Headphone audio-2 sources-auto select switch

Discussion in 'The Projects Forum' started by Napoleon, Jan 21, 2009.

  1. Napoleon

    Thread Starter Active Member

    Dec 21, 2008
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    0
    Hello everyone!

    I have a little issue that I'm hoping you guys can help solve.

    I use headphones to listen to music from my phone.

    I would like to come up with some sort of automatic switching device that will allow me to use the phone and handheld radio with the one pair of headphones.

    Basically, I will be listening to music, and when the handheld receives audio, the switch will disconnect the phone, and connect the handheld to the headphones.

    That way I can be listening to music, and still be able to monitor/listen incoming audio on the handheld radio.

    So, basically 2 sources of audio, one output (headphones).
    Switch selects the music source as priority, and only switches to handheld audio when there is audio there.

    Notes:
    Perhaps the power for the switch can be obtained from the microphone jack of the handheld radio. I think it has a few volts on one of the pins of that jack.

    It is a regular Midland brand LXT440 model.

    Thanks for the help!!
     
  2. mik3

    Senior Member

    Feb 4, 2008
    4,846
    63
    If you want this to happen automatically, use a comparator to detect which channel starts to play music and then use an analog multiplexer IC to choose which channel will feed the headphones.
     
  3. Napoleon

    Thread Starter Active Member

    Dec 21, 2008
    45
    0
    Ok, using your suggestion and a quick search, I found this:

    MAX4765 - dual SPDT analog switch qith built in comparator and shunt switch.

    http://www.chipcatalog.com/Doc/D5DC74D51F228C707C0CD589BA93DE0B.pdf
    Page 8


    Would that be a good fit for what I'm trying to accomplish here ?
    My only concern is the package.
    Is there something like that in a through-hole package ?

    Thanks!
     
  4. mik3

    Senior Member

    Feb 4, 2008
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    63
    Yes, it looks good for what you need. If you look at page 8 you will see a diagram of what you want to do. I have never used such IC so I don't know if they exist in DIP packages. Search more.:)
     
  5. Napoleon

    Thread Starter Active Member

    Dec 21, 2008
    45
    0
    Yeah, I saw page 8.
    I referenced it in my post above, with the PDF link.

    The comparator would be wired a little different I guess.
    Instead of a mute switch, its output would be used to control the switch, and the input would be the audio source from the handheld radio.

    I think...

    :confused:
     
  6. Napoleon

    Thread Starter Active Member

    Dec 21, 2008
    45
    0
    Would there be a way to do this with a passive circuit somehow ?
     
  7. mik3

    Senior Member

    Feb 4, 2008
    4,846
    63
    A passive circuit contains only resistors, capacitors etc but not switching devices, so the answer is no.
     
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