Will this small motor and speed control work together?

Discussion in 'Power Electronics' started by harryhh, Sep 24, 2017.

  1. harryhh

    Thread Starter New Member

    Aug 7, 2017
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    0
    Hello folks,

    I want to make a fly fishing fly dryer. Something like the following. It turns the flies at low rpm while the paint, glue, or epoxy dries.
    https://www.amazon.com/Cascade-Cres...UTF8&qid=1506276833&sr=1-4&keywords=fly+dryer

    I was wondering if a PWM motor speed controller like the following could control the speed of the motor I list here.
    https://www.amazon.com/dp/B01H1W79S0/_encoding=UTF8?coliid=I37CADE0MFQAZW&colid=29CRWQ2I67XQM

    https://www.amazon.com/dp/B01KTZXZMK/_encoding=UTF8?coliid=I2HZ3JRYXKK4GO&colid=29CRWQ2I67XQM

    The motor is 30 rpm. I would probably run it between 5 and 15 rpm. Would running the motor at this low speed cause the motor to overheat? Would it be better to purchase the similar 20 rpm motor listed on that same web page?

    The controller has a reverse switch. Would this motor run backward?

    Harry
     
  2. MaxHeadRoom

    Expert

    Jul 18, 2013
    16,385
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    Run the motor at 50% voltage, no need for a controller, do you need reverse for that application, if using just a simple supply, just reverse the motor leads, DPDT switch.
    Max.
     
  3. AlbertHall

    AAC Fanatic!

    Jun 4, 2014
    6,653
    1,557
    If you don't want more than 20RPM, then that would be a better choice of motor.
     
  4. harryhh

    Thread Starter New Member

    Aug 7, 2017
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    0
    Hello Max,

    I don't really need reverse for this application, at least not that I know of. That was more a matter of curiosity and perhaps different use of this motor and controller in the future.

    From my electronics classes decades ago, I remember that on some motors, (AC?) running at a low voltage did not produce the proper back EMF, which allowed too much current and could burn out the motor windings.

    I don't remember too much about how DC motors worked. I vaguely remember that in most, or all cases, you can reverse the voltage and the motor will run in reverse. But, I'm not sure about that. From your answer though, this is probably true in most cases.

    I would like to have a variable speed control. I'm just starting fly tying and am not sure of what rpm would be best. And, best rpm may vary with what is being done at the time . I've seen some dryers that run at 5 rpm, and some at 12 rpm.

    From your answer I see I could do this much more simply but, I think I would like to have an easily variable control if possible. If not, I'll just find a motor around 7 rpm give or take.

    I am a bit concerned with low voltage burning out the motor, but I don't think that applies as much to DC motors as it does to AC. And I can see where PWM might cause no overheating.

    Anyway, should I be able to get reasonable speed control with this motor and PWM controller, with little to worry about overheating?
     
  5. MaxHeadRoom

    Expert

    Jul 18, 2013
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    The factor on overheating a DC motor is overloading it, which is very unlikely with your application, the rpm is virtually relative to the voltage applied.
    You could get any of the simple $5.00 PWM controllers on ebay if you want some control.
    Max.
     
  6. harryhh

    Thread Starter New Member

    Aug 7, 2017
    5
    0
    Thanks Albert,

    For this case of fly drying, I can't see needing more than 15 rpm. But, occasionally I have need for a slow turning motor for this or that and I could temporarily take the motor and controller from this fly dryer. I thought that having a 30 rpm motor might come in handy. But, it really isn't necessary. If this kind of thing works, another motor and controller aren't too expensive.

    Does anyone know if slowing a small DC motor to 1/5 of it stated rpm, using a PWM supply, would cause the motor to run too hot?
     
  7. harryhh

    Thread Starter New Member

    Aug 7, 2017
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    0
    Thanks Max,

    That's sounding good.
     
  8. MaxHeadRoom

    Expert

    Jul 18, 2013
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    No, not unless you lock the rotor!:eek:
    Max.
     
  9. harryhh

    Thread Starter New Member

    Aug 7, 2017
    5
    0
    Okay. Thanks folks.

    It sounds as though I should be able to get away with a 30 rpm motor. At less than $13, if for some reason it doesn't work out, I could learn my lessons and get a more appropriate motor.

    Harry
     
  10. MaxHeadRoom

    Expert

    Jul 18, 2013
    16,385
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    Rated Torque: 12Kg.cm; Rated Current: 0.1A; Reduction Ratio: 1:172;
    12Kg-cm: You still have doubts?:cool:
    Max.
     
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