"william_b_noble" wrote in message
...

ok, you asked. these are triac based controls that duty cycle modulate
the input AC power - basically they delay the turn on of the AC to the
motor until a desired phase angle is reached - the later the turn on
(each half cycle) the less power is delivered to the motor.

That sounds like PWM. Is that what these controllers are?

It is my understanding that a PWM drive will offer max torque over the speed
control range because the motor always sees peak voltage (but that the
voltage is chopped so that the average current determines the speed).

I am trying to build a power table feed for a mini mill. I've got a
high-torque 24VDC gear motor, but I'm still looking for an electronic
circuit to drive it. I know some people have used a light dimmer with the
output routed through a step-down transformer; perhaps a more version would
use one of these universal motor speed controllers in place of the light
dimmer.

Anyone have suggestions for either an economical off-the-shelf solution, or
a schematic for a basic PWM circuit?

Thanks!