3. I got the idea from an article in Scientific American on how to build this star tracker back when Comet Hale Bopp visited us.  Their plan didn't include a motor, instead you were instructed to turn the adjusting screw 1/4 turn every 15 seconds.  I decided to make two improvements to their plan.  1. Add legs to make it a complete self contained, full size tripod, and 2. Add a motor to turn the screw.