The purpose of this circuit is to amplify the signal of a medium or high impedance microphone, providing at its output a signal capable of driving a power amplifier or other circuit that makes use of this type of signal. The output is approximately 1 Vpp. The power supply may be a battery or a common source with excellent filtration. Consumption is very low. The power may be obtained from the appliance itself with which the preamplifier will work. Transistors equivalents may be used. The microphone cable should be shielded.
