Shifting a Potentiometers Resistance

Discussion in 'The Projects Forum' started by Murvok, Mar 30, 2016.

  1. Murvok

    Thread Starter New Member

    Mar 29, 2016
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    I need to shift the resistance of my 5k potentiometer as it currently reads 360 ohms over. I'm using this as a throttle for a motor and I'm worried it will try to turn the motor even at zero throttle.
     
  2. blocco a spirale

    AAC Fanatic!

    Jun 18, 2008
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    How is it connected to the motor?

    Where are you measuring 360Ω, or are you saying it measures 5360Ω?
     
    Last edited: Mar 30, 2016
  3. crutschow

    Expert

    Mar 14, 2008
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    The usual request, post your circuit diagram.
     
  4. Murvok

    Thread Starter New Member

    Mar 29, 2016
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    It measures 360 at zero and 5360 at 5k.
     
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  5. blocco a spirale

    AAC Fanatic!

    Jun 18, 2008
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    I don't think there is much you can do except find a better quality pot but even this may not guarantee a fully off position. Another approach may be to add a true OFF position since at very low duty cycles the motor probably won't run but will consume power. Either find a pot with a switch or fit something to the shaft of the existing pot to operate a microswitch at low settings and cut the power. Someone else may have a smarter solution.
     
  6. crutschow

    Expert

    Mar 14, 2008
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    What type of pot is it?
    What's the part number?
    360Ω seems rather high for a 5kΩ pot. I just measured a 1k, single turn panel pot I had and it's only about 2Ω at the end of its travel.
     
  7. Murvok

    Thread Starter New Member

    Mar 29, 2016
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    It is a low end thumb throttle potentiometer. I don't have a part number as it was given to me. I think I am going to order a new one, but I was worried that it will have the same issue.
     
  8. Marcus2012

    Member

    Feb 22, 2015
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    That pot has exceptional tolerances if the taper runs exactly 5K! :) Sorry if this seems like a silly question but are you measuring this in situ or completely disconnected from the circuit?
     
  9. Murvok

    Thread Starter New Member

    Mar 29, 2016
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    Disconnected. I will probably take readings again today.
     
  10. dannyf

    Well-Known Member

    Sep 13, 2015
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    "t measures 360 at zero and 5360 at 5k."

    It is a miracle that a 5k pot is off that precisely.
     
  11. Alec_t

    AAC Fanatic!

    Sep 17, 2013
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    Have you checked that the 'zero Ohms' adjustment trimmer has been set correctly on your meter?
     
  12. wayneh

    Expert

    Sep 9, 2010
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    Just for reference, there are some useful links here. Probably overkill for the present issue.
     
  13. ian field

    Distinguished Member

    Oct 27, 2012
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    You might be able to pre-load the M/S ratio a little by pulling the voltage level on pin 5.

    It may be enough to compensate for the error on the pot.
     
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