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Noob question regarding 555-DPDT relay-Motor

Discussion in 'Sensors and Actuators' started by Blakpawn, Jun 18, 2017.

  1. Blakpawn

    Blakpawn

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    0
    Jun 18, 2017
    Hi,

    Flushed with the success of building an Adafruit circuit thing (I just followed instructions), I would like to try and build something of my own devising...

    I would like to create a 'thing' which allows a DC motor to spin in 1 direction for say 20 seconds, then reverse for 20 seconds, and then start all over without any manual intervention. All from something like a couple of AA batteries.

    My naive plan is to use a 555 timer chip to drive a DPDT relay which drives the motor. Can anyone tell me if this is likely to work or if I should be adopting a completely different approach please? I'm really new to this, although I do have very rudimentary skills V=IR I think??

    Thank you - Richard.
     
  2. BobK

    BobK

    7,642
    1,662
    Jan 5, 2010
    That could work if accuracy of the timing is not that important.

    Bob
     
  3. Irv

    Irv

    112
    30
    Jun 7, 2017
    Yes. The 555 would work, with a few extra parts.
    Basically what you want to do is modify a circuit that flashes an LED
    into a circuit that drives a relay.
    Should be able to find enough info here: http://www.555-timer-circuits.com/
     
  4. Bluejets

    Bluejets

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    712
    Oct 5, 2014
    "talkingelectronics" have a free book with many 555 circuits and animations and explanation on each.
     
  5. Blakpawn

    Blakpawn

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    0
    Jun 18, 2017
    Thank you for your advice, the timing doesn't have to be accurate to the millisecond, but I would like it to be accurate to within a second. The 2 web site links I hadn't found so thank you for that, much reading to do now. Happy wiring.
     
  6. Alec_t

    Alec_t

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    712
    Jul 7, 2015
    As your motor is a low power one (since it runs from AA cells) you should be able to get away with reversing it 'instantly', but be aware that it is good practice normally to allow a motor to come to a stop before changing its direction of rotation.
     
  7. AnalogKid

    AnalogKid

    2,305
    648
    Jun 10, 2015
    If the motor current is low enough, then two CMOS 555s can form an H-bridge and drive the motor directly, eliminating the battery power wasted in the relay coil.

    ak
     
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