Mic circuit for iPhone 4S.

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  • JonathanAnon
    Badcaps Veteran
    • Jul 2012
    • 457
    • Ireland
    #1

    Mic circuit for iPhone 4S.

    Hi guys,

    I am building a little car kit for my iPhone. Right now, I'm working on the mic/input part of the circuit. I bought a euro store iphone handset to see what such a circuit would involve. Below is the circuit for the microphone part of that handset.



    - The push button shorts out the circuit, which answers a call.
    - I think the resistor / capacitor / diode are to filter any voltage spikes from the PB switch or possibly filter the A/C signal from the mic, but I'm unsure. ?
    - The electret mic has a resistance of 2.2K ohms.

    So, if I ignore the push button for answering the call (and just use the button on the phone to answer calls), can I just hook up an electret mic of similar impedance and I'm good to go? As in this:

    Tags: None
    • Agent24
      I see dead caps
      • Oct 2007
      • 4951
      • New Zealand
      #2
      Re: Mic circuit for iPhone 4S.

      You might need the resistor and capacitor at least for biasing the mic properly or such. I would leave them, and the diode in, if you are unsure if they should be there or not. Just omit or disconnect the button if you don't want to use it.
      "Tantalum for the brave, Solid Aluminium for the wise, Wet Electrolytic for the adventurous"
      -David VanHorn

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