The key here is the type of motor you are trying to control.
If it is a "universal" type (ac/dc with brushes), you can
easily control it with a solid state "dimmer type" control
(although some work better than others). If the motor is
an induction motor (like many grinders etc - no brushes,
uses the rotating AC magnetic field to spin it), the only
real way to control it is with a variable frequency drive
since the speed of the motor is determined by the frequency
of the AC applied to the windings.

mikey

"Robert Swinney" wrote in message
...
An incandescent lamp dimmer is a different animal than a universal AC/DC
brush-type motor speed control such as the one sold by HF. They are not
interchangeable.

Bob Swinney
"mclorson" wrote in message
oups.com...
Interesting, I tried to make a similar device using a lamp/light
dimmer and a switch to use on my grinder. The grinder would start slow,
but soon speed up to almost full speed. I couldn't get the dimmer to
control the speed. I assumed I was using the wrong dimmer switch
arrangement. Any homebrew ways of doing this?
-Mike