On Fri, 17 Jan 2003, Richard Prosser wrote:

*>Er-
*>100Hz = 100 sparks/sec  = 50 revs/sec = 3000rpm for a 4 cylinder, 4 stroke,
*>single spark.

Er, right. My bad, I was thinking 4 cylinder 2-stroke.

Peter

*> I wote:
*>Pl = Wl * frequency [Hz]
*>
*>Pzener should be ~= Pl.
*>
*>With your numbers (100Hz assumes 1500rpm four cylinder four stroke
*>single spark per cylinder):
*>
*>8*10^-3*16/2 * 100 = 6.4W
*>
*>out of this a certain part will be dissipated by the coil and circuit
*>resistance so 5W is about right.
*>
*>The zeners will only be hot when the spark does NOT jump in the spark
*>plug. You could substitute a 300V spark gap for the zeners (rated 5-6 W
*>also). A secondary protector gap would be better imho (20kV rated).
*>
*>If you use series zeners then each can have a lower rating. F.ex. 6 x 1W,
*>50V zeners in series give 6W total, 300V.
*>
*>Peter

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