Ramped SSTC - Power Supply Question + General Improvements

[ZakW]

Sounds like good performance.  Two possibilities come to mind for the bit of reduction you experience once packaged.  One is that the spread out circuitry may have acted like a counterpoise.  Perhaps try setting your coil on a large piece of grounded foil or other metal.  Other thought is that circuitry or frame structure may be close enough to primary and secondary to block some magnetic field or absorb energy from the field (induction heating).

I did include a auxiliary ground connection on the case for using a counterpoise but didn't notice any improvement. It was a 20x20in sheet of plywood covered in foil. When I was testing the coil and getting longer arcs my primary leads were longer, once I packaged everything up the primary was shortened a lot. That presumably changed the frequency and shifted it more or less away from what it used to be. Does that sound plausible? I could try a new primary coil with a few inches of extra wire to add some inductance back I suppose.

[davekni]

When I was testing the coil and getting longer arcs my primary leads were longer, once I packaged everything up the primary was shortened a lot. That presumably changed the frequency and shifted it more or less away from what it used to be. Does that sound plausible? I could try a new primary coil with a few inches of extra wire to add some inductance back I suppose.

For a DRSSTC that would be a likely issue.  For an SSTC, if any change, I'd expect shorter primary leads to increase current and arc length, and increase thermal stress on IGBTs.  However, I may not be thinking of all possible behavior changes due to lead length.  So perhaps try adding back in some length as an experiment (if you are interested in continued experimenting).  Or just enjoy your nicely packaged tiny coil and stop contemplating the details.

[ZakW]

Ha I think the latter. I got my hands full with the DRSSTC now .