Crank Trigger Signal (was monitoring RPM)

[Orin Eman]

> Whats wrong with putting a hall sensor really close to hte flywheel teeth,
> as there is prolly close to 100 or more teeth on that and the sharp edges
> may be enough to trigger the sensor, another pickup could be used to
> detect TDC, so you can have both rpm, and position, with a decent amount
> of resolution.   Renault had a similar system for their ignition, as it
> used a crank trigger sensor that read larger "teeth" (they look like
> square blocks right behind the flywheel teeth) and missing teeth at tdc.

You can find such sensors on any Audi 5000 turbo.  They aren't hall tho',
you need some signal conditioning.  They count flywheel teeth (135 per
rev in this case) and there is an extra pin 62 deg BTDC with a separate
sensor.  

Orin.