At 03:05 PM 9/12/2010, Brooke Clarke wrote: >If you're forced to use the spark you might use a HV cap to couple RF >into a spectrum analyzer and see where there's a strong signal (you >might force it using a tank circuit) and use the RF to confirm the spark. Yeah - I plan to look for multiple RF frequencies from the current=20 sensor on the ground electrode. I need to monitor the ground electrode so that an arc somewhere other=20 than to the ground electrode is ignored (fail-safe). I'm planning to=20 monitor for multiple frequencies for a couple of reasons: 1) a false-positive on one frequency does not by itself decide that a=20 good spark exists. 2) I fully expect that at some point, switch-mode continuous spark=20 ignition systems will appear. I don't want to be sampling that=20 frequency and thus get fooled by a short across the spark gap. Sampling multiple, non-harmonically-related frequencies solves both=20 of those problems. Again - thanks for the ideas! dwayne --=20 Dwayne Reid Trinity Electronics Systems Ltd Edmonton, AB, CANADA (780) 489-3199 voice (780) 487-6397 fax www.trinity-electronics.com Custom Electronics Design and Manufacturing --=20 http://www.piclist.com PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist .