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interface isolated speaker and microphone to industrial intercommunicator

Discussion in 'Electronics Homework Help' started by scarebyte, Aug 22, 2012.

  1. scarebyte

    scarebyte

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    Aug 22, 2012
    Hi,
    I have an industrial intercommunicator, that have a micro/speaker in one device. When the talk switch (see image) is closed it acts as phone when is open as speaker. I want to connect it to separated microphone and speaker, also use 2 new switch and new potentiometer? what device is best suited for this task? maybe a conmutator that change speaker-phone when the new switch talk changes? There could be a problem with the impedances?
    I have no problems connecting the new 2 switchs, I can connect it in parallel, but how connect the new potentiometer without remove the one in the intercommunicator?

    The intercommunicator is Atkinson Dynamics brand.

    Thanks.
     

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  2. (*steve*)

    (*steve*) ¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd Moderator

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    Jan 21, 2010
    Firstly, you could do this if your switch had an extra set of contacts. It would need to be DPDT, with one pole being used as the PTT and the other to switch one wire between either of the devices (speaker or mic)

    But you may face a problem. It is almost certain that the circuit expects to see the speaker as the mic and the input impedance and gain may not suit another typ of microphone.

    As for the new pot, well, you could replace the old one, but it may be difficult to have two of them.
     
  3. scarebyte

    scarebyte

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    0
    Aug 22, 2012
    Hi, thanks for your repply. The switch doesn't have any aditional contact. In case I face the problem with the impedances, how can I fix that?

    Thanks.
     
  4. (*steve*)

    (*steve*) ¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd Moderator

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    Jan 21, 2010

    With a small buffer circuit designed for both the microphone you have and the input impedance of the comms device.

    It's hard to be more specific. You need to know more about both.
     
  5. scarebyte

    scarebyte

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    0
    Aug 22, 2012
    Hi, I tried with the conmutator relay. I connected the 24vdc from the talk switch to A1 of the relay and the gnd from the talk swtich to A2. But when power on, the voltage drops from 24vdc to 5vdc. Why happen this?

    Thanks.
     
  6. (*steve*)

    (*steve*) ¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd Moderator

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    Jan 21, 2010
    Can we see a diagram of what you connected? It's very hard to tell from that explanation.

    Also describe the "conmutator relay" and what it's connections are.
     
  7. scarebyte

    scarebyte

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    0
    Aug 22, 2012
    I fix the voltage drop using the 24vdc given by the transformer. Now I'm using a conmutator.
    There are 2 wires that go to the speaker/microphone of the intercomunnicator. One is black and the other white. The black wire is connected to ground. Using a multimeter appears the white is connected also a ground. These 2 cables are the only ones connected to the speaker/microphone. Why the white and black are connected to ground?. Because my idea was connect the black and white to the speaker and conmutate to the microphone. But the speaker and micrphone have 3 cables, audio +, audio - and ground.


    Regards
     
  8. (*steve*)

    (*steve*) ¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd Moderator

    25,174
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    Jan 21, 2010
    I still have no idea what this is.

    sounds reasonable.

    sounds quite unlikely.

    I can assure you that they are almost certainly not.

    What range did you have the multimeter set on and did you have the speaker connected when you made the measurements?

    Again, that word "conmutate"

    Even if you mean "commutate", I can't see how this fits here.
     
  9. scarebyte

    scarebyte

    15
    0
    Aug 22, 2012
    I test continuity with the intercomm. power off, the multimeter was in continuity mode only, didnt check any range.

    The relay have this form:
    1 2 3 4
    |../ |../.. |../ |../
    I....|......|....|
    0 . 5

    For energize the coil im using the talk swtich connected to 24dv that comes from the transformer. In one contactor, in the common pins (0 and 5) i connected the white and black wires that comes from the micro/speaker and in the oposite pins (1, 3) is connected the speaker wires and in 2 and 4 the microphone wires.

    So when the talk switch is used it will activate the external microphone, in its normal state the speaker is active.
    My problem is that im not sure how connect the white and black wires.

    Regards
     
    Last edited: Aug 26, 2012
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