- Published in issue 12/1994 on page 94
Electret microphone for telephone mouthpiece
Although many older telephone sets are electrically and mechanically perfectly sound units, their speech quality is poor compared with that of modern, all-electronic, sets (except the cheap types used in domestic intercoms). The reason for this deficiency is the carbon microphone in the mouthpiece. Here, an up-to-date replacement is discussed for the carbon microphone. It takes the form of an electric microphone and an amplifier with a special band-pass characteristic.