Driving a Stepper
Mark Willis email (remove spam text)
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 <G> I can deal with verbal
humor, just don't physically harass cats or dogs (or people), in my
presence <G> 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!
I was thinking Sqrt(2) gain in torque, roughly, if you energize 2
> >> 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
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 <G>
> > 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 <G> 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 <G>
> >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 <G>
> 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 <G> Going to have to
balance torque out, or just assume that things get weird when you move
> 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 <G> We'll all cope. I've seen
them for $3ish, recently.
> Paul B.
See also: www.piclist.com/techref/io/steppers.htm?key=stepper
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