On 26.08.14 05:13, Gene Heskett wrote: > I have a box in the basement with 4 ea small steppers designed to run from > a 24 volt supply, and a bunch of comparators to convert the induced > voltages into an A/B signal, was going to use them as jog wheels, but the > one time I tried to setup a test to see if the idea had merit, I found > that by the time I had added enough hysteresis to the comparators, the > minimum speed at which a reliable signal could be obtained was faster than > I had envisioned for fine control. Doable, yes, practical for the job, > no.
Adding a bit of DC excitation appears to be the secret. About a fortnight ago I stumbled across a hardcopy I'd made from out there on the web somewhere, showing a 680 ohm resistor from each coil end to +5v or ground, and a LM339 comparator picking off the coil emf, IIRC. Unexcited, the generated emf was dismal (as you've confirmed), but leapt to hundreds of millivolts (i.e. heaps) with the coils lightly energised. Cogging (detent action) increases a bit, giving improved jog wheel action, according to the author. Due to a lacking round tuit, I haven't yet gone as far as you Gene, to make one up for storing in a drawer for later. (Came back a couple of hours ago, from a fortnight on the farm. The fences are whole again, with no more trees through 'em, and I have another load of firewood to get me through what's left of winter. Three local council workers turned up on one say, to clean up the heavily wooded lane which runs along one boundary, and dropped another tree through the fence. Still, I can't complain that we pay our rates, and I never see them way out there.) Erik -- What's right is what's left if you do everything else wrong. - Robin Williams ------------------------------------------------------------------------------ Slashdot TV. Video for Nerds. Stuff that matters. http://tv.slashdot.org/ _______________________________________________ Emc-users mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/emc-users
