Unipolar Stepper Motor Resistors

Discussion in 'General Electronics Chat' started by stoopkid, Mar 5, 2012.

  1. stoopkid

    Thread Starter Member

    Mar 3, 2011
    136
    1
    I just got a 28BYJ48 stepper motor from ebay. I don't have a ULN2003 yet so I thought I would just test it with four pushbuttons or NPN transistors. The thing is, every URL2003 driver schematic I find have no resistors. It it okay to drive the motor directly off 5v? And when I DO get the ULN2003, do the bases not need to be limited like transistors' normally are?

    Thanks
     
  2. Potato Pudding

    Well-Known Member

    Jun 11, 2010
    684
    92
    The Darlington array ULN2003 that I believe you are referring to has internal bias resistors.

    You might be able to click the motors a bit back and forth but it will not run without pulse sequencing.
     
  3. Felo

    Member

    Feb 20, 2012
    91
    13
    The datasheet states 12v rated voltage I doubt it will move on 5v, ULN's are logic input so no biasing res required.
     
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