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Re: Recent s.s.t.c work



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

Update: I've added a few 5 V bypass capacitors & replaced a probe's ground-clip & now I find that I actually have negligible phase shift thru my 1:1 transformer and "pilot oscillator" circuit. But I do see a significant shift thru the capacitor in series with the primary of the H-bridge's drive transformer. It's currently only 3 uF so I will have to increase that quite a bit.

But I'm running out of room on the board. I was amused by the proliferation of probes pursuant to this testing (an HP, a no-name and an ancient Tek) so I took a photo of it:
http://www.hot-streamer.com/temp/KCH_TCH6.jpg
The capacitor in question is the tubular one directly to the right of the probe with the red sleeve.


Those who recall a prior photo will note the surgery I've had to do on the board: adding a daughter board at the lower right to accomodate huskier transformer-drive transistors, adding another daughter board across the center to accomodate huskier plus-going gating transistors in the 4 IGBT-gate circuits, and sawing off a whole section of the board directly above the gate-transistor board so as to completely replace the rest of the 4 drive circuits. I am too old for this.

If anyone's further interested, the blue/white tw-pair conducts the feedback from the 1:100 primary c.t. inside the bucket while the small gray tw-pair leads from the 4 m-ohm current shunt in the mains-capacitor bus to the scope. The two diagonal white objects are just part of a lifting bridle.

KCH