Radio shack electret microphone

Discussion in 'The Projects Forum' started by ricardo7890, Aug 13, 2012.

  1. ricardo7890

    Thread Starter New Member

    Aug 13, 2012
    Does anyone have any experience with the three wire electret microphones radio shack sells. The diagram on the packing seems to suggest its just a regular electret but with an already wired input resistor and a coupling ecapacitor.I can see the resistor as a bulge in the input wire, but i can't see the 10 microfarad capacitor that is supposed to be connected to the negative lead and makes the third wire. Can anyone who has worked with these electrets confirm if this is true
  2. Audioguru

    AAC Fanatic!

    Dec 20, 2007
    Nobody knows what is in the RadioShack mic (even RadioShack doesn't know) because they don't make it.
    It probably does not have the resistor and capacitor.

    Buy a real microphone from a manufacturer.
  3. radiohead

    Senior Member

    May 28, 2009
    That type is called an FET microphone. The bare wire is negative, the red wire is your bias voltage and the white wire is the output. The output should be coupled through the capacitor. Sometimes they are manufactured with the capacitor inside the case.

    An electret microphone is simply a capacitor with a diaphragm for the positive plate that vibrates with sound.
  4. bertus


    Apr 5, 2008
  5. Audioguru

    AAC Fanatic!

    Dec 20, 2007
    As shown by Bertus, all electret mics have a FET impedance converter inside. The mic can have two wires or three wires.