I suggested the 555 not for timing purposes, but as an oscillator to charge a large capacitor to 500v. I want to use a 12v supply voltage then bump it up to 300v. I am using a disposable camera unit now with a diff capacitor(bigger) soldered in place of the original. This works but I would like to build my own power supply. Thats what I was asking for, a circuit similar to the photoflash charger. Basically I just need a 12v to 300v power supply. My capacitor bank will be (3) 400uf 500v capacitors wired in parallel. So I am looking for a circuit that will charge them relatively quickly.