a slightly different type of condenser microphone that has a diaphragm made of a charged plastic material tightly stretched over a circular ring
A microphone design similar to that of condenser mics except utilising a permanent electrical charge, thus eliminating the need for an external polarising voltage (acronym for electricity + magnet). However an internal JFET amplifier is needed to overcome its extremely high output impedance, which requires (less) external power.
A condenser microphone which, instead of employing an external high voltage power source, relies on permanently polarized plates, a low voltage power supply, and internal preamp.
This device works similarly to the condenser microphone, but the condenser plate is made from an "electret" material to provide the polarizing voltage. It consists of a very light diaphragm (moving plate) and back plate (stationary or static plate) and has a permanent charge implanted into it. The principle of operation is that sound waves moving the diaphragm cause the capacitance between it and the back plate to change synchronously which induces an AC voltage on the back plate. The advantage of an electret microphone is that it not only has a higher capacity, but is also cheaper than other types of microphones.
The most common microphone for new telephones. Electret microphones require an external power supply.
A type of condenser microphone that does not require a polarizing voltage. It contains a capacitor-like device, and electret which has a permanent electric change. With a pre amp, the impedance of the electret microphone is very low. The audio pick up pattern is omni-directional.
An electret microphone is a relatively new type of condenser microphone, which eliminates the need for a high-voltage bias supply by using a permanently-charged material.
