You haven't mentioned anything about the variac inductance ... is this critical, or simply something that you can adjust the cap around. John, when you implement the circuit, what sort of inductance range are you typically using? Chris
Chris, I never measured the inductance, but I've used usually a 7.5amp variac. I don't think it should be too critical. But since you did get the 3 5o 5 volt resonant rise thats' a good sign. I'm surprised things didn't work better, I have no idea what's happening. THe mechanical phase shift will be only about 35 degrees or so, half of the electrical phase shift.John