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Stepper motor just vibrates and gets hot

  1. Dec 14, 2009 #1
    I have a 5-wire unipolar J835L. I have not been able to find a data sheet on it, but I have found this diagram:


    also, the motor has the following information printed on its label:

    Uni-Polar, Bi-Filar
    120 Ohms
    7.5° per step or 48 full steps per revolution
    JARL J835L PM 24P

    I have connected a ULN2003A ("focus.ti.com/lit/ds/symlink/uln2003a.pdf"[/URL]) between my uC and the motor like this:


    B = blue wire
    P = purple wire
    Y = yellow wire
    O = orange wire
    W = white wire

    I have tried driving the circuit in these two orders:

    Step POBY and PYBO
    1 1000 1000
    2 0100 0100
    3 0010 0010
    4 0001 0001
    5 1000 1000
    . . .
    . . .

    Where 1 has been verified to be 10v and 0 is 0v. I set each step and then wait for .1ms. The motor then just vibrates. Can anyone give me a pointer?

    Last edited by a moderator: Apr 24, 2017
  2. jcsd
  3. Dec 14, 2009 #2


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    Science Advisor

    That delay of 0.1 mS seems too fast.

    Just for a test, try 500 mS.
  4. Dec 14, 2009 #3
    Could be a problem with timings or the run sequence. It could be going forward, then next step makes it go backwards.
  5. Dec 15, 2009 #4
    That was it! Thank you :)
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