Home Brew Artikel - Micophone Compressor (For ELECTRET MICROPHONE)

The circuit shown is that of a "microphone compressor", i.e., an amplifier circuit which exhibits gain, but continually adjusts that gain to maintain a reasonably constant amplitude output signal, regardless of the amount of signal coming from the microphone itself.





Its uses are many, in the audio field, probably the most common, is in a broadcasting studio (etc) here a constant audio line level is required regardless of whether the announcer's voice be oud or soft. This simple circuit is easy to "get working" and uses readily available components. The circuit is based on a well-known design, but with modifications: I have chosen for the active circuit element to be a "single supply" Op-Amp LM324, as opposed to the more conventional ypes which require both a +ve and -ve supply voltage for their operation. This means that this ircuit can be of miniaturized construction and may be incorporated into the microphone body itself, it requires only one extra "core" within the microphone cable to run a +12 volt dc supply for the electronics.