MIC Pre-amplifier


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

Leave a Reply

This site uses Akismet to reduce spam. Learn how your comment data is processed.