Darlington Transistor Array

Discussion in 'The Projects Forum' started by Manmeet Singh, Jun 8, 2009.

  1. Manmeet Singh

    Thread Starter Active Member

    May 21, 2008
    37
    0
    Hey guys I was wondering if someone could shed some light on what this device does? I am looking into using a stepper motor and it seems that this is used to drive it. What is the funcitonailty of the transistor in this set up? Is it amplifying so that a greater current can be used to drive the coils or is it acting as a switch?

    Thanks
     
  2. bertus

    Administrator

    Apr 5, 2008
    15,647
    2,346
    Hello,

    Do you have a schematic?
    Without a schemetic it is a lot of guessing.

    Greetings,
    Bertus
     
  3. Manmeet Singh

    Thread Starter Active Member

    May 21, 2008
    37
    0
    neeevermind i found a good explanation of what they do! how do i take down a post?

    Thanks anyways!
     
  4. Manmeet Singh

    Thread Starter Active Member

    May 21, 2008
    37
    0
    I lied still need some help! So if anyone could explain what this BJT is doing that would be great
    [​IMG][​IMG][​IMG]
     
  5. SgtWookie

    Expert

    Jul 17, 2007
    22,182
    1,728
    The schematic is incorrect.

    Normally, when using the stepper in unipolar mode, +V would be applied at the center tap of each side of the motor's windings (you have them identified as 2 and 5), and a Darlington or power MOSFET would be used to sink current from either end of the winding.

    As things are connected now, D1 is connected backwards (cathode should be on connection 2, anode on connection 1) and Q1 is simply shorting out the winding.
     
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