DC Motor Control

[cstoos]

I am in the early stages of the design of a telescope mount and I need a control motor. I am hoping to run it on a battery so I think a DC motor is the way to go, but I need to be able to keep the rotation speed extremely constant for photographic purposes.

So, to my question: Does anyone know of a controllor that can maintain a constant speed with a varying (or most likely, decaying) power input into the motor? If you do, is it small enough to be incorporated into a portable telescope mount?

Edit: I am trying to keep it low cost, which is why I am looking at Servo alternates for now.

[marcusl]

The conventional approach is to use an AC clock motor driven from a battery-operated inverter. The inverter frequency can be fine-tuned to track the stars.

[cstoos]

What kind of torque can I expect to see out of something like that? This design is going to be a bit beefier than most common mounting systems.

[marcusl]

You'll have to look into it. Keep in mind that you will gear down a 1 rpm clock motor by 1:1440 to turn once per day, so you'll get torque multiplication.

[dlgoff]

I'm totally ignorant when it comes to telescope tracking drives.

Once you get that project completed, you might be interested in russ_watters thread on Peltier Temperature Controller (http://www.physicsforums.com/showthread.php?t=394267) for his telescope for picture taking.

[kubing]

good project bro. keep it up