How Plug In Power works

Take a look at a typical electret microphone pre-amplifier. This electronic circuit is always (has to be!) very close to the microphone capsule:

The (blue) transistor circuit MUST be very close to the microphone element. But the (red) resistor R, the capacitor C and the battery can be moved far away! When these components are placed inside the recorder, that is Plug In Power! - and nothing else! It means that the resistor, the capacitor, and the battery that the microphone needs are placed inside the recorder/video, instead of in the microphone body! Most Walkmans and MD's have this arrangement nowadays, which means that you can power a microphone from the microphone input - without a battery of its own.

This is Plug In Power:

Summary: Using Plug In Power means that you don't have to think about an extra power box to the microphone or about microphone batteries! If the recorder/video runs, the microphone will run too. The only disadvantage of using Plug In Power, is that the voltage at the point V. (above) is too low to drive an efficient active filter inside the microphone body.

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