To the best of my knowledge, the only way to control the speed of the motor
and retain its most of the torque at very slow rpm's is via a PWM scheme
based on actual shaft feedback.

I did this real simply once with an opamp and a smaller dc motor acting as a
generator.  I used another dc motor as a reference.  As I spun the reference
motor, the controlled one would duplicate.  Adding a comparator and an H
bridge allowed my to also control direction.  (this became the heart of a
model boat when I was a kid.... dead slow to full throttle).
----- Original Message -----
From: Justin Grimm <Justin.Grimm@SOUTHCORP.COM.AU>
To: <PICLIST@MITVMA.MIT.EDU>
Sent: Monday, August 26, 2002 2:03 AM
Subject: [EE]: DC motor control


> Does anyone know the best way to control the speed of a 12v DC motor
without
> losing too much torque? Would pwm work or just varying the voltage?
>
> Thanks
> Justin
>
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