drive relay coil directly from reversed polarity motor

Discussion in 'General Electronics Chat' started by Jan Rune, Mar 8, 2014.

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  1. Jan Rune

    Thread Starter Member

    Apr 22, 2008
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    Hi(again),
    I need to trigger the coil on a relay every time a motor is turning in either direction. Is it ok to just connect the relay directly as showed in schematic? My guess is that the motor driver allready are taking care of protecting the rest of circuit and i dont need a suppresion diode. But are there anything else that can go wrong? Any pitfalls?

    Thank you
    Jan Rune

    [​IMG]
     
  2. #12

    Expert

    Nov 30, 2010
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    Looks good to me. I do this all the time with relay driven motors. That doesn't account for protecting your driver, but I think the relay coil is insignificant compared to the motor.
     
  3. Jan Rune

    Thread Starter Member

    Apr 22, 2008
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    Cheers nr.12. that was what i was thinking/hoping.
     
  4. inwo

    Well-Known Member

    Nov 7, 2013
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    Will the motor ever run too slow for coil pull-in voltage?
     
  5. Jan Rune

    Thread Starter Member

    Apr 22, 2008
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    I wish i had the answer to that, but its all greek to me. The motor is in a lock that open closes a door lock. Its rated to 2 amps and just reverse the polarity to lock/unlock.
     
  6. MaxHeadRoom

    Expert

    Jul 18, 2013
    10,509
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    You can't use a suppression diode anyway, because you change polarity.
    What are you using to drive the motor?
    For a door lock, have you considered a magnetic latch solenoid?
    Max.
     
  7. Jan Rune

    Thread Starter Member

    Apr 22, 2008
    17
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    I know, i was thinking about using two relays. Sorry i didnt make it clear in this post as my other one was closed. I am tapping into a system that is taking care of the motor drive. I just want one option that is not there as standard.
     
  8. #12

    Expert

    Nov 30, 2010
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    Oh crap. We just got tricked into an automotive topic. Bad poster!
     
  9. Georacer

    Moderator

    Nov 25, 2009
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