24vdc Foot Pedal Speed Control

Discussion in 'The Projects Forum' started by fishaholic, Sep 10, 2015.

  1. fishaholic

    Thread Starter New Member

    Sep 10, 2015
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    speed & direction control.jpg 24VDC GEARMOTOR.jpg Greetings,
    I am attempting to control the speed and direction of a small 24 vdc gearmotor, (.3A) using a foot pedal.
    I have a pwm speed/direction power supply/controller that utilizes a small potentiometer knob and a dpdt switch to handle both the speed and direction.
    The pot is rated at 100kohms
    My question is: How do I incorporate a foot control into the mix?
    I'd like to be able to switch between foot/knob control, but the foot pedal mfgr. says their 100k foot pedals won't handle anything above 2 watts, and I would burn it up by connecting it directly to the motor.
    Any advice would be much appreciated.
     
  2. alfacliff

    Well-Known Member

    Dec 13, 2013
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    use the 100k pot in the foot control instead of the 100k pot that came with the motor control, the motor current does not flow through the 100k pot.
     
  3. Kermit2

    AAC Fanatic!

    Feb 5, 2010
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    It is not likely that the pot already on the board is directly controlling the motor. It does not look big enough to handle more than 1 watt itself.
    What is written on it? Can you get any info off of it?
    You should be able to switch between your foot pedal pot and the one on the board with no worries.
     
  4. fishaholic

    Thread Starter New Member

    Sep 10, 2015
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    Thank you for the response.
    That would mean I would have no control with the knob, correct?
    If so, that will not work for my particular application.
    I need to utilize the knob control to run the motor at a constant low speed for a few hours at a time.
    Sorry I didn't mention that.
     
  5. fishaholic

    Thread Starter New Member

    Sep 10, 2015
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    Thank you sir for that response.
    The controller is rated at 80 watts and 3 amps
    I know this can be done, as I have seen it in operation. (that info. is available at a price, which is above my budget)
    Just need to find the correct components and wiring application
     
  6. fishaholic

    Thread Starter New Member

    Sep 10, 2015
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    I also found this wiring diagram on the supplier's website.
    Hope this helps.

    Thank you
     
  7. mcgyvr

    AAC Fanatic!

    Oct 15, 2009
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    You just need to add another SPDT switch that "switches" in either the foot pedal pot or the knob pot.
    Desolder the knob pot and remote mount it..
    pardon my napkin sketch..
    pwm is the board.. the "k's" are each knob (pot)

    pwmknobs.jpg
     
  8. ScottWang

    Moderator

    Aug 23, 2012
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    Wow, I can't believe that you didn't use any circuit software or paint to draw the circuit?
     
  9. fishaholic

    Thread Starter New Member

    Sep 10, 2015
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    Thank you mcgyvr.
    I just have a couple questions regarding your diagram. ( I don't mind the napkin sketch, I'm a simple guy)
    1 - Why do I need to desolder the board mounted pot and remote locate it?
    2 - In your diagram does it matter which polarity gets attached to the wiper side of the pot?
    3 - Will the foot pedal still be able to carry the load of the motor?

    Thanks you.
     
  10. mcgyvr

    AAC Fanatic!

    Oct 15, 2009
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    #1- you need to be able to tap into each pot so they are isolated.. You could just wire the other one in parallel but you would loose the total range that way..
    Basically you need to get at the "in" and "out" of the pot to duplicate my napkin sketch..
    As is now the one pot is across those 2 circles/connection points on your board.. You need to not have that.. so desoldering is the easiest way to go..
    #2-No.. pots are non-polarized
    #3-I HIGHLY doubt that motor current is actually running through the pot.. Could be but I'd suspect its more like this schematic http://3.bp.blogspot.com/-8ubJ4AHNR...eom8SClzY/s1600/PWM+motor+control+circuit.png where the pot is not part of the motor current path..
     
    Last edited: Sep 10, 2015
  11. mcgyvr

    AAC Fanatic!

    Oct 15, 2009
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    Sometimes napkins/pictures are just fun.. :)
    Its actually a post it note though... My napkins are brown color and have taco sauce on them..
     
  12. ScottWang

    Moderator

    Aug 23, 2012
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    After ate some foods and use the paper draw the circuit, but the circuit is too simple, I still can't figure out what you trying to do from the circuit?
     
  13. fishaholic

    Thread Starter New Member

    Sep 10, 2015
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    Thanks again Mac, I will investigate the situation this evening.
    As I am not an electronics guru by any means, (I don't even own a soldering iron) I may need to get an additional taco-sauced schematic if that's at all possible.
    I have yet to even try out the speed/direction controller, but I WILL give it the acid test tonight.
    After all, the parts were relatively cheap, (less than $20)
    I appreciate the input.
     
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