I built this ZVS driver to make some big high voltage sparks a while ago. It worked off three voltages 24V, 50V, and 80V and had no issues. The only part of it that got really hot were the 1kohm 3W resistors.
Recently I decided to play around with coil guns so i used it to charge up a capacitor bank as show in the picture. The rectifier diodes are just regular 4007's
The problem I'm having is this. When i charge up the capacitors it doesnt make a high pitched whine like it normally does, it (the transformer, which is a ferrite core from an old TV) makes this really awful chattering sound that starts off really rough sounding and eventually turns into the whine as the capacitor fully charges. Seems like a current issue where its drawing more current at the initial stages of charging and less as the voltage in the cap rises. However, it doesnt do this when i simply shortage secondary and that should draw maximum current. After a few charges, for the first time ever, the MOSFET's were actually really hot and the chattering sound became random and the MOSFET's failed (due to over heating).
So my questions are:
Does any one know what went wrong? Why is the transformer chattering and how do i make it stop?
I think i should have used UF4007's for the rectifier and I'm wondering if 1Kohm at 24V input is too high and i should go with the typical 470ohm. Maybe the high resistance is allowing the MOSFET's to stay on too long which might cause poor oscillation and cause the chattering?