Graham Gunderson's Energy conference presentation Most impressive and mysterious

[TinselKoala]

... only, on the photos of Gunderson's logic board and in Spokane1's schematics, there is no adjustable element (micro trimpot or trimmer cap) in the U3 556 clock circuit. It is wired to produce a fixed frequency.

[k4zep]

... only, on the photos of Gunderson's logic board and in Spokane1's schematics, there is no adjustable element (micro trimpot or trimmer cap) in the U3 556 clock circuit. It is wired to produce a fixed frequency.

I do remember in the video when he was trying to get the RH power monitor to settle down, he adjusted something on the board with a little screwdriver and it did seem to affect
the jittering that was going on. Sort of shruged his sholders and continued.  It seemed as time went on, drift or whatever, he didn't seem to worry about displayed measurements but more about discussing the device.

Ben K4ZEP

[TinselKoala]

Yes, but whatever he adjusted then, it wasn't the U3 TS556 timer "master clock". Unless he rewired the logic board between the demonstration and the time the photos were taken.

Note: In Spokane1's schematic he has the timing resistor as 680R, but on the actual board photo it appears to be 22k.On my breadboard the 680R gives a frequency of about 52 kHz or so, and the 22k gives a frequency of about 2.54 kHz.

[Spokane1]

... only, on the photos of Gunderson's logic board and in Spokane1's schematics, there is no adjustable element (micro trimpot or trimmer cap) in the U3 556 clock circuit. It is wired to produce a fixed frequency.

Dear TK,

Good catch. You are absolutely right. There is no adjustable trim pot on that timer. The adjustment on the master 74HC123 chip would be the only one that could impact the frequency of operation.

Perhaps there is an advantage in adjusting the frequency of operation for this process rather than that of the power supplies.

Thanks for keeping my ducks in a row.

Spokane1

[verpies]

I suspect that Graham didn't need the horsepower of that driver, but happened to have several on hand.
...
I suppose another IXDD614 along with the needed storage capacitors to supply that 16 Amp turn on pulse. I wouldn't doubt that all the components on that mini circuit board are of the surface mount variety.

I don't understand.  Are you suggesting that there are some IXDD614 MOSFET drivers that provide 16A turn-on/off pulses and some that provide only milliamp pulses?
IMO single milliamps are not enough to charge/discharge under a microsecond the 161nC gate charge, formed by the 2773pF gate-source capacitance + gate-drain Miller's capacitance multiplied by the MOSFET's transconductance ( 15pF * 23.6 = 354pF ).

Also I'm sure that +12 volts needs to be something higher since those SiC MOSFET's typically need +25 gate voltage plus what ever over drive pulse people want to use.

But this datasheet lists a mere 4V gate voltage needed to turn-on this MOSFET ( V_GS(th) ) while the maximum tolerable gate-to-source voltage ( V_GSmax ) is listed as +25V and -10V negative.  Exceeding these maximum ratings leads to gate insulator damage (MOSFET damage).