I'm also thinking about an el cheapo rotator based on a pan/tilt base. (In fact search el cheapo rotator for an article about doing the same thing manually). The pan/tilt that I was going to start with does have a "center" command as well as 4 memories where you can remember previous positions. It is based on steppers, not A/C, though.

Anyway, I was thinking about programming 4 strategic positions into the memories and using them with "center" to get close to where I want to be, and then send step commands to get more exact. Requires some programming of course, but that's what Arduinos are for!

I *like* the MEMS compass idea. Pretty cool!

Burns Fisher, W2BFJ