Re: re: Bipolar question ?MOSFETS

Hellow fellow solid state fans!

I've been using a capicitor/ resistor in series for snubbing, I've seen an
>arrangement. However I didnot consider the turn on current, I assumed that the
>the primary coil was inductive and therefore it would limit the turn on
>But of
>course it is a transformer, so below resonance its an inductor, above resonance
>a capacitor and at resonance its a resistor, that explains quite a lot, now I
>have to consider
>delibrately putting an inductor in series with the load (with a diode in series
>with a
>small resistor across it). 
>I reckon that at 75v and 4A, I'll need 5uH to slow the current rise over 250ns,
>resistor) does that sound right anyone? 

There should be some leakage inductance in your primary? I would think.

Question ? How do you measure leakage inductance?

to avoid "shoot thru". 

Drive FETS using a transformer three wires twisted together then wrapped
around a ferrite
donut. One for input, and one for each gate to source. Drive with a square wave.

Feedback is helpful, my coil (when
it works) goes off frequency as soon as you approach it and I have to keep
adjusting it. 

Feed back is the only way! That is the real advantage of solid state coils.

Paul Harriman US