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Stepper Motors

GumbyGumby Posts: 24
edited 2006-03-08 13:42 in Robotics
I have several Steppers motors (Epson EM-289 EM-293) recovered from broken printers. I have scoured the web to find information on them and I how could use them in robotic applications. I found next to nothing. I do not have specs, such as uni. or bipolar, voltage, wire labels(4 of them 1 being black) etc. I came across some info on the use of a ULN2003 to control steppers but I am not even sure if this would work. Would anyone have any information on this subject/these motors? Thanks in advance for your replies.
Gilles
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Comments

  • Chris SavageChris Savage Parallax Engineering Posts: 14,406
    edited 2006-02-24 06:07
    Gumby,

    ·· You will need to do some research and find the information on these if you plan on using them.· It's that or get out the ohm meter and start testing wires to see what coils are what.

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    Chris Savage
    Parallax Tech Support
    csavage@parallax.com
  • LoopyBytelooseLoopyByteloose Posts: 12,537
    edited 2006-02-24 15:24
    Take a resitance measurement on the coils to determine a ballpark figure of how much power you might use.

    Assume that you are going to power them at 5 volts [noparse][[/noparse]because most steppers are 5 volts or more] and if they require over 500ma of current per darlington, you probably cannot use the UNL2803 [noparse][[/noparse]the UNL2003 has only 7 circuits, not 8]. The total power limit of the ULN2803, is about 2 watts at 25 degrees Centigrade and goes down at it gets hotter. Watts = Amps x Volts.

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    "When all think alike, no one is thinking very much.' - Walter Lippmann (1889-1974)

    ······································································ Warm regards,····· G. Herzog [noparse][[/noparse]·黃鶴 ]·in Taiwan
  • Chris SavageChris Savage Parallax Engineering Posts: 14,406
    edited 2006-02-24 15:33
    Kramer,

    ·· In my experience most of the Stepper Motors I have seen are 12V or 24V with 12V being the more common.· The ones we have carried all had current ratings well within the capabilities of the ULN2003/ULN2803 due to only needing one or two coils energized at any given time but usually only one.

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    Chris Savage
    Parallax Tech Support
    csavage@parallax.com
  • LoopyBytelooseLoopyByteloose Posts: 12,537
    edited 2006-02-25 15:24
    Thanks Chris.
    I tend to derate things when guessing. I suspect that the insulation of the enamel wire they use in motors is generally good to over 100 volts or more if not overcome by excessive heat.

    After all, do they really make 5volt, 12volt, and so on enamel wire? Too much inventory.

    Since there are no brushes to burn up, it is all a question of how the cooling was designed.
    I do seem to recall some Apple II printers had big 3.5 volt steppers [noparse][[/noparse]at 3.5 ohms per coil!].

    What Gumby may really need to indentify is what printers they came from as I doubt if people know as much about Epson motor numbers as they do about the printer as a whole. If he can find a schematic for the printer, the power to the stepper would likely be obvious. Maybe a repair person could recall based on the model.

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    "When all think alike, no one is thinking very much.' - Walter Lippmann (1889-1974)

    ······································································ Warm regards,····· G. Herzog [noparse][[/noparse]·黃鶴 ]·in Taiwan

    Post Edited (Kramer) : 2/25/2006 4:41:28 PM GMT
  • Paul BakerPaul Baker Posts: 6,351
    edited 2006-03-01 17:58
    For all intents and purposes its not the voltage on the wire that matters, its the current running through it, designed properly you could hook up hundreds of volts on the thinnest enameled wire if you limit the current running through it. But I don't suggest attempting it.

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  • GumbyGumby Posts: 24
    edited 2006-03-03 00:10
    Thanks for all the info. So far I figured out a few are bipolar, the windings have 9.3 Ohm resistance.
    Now I need a schematic/chip connection to use them with my Basic Stamp at the highest torque.
    Any suggestions where i can find such information.
    Gilles
  • LoopyBytelooseLoopyByteloose Posts: 12,537
    edited 2006-03-05 13:34
    Well, 9.3 ohm at 12 volts is over 1350ma. At 5volts it is still over 550ma.
    Too much for UNL2803. And the UNL2803 only does uni-polar.

    The L298 will handle 4amps and 35volts. And I think it works with either Uni-polar or Bi-polar.
    The only problem with the device is DIY wiring. It has a lot of I/O very close together.

    A kit or a board graphic will help you along. Google and you will find both [noparse][[/noparse]I did a while ago, but I haven't kept them]

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    "When all think alike, no one is thinking very much.' - Walter Lippmann (1889-1974)

    ······································································ Warm regards,····· G. Herzog [noparse][[/noparse]·黃鶴 ]·in Taiwan
  • Bruce BatesBruce Bates Posts: 3,045
    edited 2006-03-05 14:32
    Gumby -

    You may or may not be able to use a ULN2x03 Darlington Array to drive your stepper motors, but it depends on the current required and not the type of stepper motor being utilized (uni-polar or bi-polar). The example supplied· (attached) with the stepper motor that Parallax sells shows how the chip can be applied, and offers some sample programming.

    Regards,

    Bruce Bates


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    Stepper_Motor_27964.pdf
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  • ToneTone Posts: 3
    edited 2006-03-06 03:39
    Sample program is very interesting and versatile. Thanks !smurf.gif
    Bruce Bates said...
    Gumby -

    You may or may not be able to use a ULN2x03 Darlington Array to drive your stepper motors, but it depends on the current required and not the type of stepper motor being utilized (uni-polar or bi-polar). The example supplied· (attached) with the stepper motor that Parallax sells shows how the chip can be applied, and offers some sample programming.

    Regards,

    Bruce Bates


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  • LoopyBytelooseLoopyByteloose Posts: 12,537
    edited 2006-03-06 13:11
    Bruce,
    I am very interested in seeing how the UNL2x03 is able to do bi-polar. Sadly, the PDF does seem to come up. Is the link broken?

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    "When all think alike, no one is thinking very much.' - Walter Lippmann (1889-1974)

    ······································································ Warm regards,····· G. Herzog [noparse][[/noparse]·黃鶴 ]·in Taiwan
  • Bruce BatesBruce Bates Posts: 3,045
    edited 2006-03-06 13:21
    George -

    I'm not sure what link you mean. I attached the PDF to the message above. I just re-downloaded it from that message, and it downloads fine, in about 8 seconds at broadband speed. What am I missing?

    Regards

    Bruce Bates

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  • Chris SavageChris Savage Parallax Engineering Posts: 14,406
    edited 2006-03-06 15:29
    For Bi-Polar Stepper Motors you would typically use a push-pull type driver, such as the L293D that we have on our Professional Development Board.· The ULN2003/2803 chips are best suited to Unipolar Stepper Motors.

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    Chris Savage
    Parallax Tech Support
    csavage@parallax.com
  • LoopyBytelooseLoopyByteloose Posts: 12,537
    edited 2006-03-07 15:27
    I cannot seem to download the PDF.

    I have read that you can use a Unipolar stepper in a bipolar mode by selection of appropriate coils, but I was thinking that going the other directions might be impossilbe.

    I thought the PDF you posted might clarify. I just don't see how you can 'push-pull' the ULN2X03 chips under any circumstances.

    The L293D is doable, but a smaller version of the L298.

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    "When all think alike, no one is thinking very much.' - Walter Lippmann (1889-1974)

    ······································································ Warm regards,····· G. Herzog [noparse][[/noparse]·黃鶴 ]·in Taiwan
  • JavalinJavalin Posts: 892
    edited 2006-03-08 13:09
    Kramer,

    Try getting the PDF from the source:

    http://www.parallax.com/detail.asp?product_id=27964

    James
  • LoopyBytelooseLoopyByteloose Posts: 12,537
    edited 2006-03-08 13:42
    Well I have been doing a little homework while I was waiting.

    5 Wire Uni-polar are likely to remain uni-polar forever - they share one common wire to all coils and it can't be undone

    4 Wire Bi-polar steppers are likely to remain bi-polar as you cannot combine them in any meaningful way.

    6 Wire Uni-power can be driven like 4 Wire Bi-polar because of the two separate banks of coils.· There are two ways to do so.

    8 Wire -· I just don't know. Both these and the 6 wire seem to have 4 coils.· So I am guessing that you can go either way.

    Additionally some industrial steppers have internal diodes for logic and protection.· These may add to the limiting of adaption.


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    "When all think alike, no one is thinking very much.' - Walter Lippmann (1889-1974)

    ······································································ Warm regards,····· G. Herzog [noparse][[/noparse]·黃鶴 ]·in Taiwan

    Post Edited (Kramer) : 3/8/2006 2:48:31 PM GMT
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