Joystick control potentiometer resistance: what range?

Discussion in 'General Electronics Chat' started by Alec_t, May 1, 2016.

  1. Alec_t

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    For a normal rotary potentiometer the resistance track and wiper travel each cover an angular range of about 300°. For a joystick, however, the wiper travel is only about 60°.
    Datasheets for joysticks that I've read so far give the pot value as, say, 10kΩ but don't make it clear whether that is the resistance over 60° or 300°. Here's the situation :
    Pots.PNG
    For the joystick, if the spec says "10k" does that mean the resistance range is 10k from a to b or from c to d ? (The latter would imply a resistance of ~ 50k from a to b).
     
  2. bertus

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  3. jpanhalt

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    Interesting question and hard to find the answer. I selected a commmercial quality joystick at DigiKey:
    upload_2016-5-1_6-2-15.png

    Source: http://media.digikey.com/pdf/Data Sheets/APEM Components PDFs/M31L081P.pdf

    My reading of that is that the pot itself is 5kΩ, i.e., a to b. So the resistance range (c to d) would be less. Cheaper joysticks (like the Parallax version) have even less information, but my suspicion is that the resistance rating is the rating for the potentiomenter itself that Parallax buys, not the range of resistance based on the actual mechanical range of motion. In other words, the rating probably means the same in both cost classes.

    John
     
  4. Alec_t

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    Thanks guys. I didn't find anything definitive in the post #2 link, but the above spec (and I'm not sure I've understood the 'electrical travel' bit fully) does suggest that the useful resistance range is less than the total pot value. I guess it's cheaper for the joystick manufacturer to use off-the-shelf pots than to have them specially made with the resistive track covering only a small angular range.
     
  5. bertus

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    Hello,

    You might have noticed that some joysticks have the potentiometer on a movable holder.
    That is to "calibrate" the center position.

    Bertus
     
  6. Alec_t

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    I can see that would be useful for some applications.
     
  7. DNA Robotics

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    Jun 13, 2014
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    OMG!
    Do NOT use a joystick unless you are a trained professional.
    If your opponent is better than you are, you could be shot down and / or KILLED!
    :D
     
    Last edited: May 2, 2016
  8. Alec_t

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    LOL. Don't think that's likely though: I'm not a gamer ;).
     
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