Alt-BEAM Archive

Message #11063



To: beam@sgiblab.sgi.com
From: Ben Hitchcock beh01@uow.edu.au
Date: Tue, 29 Feb 2000 14:08:32 +1100 (EST)
Subject: [alt-beam] Re:Diskette Drives


Hi,

> Stepper motors draw a fair amount of amps, depending on the voltage and size of
> the motor. This makes it very difficult to power with an SE. Also most steppers
> only move around 7.5 degrees/pulse. So you need somekind of driver. So far the
> simplest driver I've found still needs a min. of 2 ICs, a driver and a 555
> timer.
> Plus the motors aren't much cheaper than the geared motors that are out there
> on the market for ready sale. By the time you add the driver and timer to
> generate the pulses it is more expensive. Complete driver boards, in kit form,
> run around $30.00 Canadian for a good one, no motor. And a driver can only run
> one motor at a time. If you have the coin to spend...
>
> Does anyone else know of a stepper motor driver that is simpler? Or cheaper?

I've used a microcore to drive a disk drive stepper motor directly. The
torque was abysmal, but it did spin reasonably well. Mine had six leads-
two sets of three. Just keep swapping 'em around until it spins around.
Also, pinch some tape onto the motor shaft to see what the shaft is doing.
Otherwise it just goes 'tick tick tick' and you can't see whether it's
spinning or just oscillating back and forth.

Chip: one 74HC14
Components: six 0.22 uF caps, and six 1Meg resistors. And a 3V supply.

If you really desperately want to get it going then try it otherwise don't
bother. Most DC motors far outperform this setup.

Ben



11064 Mon, 28 Feb 2000 17:57:04 -0600 [alt-beam] Re: building caps? alt-beam@egroups.com Ben A Micklin you mean the kind on Command and COnquer that destroy your tanks and
troops?
I guess your very dangerous then.....hehe.

~ben~

On Mon, 28 Feb 2000 17:16:08 -0500 walkau writes:
> Timothy Flytch wrote:
> >
> > >I'm confused. What does the voltage reading actually have to do
> with it??
> > >-William
> >
> > I have been meaning to through this out for a long time...
> > when I was in high school some of my friends and I built a Tesla
> coil...
> > well we also built the capacitors for it... were talking thousands
> of
> > volts... we learned that the aria of the plates determines the
> capacitance
> > and the distance between determines how much voltage it can
> handle... Too
> > high of voltage and you get arcing between the plates... we used
> aluminum
> > foil and glass plates... A little crude but it was what we could
> scrounge as
> > high schoolers...
> > how dose this apply to beam??? caps are made using metal foil and
> an
> > isolative layer of plastic film which is then rolled up kinda like
> a
> > sleeping bag... the higher the voltage the thicker the plastic
> film is...
> > this directly affects the size and weight of the guts of the cap
> get... It
> > then needs a bigger heavier container to hold it (can)...
> > hope this made sense :)
> >
> > Timothy...
> > ______________________________________________________
> >
>
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11065 Mon, 28 Feb 2000 22:41:57 -0800 [alt-beam] Re: mini walker "Dennison Bertram"

Well coils aren't hard to wind. Just wind up the wire like it was in a roll.
Try to keep the wire even however. That's important. Maybe try winding it
around a screw perhaps, or something like that. You'll honestly have to
experiment with it.

dennison


Would one of those major henry coils put more kick wound as it is, or if
it were wound into a more compact form?

The major henry coils are like the following:
_____
|| / \
|| / ,-. \
|| | | | |
|| \ `-' /
|| \_____/


The robot I'm woking on needs the kick those major henry coils put out,
but the space is limiting. It'd be much easier to have a could shaped
like the following:

______ ___
| | / \
| | | O |
|______| \___/

Is there anything special to winding coils? would the major henry coil
have as much kick as it curently does if it were rewound like the lower
picture?

I appreciate any advice. I need that kick, but space is limited. I'm
using Radio Shack Part # 64-1895 Rare Earth Magnets. I need the coil to
be able to pull and repel the magnet across about 1/4 inch horizontal
movement. The coil works, but it simply is too large (diameter wise) for
my project. 3/8 inch is the maximum diameter that will work without the
core being off center from the magnets.

Have any advice?

Thanks!



Dave Hrynkiw wrote:
>
> At 10:29 PM 2/27/00 , Richard Piotter wrote:
> >Your "major henry" coils... Can they be unwound and then rewound on a
> >new core without damaging the enamel coating?
>
> ...I think so. I regularly "pull" off wire from the coils to make longer
> leads. But the re-winding portion is a nasty bit'o'business. Not fun to
> spool it up and try to re-glue the windings. What you have in mind?
>
> >How fast do those things
> >usualy trigger in a Solar Engine like a Magbot?
>
> Same time delay as any other SE - depends on the voltage trigger, cap
size,
> and sunlight. But in regards to discharging, they're just as quick as a
> motor. After all, they're what - 13 ohms?
>
> >What size solar panel
> >would you recomend to drive a Bicore and and SE that is time triggered
> >off the Bicore?
>
> ...to drive a bicore and a SE? I'd probably want to stick with the 5V
> cells, being the 3733 & 3766, as the '240s all run better on higher
voltages.
>
> Regards,
> Dave
> ---------------------------------------------------------------
> "Um, no - that's H,R,Y,N,K,I,W. No, not K,I,U,U, K,I,_W_. Yes,
> that's right. Yes, I know it looks like "HOCKYRINK." Yup, only
> 2 vowels. Pronounciation? _SMITH_".
> http://www.solarbotics.com

--


Richard Piotter The Richfiles Robotics & TI web page:
richfile@rconnect.com http://richfiles.calc.org

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