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Motor with Speed Controller

Discussion in 'Sensors and Actuators' started by womackpb, Sep 25, 2017.

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  1. womackpb

    womackpb

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    Sep 25, 2017
    Howdy,

    I thought I knew enough about basic electronics to get this project going. Either I don't, or the parts I purchased are bad.

    I'm trying to set up a battery-powered motor with a speed controller. I purchased a 12v battery, a 12v motor, and a speed controller (rated 6-24v and up to 8amps) from Amazon. See exact links below. I purchased the speed controller for its digital display, as I'll need to dial in the speed precisely.

    Hooking up the battery to the motor directly, it worked fine. However, when I put the speed controller in the circuit, it started to smoke and burn up. Am I doing something wrong? Or is that just a cheap controller?

    Battery: https://www.amazon.com/gp/product/B003S1RQ2S/ref=oh_aui_detailpage_o02_s00?ie=UTF8&psc=1
    Controller: https://www.amazon.com/gp/product/B01N4G5I6H/ref=oh_aui_detailpage_o02_s01?ie=UTF8&psc=1
    Motor (12v, 38rpm): https://www.amazon.com/gp/product/B01MXPO095/ref=oh_aui_detailpage_o02_s01?ie=UTF8&psc=1

    Thanks in advance.
     
  2. Alec_t

    Alec_t

    2,788
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    Jul 7, 2015
    Welcome to EP!
    A schematic of how you connected the controller, motor and battery would help us to help you.
    I see nothing in the controller's spec to indicate if it has inbuilt protection from the back-emf that the motor generates at switch-off, and from any commutation voltage spikes. If it doesn't, then external components (as a minimum, a reverse-biased diode across the motor) would be needed to protect the controller.
     
  3. womackpb

    womackpb

    7
    0
    Sep 25, 2017
    Thanks for the quick response. I connected everything according to the controllers wiring diagram (attached). I did leave one thing out - I did connect the battery to the controller first and turned it on, it began to smoke at that point. Could I have damaged it to start without having a load on it?

    Would this controller be better?
    https://www.amazon.com/dp/B073Z7PB5G

    Thanks again.
     

    Attached Files:

  4. Minder

    Minder

    2,948
    623
    Apr 24, 2015
    Usually those controllers are simple 555 based PWM generators, what parts smoked, the power semiconductor(s)?
    What are the motor ratings?
    There are plenty of these controllers on ebay for ~$5.00.
    Also very easy to build one.
    e.g. http://www.discovercircuits.com/DJ-Circuits/simplepwm2.htm
    M.
     
  5. womackpb

    womackpb

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    Sep 25, 2017
    @Minder Not much info on the motor, other than 12v dc. And unfortunately, I'm not sure what part smoked, it was on the back of the circuit board in the enclosure.
     
  6. Alec_t

    Alec_t

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    Jul 7, 2015
    Possible I suppose, but perhaps you were just unlucky and had a faulty controller.
    The linked controller looks to be beefier. I was amused by this bit of its write-up :-
    "This motor speed regulator has power supply reversed connection protection, over-voltage protection and 20A ceramic arc fast-melting fuse. It can be controlled directly by PLC voltage. However, please do not reverse connect the power supply, otherwise, it will cause damage to the generator." :confused:
     
    Last edited: Sep 25, 2017
    womackpb likes this.
  7. womackpb

    womackpb

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    Sep 25, 2017
    @Alec_t - these cheap ones are certainly all from folks where English is a second language. Thanks, I'm going to snag that one and send the other back as "faulty".
     
  8. BobK

    BobK

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    Jan 5, 2010
    Either it is defective, or your connections were wrong.

    Bob
     
  9. womackpb

    womackpb

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    Sep 25, 2017
    @BobK - thanks. I'll accept the wrong connections as a possibility. Glad to know I wasn't crazy for thinking that it should have worked.
     
  10. BobK

    BobK

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    Jan 5, 2010
    Can you hook it up again, without connecting one of the wires to the battery, and take a picture for us?

    Bob
     
  11. womackpb

    womackpb

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    Sep 25, 2017
    I certainly can. I'll do it this evening and post.
     
  12. womackpb

    womackpb

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    0
    Sep 25, 2017
    Funny enough, came back to it this afternoon. Hooked it back up to the battery, no issue. I have the alligator clips on the motor for testing before I solder them. I wonder if one was touching the motor casing yesterday, causing it to short. Is that possible?
     

    Attached Files:

  13. Minder

    Minder

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    Apr 24, 2015
    Operator Error!;)
    M.
     
  14. Bluejets

    Bluejets

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    Oct 5, 2014
    Now that you have that sorted, it may pay to note that the readout is in no way indicative of motor speed as you stated.
    It is a readout of the pulse as a percentage between zero and 100 percent.
    To read motor speed you will need some form of tachometer.
     
  15. BobK

    BobK

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    1,685
    Jan 5, 2010
    And while we are at it, the speed controller is not a speed regulator. If the load on the motor changes, the speed will change without changing the setting on the controller.

    Bob
     
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