I vote for the surplus servo motors.  The backlash on the power window
motors will probably drive you nuts.  I got two servo motors from
http://www.meci.com/ to build a tug to move my 3200 pound Piper Aztec around
(didn't need the encoder outputs). I bet those babies would have enough
power for your app.  Don't know if Meci still has those.

Nelson
nelson@nosuffering.com
www.nosuffering.com

-----Original Message-----
From: pic microcontroller discussion list
[mailto:PICLIST@MITVMA.MIT.EDU]On Behalf Of Spehro Pefhany
Sent: Monday, August 26, 2002 7:00 AM
To: PICLIST@MITVMA.MIT.EDU
Subject: Re: [EE]: DC motor control


At 02:36 PM 8/26/02 +0100, you wrote:
>Its for a plotter Im making.

Ah, the plot inspissates.

>I'm going to use an encoder for feedback
>(position) and maybe a PI loop. Its pretty heavy duty, Id use steppers but
I
>cant find any powerful enough. I want to slow the dc motor down as it
>approaches the encoder position I want. I was thinking of using power
window
>winder motors.

You might want to look for surplus servomotors. They generally have the
encoder
and are made for continuous duty service. I've seen them for very reasonable
prices, like $10 (US).

Best regards,

Spehro Pefhany --"it's the network..."            "The Journey is the
reward"
speff@interlog.com             Info for manufacturers: http://www.trexon.com
Embedded software/hardware/analog  Info for designers:  http://www.speff.com
9/11 United we Stand

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