Audio PreAmplifier

This easy circuit provides good gain to weak audio signal. Use it in front of an RF oscillator to make an RF transmitter that very sensitive to sound.


This preamp is very simple, and will work under tough conditions. The input impedance is pretty high, so it won't load down electric guitars. It will also amplify microphones. When I have a moment, I'll make some additions that will optimize it for microphones, and also show how to power a condenser microphone.

Source : Circuits for the Hobbyist