Paul B. Webster VK2BZC wrote: > > You didn't reply to the *other* guy's comment on feeding the cats! Did, just in private; I was even polite I can deal with verbal humor, just don't physically harass cats or dogs (or people), in my presence You should hear the humor that people on Search & Rescue teams descend to, after 7 days of searching for someone who "Hadta get there now", was begged not to fly into a bad storm, and flew anyways - and never made it. I've heard FAR worse, guys! > Mark Willis wrote: > > > Makes sense - you can choose to always drive pairs of coils, though, > > for higher torque. > > I can't see that. The coil which remains energized in this switchover > contributes *nothing* to the torque except that by holding the armature > *in between* positions, it reduces the flux coupling. This may give an > extra repulsive kick at the start, but as it seems to me, less > attraction at the end of the stroke where it is pulling *away* from the > most-recently-energized pole. I was thinking Sqrt(2) gain in torque, roughly, if you energize 2 adjacent windings? > >> I'm sure you have *plenty* of spare plugs on the end of RD-BK-BK-YL > >> leads! > > "Never enough", despite the dozen spare power supplies in the garage > > It appears you, like me, can't bear to scrap equipment even when > busted! I use old connectors to make my own power Y-connectors, and STILL get stuck for buying more Y-connectors from computergate.com etc., dangit! Lots of machines here with lots of drives onboard > > Given the 5 wires (instead of 6), I remembered all that, summat > > vaguely but well enough as I've been watching the discussions in here. > > 5 and 6-wire units are almost identical, except that a 6-wire can be > used as either a 5-wire or a 4iwire :-). No comprendo how you get 4 wires out of a 6 wire unit? Unless you drive it with bipolar drivers & use the diodes to bypass half the coil, is that the trick here? > >> A diode should be connected across each coil winding. The Anodes > >> all connect to the Common wire, and the Cathodes connect to A B C > >> and D. > > AKA inductive kicks, yep. OK, makes sense. > > If we're getting particular here, the diodes do *not* go to the > common, but to common via a Zener or resistor. Whimper Seems people are always arguing this one, if via a resistor or Zener, how do you do the 6-wires to 4-wires trick? Why does "Jones on Stepping Motors" etc. have diodes across the coils? Or to Vcc and Ground, depending on coil type. Maybe it's a per winding type thing, this all is a lot of good info to re-load on > >I need a known speed motor control to spin a little cylinder or disk > > at a very high, controlled speed, for playing with a Nipkow heads-up > > display design for wearable computers. Need something like a 30+ Hz > > refresh rate for that, want some other motor then > > The complete assembly is available disposals from laser printer > mechanisms. Including electronics, though that may be a challenge. > > The capstan assembly from a Hard Disk Drive is an alternative. Lasers, I wish I had a spare, could seriously use 48 or 64 LED's at 1/300th inch spacing (That, with a 10-aperture Nipkow disk, would give me a nice HUD I could afford easily...) Aah, old HDD motor, now that's a good thought. Take an old 2.5" 40-megger or something & make it far more useful Going to have to balance torque out, or just assume that things get weird when you move while computing... > And yes, if you have to go *buy* a stepper driver, the L293D is the > way to go as it is created for the job. I'm miffed, they were available > once disposals but snapped up before I could get my order in. Happens, darnit. With me, I usually see a sale, then after they're gone, find I should've bought 'em all We'll all cope. I've seen them for $3ish, recently. > Cheers, > Paul B. Mark