On Mon, 20 Jun 2005 23:16:49 -0500, Don Foreman
wrote:

On Tue, 21 Jun 2005 02:20:40 GMT, "Tom Gardner"
wrote:

Yes, DC is an option but it seems more moola.

Maybe short term. It sounds like your motors are constantly stopping
and starting. Most AC motors are not designed for this, but DC
servomotors do it routinely.

And, if I finally understand your original approach, with your drive
unspooling just enough wire to reduce the load on your linear feeder,
the dancer arm with a pot and the appropriate control would regulate
the speed of the dc motor to avoid stopping or starting at all. The
speed would gradually increase as the diameter of the feed reel
decreased.

It doesn't even need to be an expensive servo motor. A cheap Dayton
gearmotor with the lowest price drive which would take an analog
signal for speed regulation would work. Or you could look for a drive
with a PI controller built in.

Good luck.

Pete Keillor