Low noise Mini Electret Microphone PreAmplifier

  • Rajkumar Sharma
  • 34776
  • easy
  • Tested


The single supply microphone pre-amplifier amplifies the output signal of an electret capsule microphone to audio line levels. An op amp is used as a trans-impedance amplifier to convert the output current from the microphone in to a signal level voltage. The circuit works with 9V so it is good choice for battery operated systems.


  • Supply 9V DC
  • Current Approx. 3mA
  • On Board Microphone
  • Very thin and narrow PCB


Parts List





OPA172 Datasheet




  • JensJ

    Thank you for this. Modified it to run on a 5V supply and using another OP-Amp and it works perfectly with those alterations.

    2 years ago
    • Could you let us know what modifications you have done to this circuit and why?

      2 years ago
  • Dan Gonzalez

    the capacitor C5 is well polarized in the diagram, or is it a misprint

    7 months ago
    • Thanks for noticing this fault. We fixed it above in schematic

      7 months ago
  • I want to purchase the above microphone preamp. What is the cost in USD and how do I get it?

    5 months ago
    • Thanks for your interest in this board. Please check your email for more details.

      5 months ago
  • Javier

    Hi! Is it possible to hear some real sound tests? is it possible to get a copy of this mounted for experimental purposes? thanks and good job!! 🙂

    4 months ago
    • I am sorry, all i have for now is the video above, and we don’t have a sample on hand, but we can produce the board in quantity if you are interested.

      4 months ago
  • Phil Stewart

    I’m interested in several of these — more if they perform well.
    How is performance in the presence of RF interference & nearby electrical devices? The PC board is pretty basic — does it require shielding?
    I am interested in either the PC board or assembled device, depending on price. Thanks!

    3 months ago
  • Simon Rung

    How much for an assembled device?
    For now I’m in a prototyping face and i would like to try one of these out.

    3 months ago
    • Sorry, these will have to be produced on order, so our minimum is 10 boards. Will this work for you?

      3 months ago

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