Jinx wrote:
> Yes, when the motor is turned by hand faster than say 4 or 5 steps per
> second, and the voltage goes up and the waveform is more defined.

A sensor that works on changing magnetic field is not going to work below
some frequency.  If you need steady state, then get a real shaft encoder.

Go back to first principals and see that what you really want is a
integrator.  In theory, the integral of open circuit voltage over one step
will be the same regardless of speed.  Below some speed however, the signal
is buried in noise and the offset of the integrator becomes significant.  I
would therefore set up a integrator with a opamp and bleed off the
accumulation capacitor at the lowest rolloff frequency you can tolerate.
For rates of about twice that frequency and above, you should get a roughly
constant size pulse.  Then you can use a comparator with a fixed threshold.

Note that this is a fancy way of deriving a single pole low pass filter,
just a different way of looking at it.


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