On Wed, 03 Feb 2010 03:50:26 -0800, Adam Aglionby wrote:
Cheap electric screwdrivers, high power motor and nice low RPM high
torque planetary gearbox, seen them used for aerial rotators before.

Agreed. Or cordless drill motors; I ripped mine apart a few years ago (I
hate cordless power tools) and built a little H-bridge driver and PWM
circuit for the motor so I could electronically control the speed.

(The body and battery from the drill ended up with an old car headlight
grafted to them which made for a nice little lamp to be used in
underground photography, so no bits were wasted :-)

cheers

Jules