I`m refurbishing my HT-room, and want to do a CIH-setup. I`m moving the amps, sources and projector to the room behind the back wall. I will be using an A-lens, and have been thinking of making a lift for the lens that can be built into the back wall. At first I thought of making a slide, using the inside of a flat bed scanner. I tried this, and I think it would have worked, except that the lens would block the ventilation openings of the projector. So to avoid this I made a lift instead of a slide. The scanner stepper motor didn`t have much power, and was not suitable for a lift. Might have worked with a reduction gear, and balancing out the weigth of the lens.
So I used a DC-gear motor instead. The motor is powered from a H-bridge. The H-bridge is controlled from a micro-controller, which get input from IR and an upper and lower position switch. If a switch is reached, the micro controller stops the motion, and stores the status in eeprom. So the status is known, even after a power cycle.
I uploaded a short video here
to show it in action