This is an easy to construct dual-stage microphone pre-amplifier. The project can be used as a sound sensor or microphone pre-amplifier. The 1st op-amp pre-amplify the very low-level signal coming from the condenser microphone and 2nd op-amp provides more boost to the audio signal. The pre-amplifier is an important building block for many audio communication systems and sound sensors. The circuit has been built around OPAMP LM358. The output signal level is dependent on the input sound level. The maximum peak-to-peak output is 2Vpp.