These are pricey but offer 5900 steps over 120 degrees. 0.02 degree per step. At least you could try a couple. If you have many of them it would get expensive quickly.
http://www.horizonhobby.com/ds8231-ultra-precision-servo-jrps8231 Sent from mobile > On Jul 5, 2015, at 7:46 AM, Jim Lux <[email protected]> wrote: > >> On 7/4/15 7:53 PM, Hal Murray wrote: >> >> [email protected] said: >>> Exactly... I've got an array of mirrors on az/el mounts (two servos >>> stacked) and the reflection from the mirrors on the wall forms the display. >> >> How many pixels in that display? Or what is the unit of quality measurement? >> >> What sort of ADEV are you aiming for? If your goal is solar time rather than >> TAI or UTC, you should be able to get pretty good. > > > Prototype is 6 pixels to demonstrate concept and work out the bugs. Long > term, probably several dozen. > > Time Accuracy? better than a second > > Turns out, having done some experimenting, the real issue is angular > accuracy. RC servos aren't all that great, and have significant jitter > (probably not an issue in their design application which tends to have good > mechanical low pass filtering). They're cheap and easy to use (as in, I had > a bunch in the garage I could cannibalize out of another project). > > But if you have 3x3 inch mirrors (call it 7.5 cm), and want to create a > picture on the wall that's, say, 10 meters away, you really need angular > pointing of 0.007 radians.. that's about 1/2 degree. An RC servo has roughly > 270 degree rotation corresponding to 256 steps of PWM (in the Arduino > implementation). > _______________________________________________ > time-nuts mailing list -- [email protected] > To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > and follow the instructions there. _______________________________________________ time-nuts mailing list -- [email protected] To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
