In a message dated 98-01-15 18:58:16 EST, you write:

<< >
         If you have access to the front of the crank shaft, try mounting
 a disk with a notch cut out on to it and use a hall effect sensor. You
 will get a 5V pulse which is easy to count with the PIC's. It works for
 auto engine control so it should work here.

         If you have any questions email me.

         Peter G.
         peter.graham@dsto.defence.gov.au >>

Hello Peter,
A hall effect sensor won't detect a disk with a notch cut out of it.  An
optical interupter sensor will.  Hall effect sensors detect magnetic fields.
You could simply strap a good rare earth magnet to the crank shaft and detect
that with a Hall sensor.  They do that for auto trip computers.  I designed
one about five years ago.  We had a magnet held to the drive shaft by two
cable ties.  Worked OK.

Sorry to be nit picky
Dave Duley