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What is this type of dial/knob called?

Discussion in 'Electronic Basics' started by Kruminilius W., Jun 24, 2005.

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  1. I'm trying to find the type of dial that you can turn in one direction or
    the other without it stopping (unlike a potentiometer). I have no idea what
    this part is called. Any thoughts?

  2. Andrew Holme

    Andrew Holme Guest

    Do you mean an optical shaft encoder?
  3. I think the optical shaft encoder would do what I want, but they appear to
    be fairly expensive. The device I'm thinking of probably generates some
    type of current when the knob is turned, where the current is proportional
    to the rotation speed. I imagine that they're pretty cheap since I've seen
    them on a variety of cheap electronic devices such as the volume/digial
    tuning knob on radios.
  4. Anything digital generates pulses, (counts) not voltage. Here is an
    example of a low cost encoder used as a manual digital pulse source
    available from Digikey:$FILE/E-33-34.pdf
  5. What you are looking for is a rotational encoder, or gray code encoder.
    There are some low cost ($3 to $6) ones out there but some of them really
    suck (they ar not sturdy, go clack clack clack, and lose contact after a
    while). Optical encoders are much nicer, but incredibly expensive. $125 and
    up. You can get those even with an RS232 interface that returns relative (I
    moved 20 degrees) or absolute values (I am at 24 degrees).


    Low end: Data/ECW1J Series.pdf

    High end: Inc/Web data/MEH30-XXXXP-XX-XX-XX.pdf
  6. (snip)

    The optical encoders are more expensive than the contact types, but
    there are some inexpensive ones available from Digikey.
    $30.00 Inc/Web data/RE20XXXXXXX.pdf
  7. It is called a pot without stops
  8. Alan Adrian

    Alan Adrian Guest

    50 cent electric gear motor with a knob on the end?

  9. colin

    colin Guest

    or a knob with a loose grub screw, i like the cheap 50cent dc motor idea

    Colin =^.^=
  10. me

    me Guest

    There are optical shaft encoders, or cheaper mechanical encoders like are
    used to adjust the display on some computer monitors. There are variable
    capacitors. Also popular is the metal shaft with a knob on it, which moves
    a dial string.

    What exactly are you wanting to use this dial you are looking for for...
  11. Ben Stephens

    Ben Stephens Guest

    What about those wheels in a balled computer mouse??? they do what you
    want to do, but they are fragile.
  12. Kitchen Man

    Kitchen Man Guest

    I don't think so. The poster appears to be looking for a device that
    indicates relative rotation, not absolute position. His example is of
    a digital volume knob on an inexpensive stereo. He's got some good
    answers on that - most intriguing to me is the electric motor
    (generator, actually, since mechanical motion is producing current)
    idea. I think using one of the cheaper optical encoders is probably
    the simplest implementation.
  13. Kitchen Man

    Kitchen Man Guest

    Yep. Those are the optical encoders that have been discussed. I
    think the OP wants a more rugged human interface - something to be
    moved with the fingers?
  14. John Fields

    John Fields Guest

  15. John - KD5YI

    John - KD5YI Guest

    Good luck,
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