Fig.2 Circuit diagram of generic electret microphone capsule biasing
The circuit diagram shows an electret microphone capsule, whose positive terminal is connected to the positive terminal of a 4.7 microfarad electrolytic capacitor. The capacitors negative terminal is connected to the signal conductor of an unbalanced screened cable.
The negative terminal of the microphone capsule is connected to it's casing and to the screen of the unbalanced cable. Also connected to the negative terminal is a 1.5V cell (battery) which is in series with a 1000 ohm resistor to the positive terminal of the microphone.