Inductive Pickup Circuit

[John S Gwynne]

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   In message <199510152309.TAA11230 at coulomb.eng.ohio-state.edu> , you write:
 
| pickup works.  The ignition system is nothing more than 
| an HEI distributor driven by a motor, and 4 spark plugs.
| My goal is to make a negative transition logic pulse
| from the pickup to drive a counter circuit.

Why not use the tack port on the HEI? i.e., count the driving waveform
pulses on the coil primary (divide by 4) rather than the output on the
secondary (magnetically coupled at the spark plug wires). Both have
considerable ring, but it's *much* less on the primary side and easily
filtered. The primary on the HEI is basically 0-12V. I recall using a
high speed comparator and a little filtering for a vary reliable TTL
tach output... just a thought.


                                       John S Gwynne
                                          Gwynne.1 at osu.edu
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