Ben, I actually have the circuit setup with the PWM (same one I gave you) triggering the transistor. The h11d1 is an opto isolator, which isnt necessary, but you can use one if you like. If you are going to Jaycar for the parts you will have to get the h11d3, which is the same except rated for 50v instead of 300.

I only noticed the self triggering when I hooked in the solenoid off the HV coil and my PWM input wasnt connected. Mind you I can get 4 lights lit to useable brightness on 24v @ 100-150ma with the PWM in use.

I only posted the above circuit because I found it interesting. The self oscillations only start when the second coil is placed in series with the HV output, and the lights are lit off one wire, which terminates at the last globe, i.e it doesnt hook back into the circuit. I never had any problems with Aromaz circuit, except I couldnt get the lights very bright.

Ill come around sometime and show you how to hookup that PWM if you like