have the op amp clip the wave so all you get are peaks, and just have an
inverter convert the waveform to a ttl square wave. count the frequency
from there.


On Thu, 25 Jun 1998, Bruce Turrentine wrote:

> I am working on an automotive timing circuit that uses a toyota reluctor pick
> up. It's output is a pseudo sine wave that changes in frequency and amplitude
> as the rpm changes. The ideal point to in the wave to send a position
> interrupt is as the wave passes zero. I've tried running it through an op amp,
> letting the wave swing from a 5v pedestal, and computing the midpoint between
> the two peaks but this eats up too much time is an "after the event has come
> and gone" solution. Anybody have a suggestion?
>
> Bruce
>