor in parallel with the caps.

BCSTechieJosehf Murchison

Reply 5 years ago

What value resistor should that be? Is it dependant on the capacitor values? I also read somewhere that it would be good to have some type of load in series with the capacitors to limit the in rush current so that it wouldn't damage the rectifier...Would this be necessary? Thanks for the reply!

Josehf MurchisonBCSTechie

Reply 5 years ago

Over load resistor should be about 65 megohm 1 watt in parallel with the caps.
Current limitting loading resistor about 330 ohm 5 watt from rectifier to caps +.
Not sure of your service voltage if it is 220 volts double ohms and watts.
The over load resistor will drain the caps and make them safe when not in use also.
Remeber when rectifying service 110 AC becomes 180 DC
and 220 becomes about 360.