"Don Foreman" wrote in message
A friend and I were just discussing ways to know the orientation of a
telescope's equatorial mount. One guy wants to get 12" to 15" brass
gears made and use rotary encoders. That'd work, but I was thinking
that it could also be done electro-optically with a pattern on a disc
or strip.

Don, generate your Acad dwg, or I could do same. Be more than happy to plot
it for you.

Ivan