Kai Klaas wrote:
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So, my advice is, to use a fast industrial motor driver integrated circuit,

I think your "worst case" is probably a bit too conservative Kai - a 4000 series gate (4049) can sink up to 40mA and source 12mA on a 12 v supply- say less than 10 ohms output impedance, bringing your charging times to nearer 50nSec than 50usec. Of course, you are right, a motor controller chip, or a "proper" mosfet driver IC would help anyway.

Frankly, I think John's problems are mainly the same as Stanley's - too much EMI and general crud flying around from an insufficient board layout.

Steve