Paul wrote:

Peter Nunn wrote:

Thanks for that paul, finally got it.  I now know what is going on in the
sensor unit. Many thanks for your responses to this drawn out conversation

Peter, a mag pickup on the flywheel ring gear teeth is ideal for determining the RPM.
All you need is one more mag pickup and a bolt back there to get the top dead center.

Paul Lamar

BTW Peter, the rate of pulses from the flywheel ring gear teeth is such
that RPM can be directly read (no math) from an internal pulse counter if 
the CMOS PIC CPU is periodically interrupted on a regular basis. Say every millisec.
I used that trick for twenty years in my Road Test equipment.

Paul Lamar
 
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