A low-noise transistor microphone amplifier

A microphone amplifier is described which possesses good noise characteristics at all gain settings and the capability of handling large input signals without appreciable distortion at low gain settings. A single potentiometer is used as the gain control to 1) vary the negative feedback to provide high overload capability at low gain, and 2) attenuate the output to provide a minimum gain of zero. The circuit is developed from a two-transistor building block.