At 11:30 AM 11/29/2004, Jinx wrote: >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. Why can't you just put the source lead from the N-ch FET in series with the sense resistor? Make sure that the flyback diode ties across the motor. In other words, what about the N-ch FET version doesn't work? dwayne -- Dwayne Reid Trinity Electronics Systems Ltd Edmonton, AB, CANADA (780) 489-3199 voice (780) 487-6397 fax Celebrating 20 years of Engineering Innovation (1984 - 2004) .-. .-. .-. .-. .-. .-. .-. .-. .-. .- `-' `-' `-' `-' `-' `-' `-' `-' `-' Do NOT send unsolicited commercial email to this email address. This message neither grants consent to receive unsolicited commercial email nor is intended to solicit commercial email. _______________________________________________ http://www.piclist.com PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist