Came across this circuit to be used as a dual coil ignition coil driver recently and tried building it. However, despite all efforts, I can't get it to work:
If you read the description, you'll see that the included line voltage doubler is required if the circuit is to be operated from 120 v line. Therefore, I am using the doubler also.
Here's all I can get from the circuit. I use between a 25 and 60 watt incandescent in series with the 120 v input to the doubler for protection of the circuit. When I plug in the circuit, I hear no sparks nor is there any hum of the included ignition coil. Sometimes the 60 watt bulb will light brightly as the circuit is plugged in; othertimes the bulb does not light at all. Adjusting the variable resistor has no effect on the brightness of the light bulb if it's on and if no light bulb, pot adjustment won't light it either. I've been told that the top and middle leads of QD1 need switched (in other words QD1 top goes to ground and QD1 middle goes to R2/diode junction). Tried that and still no response.
This seems like it should be a simple circuit to troubleshoot, but I am out of practice for some time and not sure where to start. I've checked L1 out of circuit and it still has the proper resistance. I've also replaced the pot since adjusting it was getting me nothing, and still nothing with a new pot. The output from the doubler is correct at 300+ volts. Tried switching ignition primary wires, but still no effect. Instinct tells me that QD1 might be bad. Is there any way I can measure it out of circuit to be sure? What would resistances be between terminals?
Any suggestions would be greatly appreciated.
Thanks, John