Hi Finn,My question is more about "why" the low value. In other words, what occurs different between 4700 ohms and 680 ohms for Roff? I of course realize the time base, but I'm more curious as to how the coil, power, sparks, or whatever is affected? For example, say with a given C1 and IGBT where we then know gate capacitance for the components used, how does changing an ensured off time (without charging compromises) differ from say taking it to the edge with a low value Roff? If the coil quenches in 2 primary notches and the components are set for 5, so what? Nanosecond delays are incurred until charging begins. But say I set the components for 1 primary notch turn off, well, then I'm attempting to force off current (which doesn't like to be forced off [and in my experience won't be forced off]).
I'm not saying the 680 ohm is not adequate, I'm simply saying I don't see the benefit electrically, so I'm asking about anything "else" that may help me realize why the low value? From my thought process, 5K or 680 ohms should perform similarly in this specific portion of the circuit (for a narrow band Fr of coils). But what of other frequencies?
Your CM-600 brick is a different flavor than discreet components. I don't really know how else to ask the question. If a coiler changes say a resistor value on the SISG (Ron or Roff), then why? What did or did not happen with original value? So often what is talked about is that now "I'm using this value". Never is there "why" I'm now using this value.
Bart Finn Hammer wrote:
bartb skrev:Hi Mark,The 680 ohm seems "on the edge" and specific to your coil. Were you trying to perform solid state forced quenching? This would be ok for some coils to a degree, but could be very risky to say my 70kHz coil that I'm running my SISG on where 330us is 3rd notch primary quenching. The 4700 ohm provides plenty of ring time without an IGBT energy crash and doesn't compromise charging. I'm just curious what you actually gain from setting Roff so low?Best regards, BartI am running 680ohms on my CM600 T-BrisgThe quench time is dependant on gate capacitance, C1 value but also on current trough IGBT. The gate-emitter capacitance is pumping charge into the gate by each oscillation.Cheers, Finn Hammer _______________________________________________ Tesla mailing list Tesla@xxxxxxxxxxxxxx http://www.pupman.com/mailman/listinfo/tesla
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