Posted: Tue Nov 13, 2007 2:41 pm
So I honestly haven't played with capacitors much. For a 100 volt cap, do you need a 100 volt source to charge it all the way, or can you use something lower voltage that will just take longer?
You need a 100V source to charge a cap to 100V. But, the source doesn't have to be continous, and indeed it usually isn't.paaiyan wrote:So I honestly haven't played with capacitors much. For a 100 volt cap, do you need a 100 volt source to charge it all the way, or can you use something lower voltage that will just take longer?
The typical photoflash board from a disposable camera converts 1.5V to ~300V pulses. The pulse duty cycle is usually pretty small, it is "off" for a lot longer than it is "on". IIRC, the photoflash boards cycle at 2KHz to 20KHz (or more) and have a duty cycle of perhaps 10%.
A diode is usually wired in series with the cap so the supply can charge the cap when the supply is "on" but the cap does not push current back into the supply when the supply is in the "off" part of the cycle.