I've attempted a narrated demo of the Arduino telescope control project I've been messing with this summer. All bolted on the back of the homemade telescope mount.
Consists of Arduino Mega 1280 controlling two DC motors + encoders + gearboxes + worm gears via an L298 HBridge and PWM.
As well as tracking slowly to follow the stars, it can slew to different targets in the sky. The system is fully integrated via its own astronomy standard ASCOM driver so any PC astronomy planetarium software can use it.
The motors are precious metal brushed coreless Maxon motors with 512cpr (2048 in quad) encoders: These motors are superb, and capable of rotating extremely slowly: Handy for tracking the stars!http://youtu.be/d-jEStDotsU