Telephone Receiver

Telephone Receiver Points : Telephone Receiver, Theory of Telephone Receiver Operation, The sound reproducer in telephony is called receiver. The receiver does the reverse function of a transmitter. It is a device, which converts electrical energy into sound energy.

The constructional details of the telephone receiver, is shown. It consists of a diaphragm, permanent magnet and windings. When the incoming signal current passes through the windings, magnetic flux is produced. The magnetic flux follows the magnetic path, which consists of the iron path of the permanent magnet, the pole pieces, diaphragm and the two air gaps between the diaphragm and the pole pieces. Thus a varying magnetic pull is produced, which causes the diaphragm to vibrate in accordance with the signal current received and hence produce the sound. The permanent magnet is used to polarize the receiver. The pull on the diaphragm depends upon the magnetic flux density in the air gaps between the diaphragm and the pole pieces. Thus maximum change will be produced when the current changes in the coil. The effects of polarizing the receiver can be explained as follow: