[ischmitz]

OK, I am playing with Circuit Maker and its more evolved cousin Altium Designer 6 and I simply can not get the circuit to work right in its shown configuration. The Darlington pair Q2/Q3 does seem to turn on with each pulse (300V pulses from the CDI box) However, I can not seem to get a nice signal that would get integrated properly in the Amperemeter. The most useful value for the C3 seems to be 0.47uF. Apparently it controls how long the monostable vibrator stays on when triggered.

Have you measured the resistor network R5 R11 R12? It should be something in the lower 1K range, right. I assume the wire-wound resistor is the calibration element and the thermistor corrects for temperature variations.

Also I don't understand the Zener diode and what it accomplishes since it is forward-biased. When I turn it around it at least start to operate.

Cheers,
Ingo