This is a regulated high voltage boost converter, it can output up to 600V with loads not exceeding 1Meg ohm as is typical in driving Geiger-Muller tubes, it can run at down to 6V supply voltage without any problems, typical quiescent current is 120mA with 60% to 70% conversion efficiency.
This circuit doesn't work very well in everycircuit due to the narrow current duty cycle required however it works perfectly well in real life, for the switching transistor I used FDP7N60NZ, for the diode FR107 and a LM319 dual comparator, the transistor right on the output isn't needed that's just so it works as a comparator rather than an op-amp in everycircuit.
Switch input duty must exceed 70% to minimize power dissipation, optimal duty is around 95% at 10kHz.
