On 27/07/06, John Chung wrote: > Richard, > > Are you saying that the current into the spark is > too low for the current clamp to detect it? > > John > I'm saying I'm not sure about it. For a given energy spark the energy = Volts * Amps * time so at a high voltage the current is going to be low. But against this, the actual voltage across the plug when fired is not that high, and there is probably enough capacitance in the circuit (coil windings - case) to produce a reasonable current pulse so you could be OK. The only inductive pickups I've seen have been on the primary side, and I've used capacitive pickups on the secondary. (But I'm not involved with motor testing other than to keep my own car running). If you try it you're likely to pickup a capacitively coupled pulse as well anyway unless you specifically screen the pickup coil against it. Richard P -- http://www.piclist.com PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist