MOSFET for stepper motor

Discussion in 'General Electronics Chat' started by Adamko, Oct 30, 2012.

  1. Adamko

    Thread Starter New Member

    Oct 30, 2012

    I have a problem i do not know which transistors to use for my application.
    I have unipolar stepper motor:
    4 coils (9 wires, two wires pro coil and one ground)
    R = 5Ω (pro coil)
    Imax.= 1 A (pro coil)
    switching frequency < 50kHz
    power supply = 5 V,

    I try to realize a circuit with transistors TIP122, but they were to slow. Motor was working only at low frequency till 2 KHz pro step (picture up). I think i need to use MOSFET-transistors. The problem is that i do not know which one to use. Does anyone has experience with similar things? I do not know too how to design a circuit. Can i connect gate directly to the microcontroller, Source to power supply ( 5V power supply from an old computer source) and Drain to ground or do i have to add some safety diodes and resistors?

    I would appreciate every kind of help!

  2. tracecom

    AAC Fanatic!

    Apr 16, 2010
    I built this about 15 months ago and it worked well.

    ETA: Although I didn't really try to run the stepper fast.
    Last edited: Oct 30, 2012
  3. Adamko

    Thread Starter New Member

    Oct 30, 2012
    One question more: Direction of diodes on source of transistors? I thing that in example U posted no current will flow through transistor,or? Why U put diodes there anyway?
    Thanks for your help!