Thanks for the reply! I think this might me my problem, I said 600v but thats all my volt meter goes up to[:-] you cans ee the voltage rise as it charges, it hits the 600v limit and JUST afterwards it self discharges, what I think is happeneing is the DC volts are so high it jumps across the thyristor internally, that dicharges the high volt capacitor and it makes the spark at the plug. I did not have the PIC board connected so there was no prob there. I'll change the 4.7nF for a 4.7uF tonight and try that. I was running off a 6v battery.

My home made coil did not work either, you can hear it sparking internally. I'm going to wind another with an insulation layer between each run of secondary.

Cheers,
Rich