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One VR adjust two channel volume.

Discussion in 'Electronic Design' started by Boki, Sep 30, 2005.

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  1. Boki

    Boki Guest

    Hi All,
    How to implement one variable resistor to control two channel
    volume?

    Best regards,
    Boki.
     
  2. Jim Thompson

    Jim Thompson Guest

    One variable resistor to control two channel BALANCE, easy, "one
    variable resistor to control two channel volume", not so easy.

    But lots of different ways... perhaps the easiest: use a single pot,
    A/D, control two digital pots.

    ...Jim Thompson
     
  3. Pooh Bear

    Pooh Bear Guest

    Oh come on now !

    A dual pot is simpler ! It can all be done 'analoguely'. ;-)

    If you want to do it with a single pot, then you digitise the pot setting
    and use it send a control word to your DAC.

    Graham
     
  4. Boki

    Boki Guest

    Please advice TI 1742 can do that or not.

    Thank you very much.
     
  5. Boki

    Boki Guest

    It seems that will affect the AV output sepc? right?
     
  6. Boki

    Boki Guest

    use audio ampilifier is cheaper or opamp by myself is cheaper?

    Thank you very much.

    Best regards,
    Boki.
     
  7. Pooh Bear

    Pooh Bear Guest

    Yes it has a built-in digitally controlled attenuator. You may not
    have a spare ADC to read a pot though.

    Using a simple 'volume control' arrangement may be a lot simpler
    though !

    I hope you know how to do that !

    Graham
     
  8. Boki

    Boki Guest

    Ya, I got it.

    Coudl you please advice:

    1. the cheapest AD for this application.
    2. Does that effect the AV output spec? is that alright?

    Best regards,
    Boki.
     
  9. Mac

    Mac Guest

    Do you literally mean "variable resistor," or is it a potentiometer with a
    wiper? I assume you mean potentiometer.

    In any case, you can use a Voltage controlled amplifier. For example the
    SSM2164.

    The variable resistor would be used to set the control Voltage for the
    SSM2164. You will probably need to buffer the Voltage as the control
    inputs on the SSM2165 apparently have a 4k input impedance.

    HTH.

    --Mac
     
  10. Ban

    Ban Guest

    You need a log tapered stereo pot to control 2 channel volume. Or else you
    can use a dual digital pot and up/down push buttons.
     
  11. Pooh Bear

    Pooh Bear Guest

    His DAC has an inbuilt programmable attenuator that can control output volume
    so doesn't really need any extra devices in the signal path.

    Graham
     
  12. Jon

    Jon Guest

    Use 2 analog multipliers. The "variable resistor" could control the dc
    input to the x(y) input to both multipliers. The audio input would go
    to the individual y(x) inputs of the multipliers. This would only work
    well for high level signals. Otherwise, noise would be a problem.
    This is an expensive solution.
     
  13. Mac

    Mac Guest

    Ah. Now I see that there is a relevant history to this question which
    precedes this thread. My apologies.

    --Mac
     
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