Best transistor switch for stepper motor

Discussion in 'Embedded Systems and Microcontrollers' started by Shorty, Apr 2, 2009.

  1. Shorty

    Thread Starter New Member

    Apr 2, 2009
    3
    0
    Hi, experts!
    What is, in your opinion, the best transistor switch for this app?

    +12V
    |
    |
    |
    LOAD----<-<-<-- Transistor Base----<-<-<---PIC output (max 10-20mA)
    (5-10A)
    (3-4 A may also work)
    |
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    GND

    The load is a stepper motor winding so of course i need 4 switches.
    I am looking at BD679 or BD649, but I'm, open for suggestions.
    I want a clean, simple circuit so darlington transistors are preferred.
     
  2. beenthere

    Retired Moderator

    Apr 20, 2004
    15,815
    282
    We ask that posters not hijack existing threads by placing their questions in the existing flow. Especially when the thread is 2 years old - http://forum.allaboutcircuits.com/showthread.php?t=6168. It can be confusing as to which question is being replied to.

    Perhaps you might think of a current limiting resistor in the base circuit.
     
  3. Shorty

    Thread Starter New Member

    Apr 2, 2009
    3
    0
    I am very sorry I did that. Can I move it to a new thread or post it again to a new thread?

    Anyway, yes, a resistor limits base current to 10mA.
    Transistor idea?
     
  4. thatoneguy

    AAC Fanatic!

    Feb 19, 2009
    6,357
    718
    Which type of stepper?

    Sometimes an IC like the SN754410 (quad half H-Bridge driver, upgraded L293D) is a simpler solution for small steppers, for the currents you need, an IC driving the transistors also frees up some pins on the PIC.
     
  5. hgmjr

    Moderator

    Jan 28, 2005
    9,030
    214
    As has been pointed out already, you have failed to tell us which type of stepper motor you are using. This information goes to the heart of the solution you request.

    Knowing whether it is a bipolar or a unipolar will help us help you.

    hgmjr
     
  6. Shorty

    Thread Starter New Member

    Apr 2, 2009
    3
    0
    Thanks ! :)
     
  7. gunaynail271

    New Member

    Oct 4, 2006
    1
    0
    bdx53 or tip122
     
  8. atferrari

    AAC Fanatic!

    Jan 6, 2004
    2,652
    767
    I did my first tests using small steppers and the 2N2222 was enough.

    With a Darlington transistor, your 10 mA base current could be much more than what you need. It all depends what stepper (thus what transistor) you use.

    Restating the obvious.

    Buena suerte.
     
    Last edited: May 1, 2009
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