How to wire pot with rotary switch?

Discussion in 'General Electronics Chat' started by TheLaw, May 30, 2011.

  1. TheLaw

    Thread Starter Member

    Sep 2, 2010
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    Hello,

    I have a quick question (I hope), about wiring a dual gange potentiometer that has a built-in rotary SPST switch.

    I do not need the included switch. I want it to function as a normal potentiometer. How do I get it to do so? Do I permanently bridge the two SW (switch) lugs?

    It's a Bourns "PTR" panel mount potentiometer. Here's the diagram:

    [​IMG]

    Thanks.
     
  2. gerty

    AAC Fanatic!

    Aug 30, 2007
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    If you don't need the switch, just ignore those terminals.
     
  3. KJ6EAD

    Senior Member

    Apr 30, 2011
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    The PTD902 is pin compatible with the PTR902 and doesn't include the switch.
    http://www.bourns.com/data/global/pdfs/PTD90.pdf

    If the switch is used by an existing circuit and you want it permanently closed, you can solder a jumper on it after installing it.
     
    Last edited: May 31, 2011
  4. TheLaw

    Thread Starter Member

    Sep 2, 2010
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    Just completely ignore them?
     
  5. TheLaw

    Thread Starter Member

    Sep 2, 2010
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    I would, but I'm ordering off Mouser and they don't carry PTD in 10k
     
  6. gerty

    AAC Fanatic!

    Aug 30, 2007
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    If you don't need them, do not connect them.
     
  7. KJ6EAD

    Senior Member

    Apr 30, 2011
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    http://www.mouser.com/Passive-Components/Potentiometers-Rheostats/Potentiometers/_/N-5g9h?P=1z0vkp2&Keyword=ptd902&FS=True

    I saw 7 10k models listed, 3 stocked 4 non-stocked. You must want an unusual combination of features.

    You seem to be thinking that there's some electrical connection between the switch and the potentiometers; there isn't. The only connection is mechanical; they're on the same shaft so the switch gets closed as the wipers on the potentiometer wafers start to move away from one end of their travel. Using the PTR902 only as a potentiometer would be unusual because of the detent at one end of the rotation but you'd get used to it.
     
    Last edited: May 31, 2011
  8. gerty

    AAC Fanatic!

    Aug 30, 2007
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    It sounds like he already has the pot and is just concerened about what to do with the switch contacts.
     
  9. TheLaw

    Thread Starter Member

    Sep 2, 2010
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    Wow I'm an idiot. Someone missed those. I expected the pictures to be more alike.

    PTD902______ PTR902
    [​IMG] [​IMG]


    Just making dumb assumptions again. I did NOT buy the pot yet. Thanks for the heads up. I'll go with the PTD
     
  10. KJ6EAD

    Senior Member

    Apr 30, 2011
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    Don't forget to specify all options per the link in post #3 to create the correct part number.
     
  11. TheLaw

    Thread Starter Member

    Sep 2, 2010
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    Thanks. I got what I needed.
     
  12. TheLaw

    Thread Starter Member

    Sep 2, 2010
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    I also have a subowoofer I want to control the volume for. Can I use a 4-gange pot and ignore one gange?
     
  13. SgtWookie

    Expert

    Jul 17, 2007
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    1,728
    I suppose you could do that, but doesn't the subwoofer output come as a combination of left and right outputs?

    Perhaps you should explain more about the circuit you're connecting this pot up to.

    You'll want audio taper pots for volume control.

    Keep in mind that you need to adjust the volume at "line" level, not at the output of your power amplifier. If you try to control the volume from the power amp output, you will fry the pot - and maybe the amp as well.
     
  14. TheLaw

    Thread Starter Member

    Sep 2, 2010
    228
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    Ah right. I have a board that actively combines the two L + R channels for the subwoofer and preamps the signal. It has 4 potentiometers that control volume, phase, crossover freq. etc. I will use the volume pot that the board has. But I would like a "master volume control" that controls the two L + R channels, as well as the subwoofer in one dial.

    Usually I put my potentiometers AFTER the buffer/preamp, where there is only one channel (because the signals have been combined).

    One question regarding running two potentiometers on the same signal. It's okay to do so, right? I bought the sub preamp/combiner board off eBay and it came with 100K pots. (Printed = "A100k") So I'd like to use the one on the board to control just the subwoofer's volume, and then I'd also like to use the master potentiometer to control the subwoofer and the satellites.

    Any ideas on the best place to wire in the potentiometer? Can I attach one gange of the 4 gange pot directly to the legs of the existing potentiometer on the preamp board?

    Thanks.
     
  15. TheLaw

    Thread Starter Member

    Sep 2, 2010
    228
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    Or should I just wire it into the output terminal block...somehow?
     
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