dual source input signal to single speaker

Discussion in 'The Projects Forum' started by jimtxas, May 7, 2012.

  1. jimtxas

    Thread Starter New Member

    May 7, 2012
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    0
    I have a need to create a relay circuit that allows the following:

    2 audio line inputs to 1 audio line input.
    For example, 2 input circuits A and B to a relay.
    Circuit A has a constant signal that's passed to C (the speaker, or amp input)

    when a signal is present on audio Input B, the relay switches to B passing it to C.

    We have a security system that relays phone rings, doorbells, etc. We also have a whole house audio system. I simply want to pass on that signal details from the security system to the whole house audio when/if there is a signal present interrupting any other audio.

    I know there are whole house audio systems that do this natively but do not want to replace and sure i can do this with some sort of relay setup.

    Any recommendations, part numbers that may be needed would be appreciated. i can fire up the soldering iron and put this together with any components required but if there's a device out there that already does this that would be appreciated as well.
     
  2. wayneh

    Expert

    Sep 9, 2010
    12,100
    3,034
    Sorry for all the questions, but we'll need to better understand.

    So currently there is no interconnection at all?

    Do you merely need to MUTE the audio so that you can hear the security system, or do you need to add the audio system in on top of your security system?

    When the security system fires, does it send its signal to one place. I mean, does a phone ring or a doorbell end up in the same audio output?

    How are the two systems powered? Probably independently, both from main power via a wall wart or other transformer.

    On your audio system, does it have multiple inputs, like radio, CD, etc.? And/or does it look like you can get into the circuit? You may to get in between the pre-amp and the power amp.
     
  3. jimtxas

    Thread Starter New Member

    May 7, 2012
    3
    0
    No problem... here's the answers.

    So currently there is no interconnection at all?
    <NO>

    Do you merely need to MUTE the audio so that you can hear the security system, or do you need to add the audio system in on top of your security system?
    <do not need to 'mix' it... simply mute one source and play the other source reverting back to primary when there's no signal from the security system>

    When the security system fires, does it send its signal to one place. I mean, does a phone ring or a doorbell end up in the same audio output?
    <yes... one output>

    How are the two systems powered? Probably independently, both from main power via a wall wart or other transformer.
    <both independently, wall wart>

    On your audio system, does it have multiple inputs, like radio, CD, etc.? And/or does it look like you can get into the circuit? You may to get in between the pre-amp and the power amp.
    <yes, but i do want to go between the preamp-amp which is single source>

    Thanks a million!
     
  4. wayneh

    Expert

    Sep 9, 2010
    12,100
    3,034
    Ok, great. So I imagine a black-box circuit powered by the supply to the audio system, that has two line-level inputs; 1. audio system pre-amp output and 2. security system output. The black-box defaults to #1 (audio) unless a signal is detected on #2 (security). The black-box output will go to the audio amp. Does all this sound right?

    Not sure about existing, off-the-shelf options. I believe what I just described is called an audio mux circuit. I'm sure somebody here will have a good option.
     
  5. #12

    Expert

    Nov 30, 2010
    16,261
    6,770
    I remember something about one microphone having the priority to shut off all other inputs and make itself heard. When I remember what it's called, Ah'll be bach. (Have to go read my book on Sound System Engineering by Don and Carolyn Davis.)

    It's called a priority system. One method uses a compressor with a pre-amp on the senior channel so its amplitude activates the compressor and the other information is compressed into obscurity, and another system uses the switch provided on professional quality microphones to activate relays.

    Any relevance?
     
    Last edited: May 7, 2012
  6. jimtxas

    Thread Starter New Member

    May 7, 2012
    3
    0
    wayneh - your description is great.

    #12- sounds like it would get me there but sounds more complex than i thought may be possible... simply want the black box as wayneh described. audio quality on the 'priority' side is not an issue... on the pass through side it is, which is why i simply want to pass it through...

    Thanks folks!
     
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