I decided to make this circuit so that I could listen to faint noises. It is a simple two-stage transistor amplifier design. The circuit was designed to use the input from a dynamic microphone but I am sure that with some modifications it would be possible to use an electret microphone. The 2N3053 transistors used in the design don’t have a particularly high gain so other types could probably be used as long as they are NPN.
source: eleccircuit.com
source: eleccircuit.com
