Alt-BEAM Archive
Message #11081
To: beam@sgiblab.sgi.com
From: "Timothy Flytch" flytch@hotmail.com
Date: Tue, 29 Feb 2000 00:14:54 PST
Subject: [alt-beam] Re: Re:Diskette Drives
Ok here is the history... My friend and I found these motors at the local
scrap yard ... still new in box... $0.05/Lbs... only problem they have three
wires... the boxes said "step" so we called them stepper motors (now I
dought it)... we bought a couple ... spent less then a quarter for both...
and tried to see if we could use them for something... our final conclusion
was that we could buy better regular motors for what we could build the
drivers... we just tossed them out and went on... this was in 1978 or so..
but the letter about disc drive motors reminded me of them...
Question...
1) Were these stepper motors ???
2) Cold using this type of motor provide enough feedback for a waker???
Timothy...
>Timothy,
>
>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?
>
>BTW There are no STUPID QUESTIONS...
>
>
>Timothy Flytch wrote:
>
> > why not use a stepper motor... If you set one up WITHOUT a driver or
>gear
> > box... that is as you apply power to a stepper across one coil it will
>turn
> > about 120' ... 1/3 of a turn??? now if you set up the walker with legs
> > mounted directly on the shaft ... wouldn't you get feedback enough for
>the
> > neuron loop??? and yes I do see similarities to using solenoids for the
>same
> > function... but still you are generating a increase in field through a
> > coil... isn't it the same as loading a moving motor???
> > Timothy...
> >
>
>
______________________________________________________
11082 Tue, 29 Feb 2000 00:40:11 PST [alt-beam] Re: mini walker beam@sgiblab.sgi.com "Timothy Flytch" >Is there a way to focus the magnetic field to a smaller area, yet not be
>attracted to a magnet when no power is applied. I assume that's what
>iron cores are for, but the tiny magnets I'm using are very powerful,
>and they stick to the iron cores. is there a special type of core I
>should use, or can I use one of those ferrite cores? Can ferrite cores be
>cut? I know they chip. The magnets are 1/4 inch diameter,
>
I can't answer all your questions but these two I can... Try a coper core...
it works well but is too expensive for production (or so I've been told)
And yes you can cut ferrite ... just have to use the right blade... when I
worked at eb's we cut , bevelled, ground, and sand blasted(glass bead)
them...
Timothy...
>Absolute worst case, I'll mount coils in front and back of the robot
>instead of on the inner side of it. Might not look as nice, or be as
>compact, but if it makes it work.
>
>I've completed a frame for my robot, and it's unbelievably nice. all
>joints are very low friction. I used brass screws and guitar wire. It
>all solders together nicely. As joints, I put the screws half way in,
>and then make the joints. I highly recomend it if you need a small joint
>that's easy to work with.
>
>I've essentialy put together a tiny 1.5 inch long walker that is driven
>by coils like on a magbot. I'm still deciding what type of driver to
>use, but I want it to be a single chip device. Solar power, or at least
>solar assist is desirable. Because it has no motors or electricaly
>active joints, there is practicly nothing to wear out! I was going to
>fully complete the bot before announcing it, but I'd like to hear
>people's advice on making it as efficient as possible. I want this bot
>to be definitely worth while.
>
>I'm sending a picture to show how small it is. All I need are 2 "major
>henry" strenth coils. I'm going to see what kind of speaker wire is
>avaliable localy and wind my own coil. I'll have to dig up my text books
>from last year. Figure out the best possible coil configuration.
>
>Oh, here's a question aimed for Ian. Does your almost complete walker
>circuit work with inductive coils? I'm assuming it does, since motors
>use inductive coils. Unless I'm told otherwise, I'm working on the
>assumption that it will drive inductive coils, and will be able to
>reverse the polarity when the switch is hit.
>
>I'd call the thing Walkman Jr., but I already took the name! I may drop
>the Jr. off my original, my first bot, inspired by Tilden's Walkman,
>since I always forget it anyway. Then the REAL junior can have the Jr.
>label! :)
>
>What's everyone think of this?
>
>
>Dave Hrynkiw wrote:
> >
> > At 07:53 PM 2/28/00 , Richard Piotter wrote:
> > >Would one of those major henry coils put more kick wound as it is, or
>if
> > >it were wound into a more compact form?
> >
> > I designed the CMH (major henry coil) to the specs provided by Mark
>Tilden.
> > From what I got from him, a large diameter coil with as small a center
> > ole as possible was the best way to get a large projected EM field. He
>said
> > ideally, a single-wire thickness coil as large a diameter as possible
>would
> > be ideal.
> >
> > >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:
> >
> > Why not? I can't provide you with the calculations (I have
> > them...someplace...), but I imagine you need as many turns as possible
>with
> > as low resistance you can get away with. There's a balancing act there
> > (thinner wire=more turns, but more resistance).
> >
> > >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?
> >
> > Miller has had success using plastic sewing bobbins as cores for coils,
>and
> > "magnet" wire is pretty inexpensive. Look at surplus sources. Chuck that
> > coil into a dremel, and zoooooom! One coil!
> >
> > Good luck,
> > 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
>
>-- Make Money by Simply Surfing the Net or responding to E-Mail!!!
>-- Click below!!!
>
>http://www.alladvantage.com/go.asp?refid=ATL147
>http://www.spedia.net/cgi-bin/dir/tz.cgi?run=show_svc&fl=8&vid=329630
><< MicroWalker.jpg >>
______________________________________________________
11083 Tue, 29 Feb 2000 01:18:47 -0800 [alt-beam] Re: Diskette Drives/camera parts Zane Bryan Saw someone talking about geared motors from lens assemblies for around 30 dollars...I have six from
free cameras...a MUCH better bargain, don't you think?
content-transfer-encoding: quoted-printable
>
=
compared to the hundreds of dollars that I would rather be spending on some=
=
really high quality motors.
Dane =
Gardner
BTW...kewl name.
From: Zane =
Bryan
Saw someone talking about geared motors from lens assemblies f=
or =
around 30 dollars...I have six from free cameras...a MUCH better bargain, d=
on't =
you think?
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