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DPDT toggle switch as alternative to H bridge

Discussion in 'General Electronics Discussion' started by hca, Aug 28, 2012.

  1. hca

    hca

    15
    1
    Aug 28, 2012
    Greetings,
    I need to power a 12 V DC motor which can run up to 10 A. Will the use of a dpdt toggle switch (rated at 10 A) be safe to use to control the direction of the motor? My alternative idea is to use a PIC microcontroller to control a dpdt relay h-bridge. What are your thoughts/suggestions?
     
  2. Harald Kapp

    Harald Kapp Moderator Moderator

    9,416
    1,925
    Nov 17, 2011
    If the switch is rated for the current and voltage: yes.
    But you will need
    - either a switch with a center-off position
    - or an additional switch to turn power of.

    Otherwise you can change the direction of rotation, but you can't stop the motor.

    How fast do you have to switch?
     
  3. hca

    hca

    15
    1
    Aug 28, 2012
    Thanks Harald.
    I was thinking of going with an on-off-on switch. Switching speeds are pretty slow, only occasionally using to switch motor direction. But I might need to have PWM, so I can start the motor slowly to avoid a high start up current spike.
     
  4. Harald Kapp

    Harald Kapp Moderator Moderator

    9,416
    1,925
    Nov 17, 2011
    Where's the PWM coming from?
     
  5. hca

    hca

    15
    1
    Aug 28, 2012
    Correct me if I am wrong,
    I was thinking of having a PIC uC generating the PWM signal. This signal would be going into an opto-isolator and this would control the motor speed.
     
  6. Harald Kapp

    Harald Kapp Moderator Moderator

    9,416
    1,925
    Nov 17, 2011
    In that case I suggest you use an H-bridge (see Wikipedia under projects). You can then combine speed control and direction control in one element by selecting which leg of the H-bridge the controller activates with the PWM signal. For stopping the motor you just turn of the PWM.
     
  7. hca

    hca

    15
    1
    Aug 28, 2012
    Many thanks
     
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