MIC Pre-amplifier

  • Rajkumar Sharma
  • 14614
  • moderate
  • Tested


This project is a microphone pre-amplifier based on LM358.


This is easy to construct microphone pre-amplifier project using compact electret condenser microphone. The pre-amplifier is important building block of many audio communication systems. Circuit has been built around Op-Amp LM358.

  • Power supply : 5 to 12 VDC @ 10 mA
  • Output: Gain Approx. 100
  • On-Board electret condenser microphone
  • Header connector for connecting of power supply input and audio output
  • Power-On LED indicator
  • Four mounting holes of 3.2 mm each
  • PCB dimensions 35 mm x 40 mm


Parts List



  • robert

    thanks for this

    3 years ago
  • Caleb

    Could I replace the mic you used with an XLR input? Trying to figure out how to make an adjustable XLR preamp for cameras.

    3 years ago
    • Electronics Lab

      The mic output is in the range of mV and needs a bias resistor R2 in order to work. In addition you can feed a small signal like that directly on C3 and omit R2 resistor so you get an amplified signal on the output.

      3 years ago
  • Sivanand

    LM358 is not a low noise IC, Use of TLO71 / TLO81 would give better low noise response, cheap and easily available.

    3 years ago
  • Pablo

    The foil side of the PCB image has to be mirrored. In that case your logo and the “800A” would be backwards.

    2 months ago
    • I’ve uploaded PCB in PDF file in the downloads above. Thanks

      1 month ago

Leave a Reply to Electronics Lab Cancel reply


By continuing to use the site, you agree to the use of cookies. more info

The cookie settings on this website are set to "allow cookies" to give you the best browsing experience possible. If you continue to use this website without changing your cookie settings or you click "Accept" below then you are consenting to this.