> What is it that your sensor circuit measures? current?
> If you put the N-MOSFET on the low side and measure the voltage
> drop across D->S, you would get a pretty good idea of the current
> to the motor. (the MOSFET wouldn't heat up much to change the
> R_DS)

Presently there's voltage across a sense resistor which goes to a
comparator. In series with the motor are a pair of cross-wired
end-stop microswitches and the motor itself goes through a polarity
reversing relay. The person I'm doing this for originally had (what
he thought was) a good deal on 24V gearboxed motors. I added
an MC34063 booster and everything was sweet. Now he's found
a very cheap source of similar 12V motors but they're way too fast,
hence the PWM to slow them down. Unfortunately installations are
not all the same so he needs to set the optimum PWM in situ.else I
might have suggested a series resistor. There is a simple solution with
a FET in here somewhere, I think I just lucked out trying bipolars
and got side-tracked. As you do


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