10 minutes ago it sprung into life!
I have been struggling this week trying to get the feedback to work but the SSTC was dead.
The waveform from the GDT was good and the circuit board had been checked and rechecked.
If something doesn't work I try to sidestep and go around the other way
So I injected a sq wave at approx. 250 KHz into the feedback connection and wound up the variac
Nothing.
Then I slowly adjusted the sq wave freq and suddenly hit the sweet spot of the secondary's resonance freq.
A big flash over from the primary to the sec. Put some temporary paper between them and tried again...……
6 inch sparks now from the break out point and only slight warming of the mosfet's heatsinks after 5 mins.
If I cannot get feedback to work I shall drive the SSTC's with a 555 set at the sweet spot freq and switch it on/off with MIDI signals.
HT is a bit low so if I get that sorted the spark length should increase.
Will now start making second SSTC but first thing now
is a relaxing cup of coffee.
