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Re: SSTC- feedback vs. none

Original poster: "K. C. Herrick" <kchdlh@xxxxxxx>

Once more for the record, for anyone who's paid any attention to my drawing hot-streamer.com/temp/Half-br_res-load.jpg:

I've found in the hardware that there's not enough drive to Q5 & Q2 to turn them reliably on during spark events. So I'm having to re-do the driver portions to put the Q5/D16 and Q2/D15 elements ahead of Q1/Q3 and Q8/Q7--as I should have done in the first place. That way, Q5 and Q2 need only carry the base currents of Q1 and Q8 rather than their emitter currents. (Doing this, I find, in simulation, that I don't need resistors R16, R17 or R18. And adjusting the values of what were R3 & R11 by a few ohms tweaks the loop delay nicely for zero IGBT common-mode current...as before.)