360 degree potentiometer

Discussion in 'General Electronics Chat' started by Razor Concepts, Aug 7, 2009.

  1. Razor Concepts

    Thread Starter Active Member

    Oct 7, 2008
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    I am wondering whether 360 degree potentiometers exist, where the wiper can be rotated around continuously. I know you can modify normal potentiometers, but those have a dead band where they were not supposed to rotate. I could use two of these but I would rather just have a single potentiometer. Thanks!
     
  2. Ron H

    AAC Fanatic!

    Apr 14, 2005
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    Search for "continuous rotation potentiometer". I got several hits on Google.
     
  3. Razor Concepts

    Thread Starter Active Member

    Oct 7, 2008
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    I tried looking for them, looks like the only manufacturer is ETI systems. But the pricing is a little high ($10+), and the only pot closest to what I want is the EUP1900, with 340 degrees of sensitivity.

    Any ideas about a DIY 360 degree pot?
     
  4. rogs

    Active Member

    Aug 28, 2009
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    What's it got to control?
     
  5. Ron H

    AAC Fanatic!

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    A potentiometer by definition has 3 terminals. One is the wiper. Where would you want the other two terminals connected? 180 degrees apart?
     
  6. bertus

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    Apr 5, 2008
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    Last edited: Oct 31, 2013
  7. ELECTRONERD

    Senior Member

    May 26, 2009
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    There are several digital pots you could use. Just get two tactile switches one for more resistance and one for less resistance and your good to go!
     
  8. Ron H

    AAC Fanatic!

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    How do you emulate continuous rotation (360 degrees) with a digital pot?
     
    Last edited: Sep 4, 2009
  9. beenthere

    Retired Moderator

    Apr 20, 2004
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    Any mechanical pot has to have a dead spot or the wiper would short the end terminals.

    Limitations like that are why things like shaft encoders exist.
     
  10. Ron H

    AAC Fanatic!

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    It is possible to make a continuous rotation pot in which the stator connections are positioned 180 degrees apart. They may even be available off-the-shelf.
     
  11. ELECTRONERD

    Senior Member

    May 26, 2009
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    If you had a 360 degree pot, when you rotate to the maximum value the wiper would keep turning until you would rotate the wiper the opposite direction. Same with a digital pot, you would keep pushing the tactile switch until it wouldn't go any farther; if you kept pressing on the switch if it was at its maximum value, it would have no effect on the resistance until you rotate it the opposite direction. Thereby decreasing the resistance.
     
  12. Ron H

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    That sounds like an ordinary pot to me.
    Imagine a circular resistance element, with taps 180 degrees apart, and a wiper, but with no stops on the rotor.
     
  13. Razor Concepts

    Thread Starter Active Member

    Oct 7, 2008
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    Aha, thats what I'm looking for. I think I will try to DIY that with two pots.
     
  14. rjenkins

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    Nov 6, 2005
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  15. PackratKing

    Well-Known Member

    Jul 13, 2008
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    I see no mention of a precision 10 [ or more ] turn pot............

    I used one of these marvelous contraptions [ clarostat ] in construction of my bench power supply, [ 0 - 24 volt, 4 amp DC ] to enhance control over its output that a "normal" 270 deg. 5K pot wouldn't give.

    The only other option I am familiar with, is a vernier control, which is nothing more than a calibrated gear reducer, and will allow any number of 360 deg. turns to cover the 270 deg. range of that "normal" pot.
     
    Last edited: May 17, 2011
  16. ELECTRONERD

    Senior Member

    May 26, 2009
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    Well, all the normal pots I have stop at the maximum, and minimum points. This would be continuous.
     
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