It is easy to see that building a simple
high voltage power supply with parts just laying around is not
that difficult. The goal was to accomplish the task of producing
a medium current
high voltage spark gap power supply. The simplicity comes with a
price. This kind of circuit has no control over oscillating
frequency or pulse width. The oscillator is free running.
The flyback joule thief circuit. The high
voltage feedback is what keeps an LED blinking when a battery
appears "dead" I reasoned that it should be easy to build a much
more
powerful version by just up sizing the components. So lets take
a look at the basic circuit diagram of a "joule thief".
So all I needed was a much
bigger coil. I pulled out of an old UPS Backup. I also
needed a 1K ohm resistor that could handle at lease 25 watts.
Instead of a battery. I used an old 24 volts DC dell laptop
power supply for input power. For my NPN transistor.
I just used any generic low frequency general switching NPN
power transistor I had laying around. You simply need to look up
the transistor and make sure what ever your
DC power supply is. That the NPN transistor you choose can
handle what ever voltage your salvaged DC power supply is rated
for. The feedback is connected in parallel with
the primary winding of an old CRT high voltage flyback
transformer I was able to use. The high voltage side of
the flyback is what feeds this big noisy spark gap.