Telephone Instruments

Telephone Instruments Points : telephone instruments, telephone set TELEPHONE SET The subscriber telephone set contains of the following:
a. Microphone
b. Receiver
c. Switch connections to the telephone system
d. Ringing circuitry
e. Dial network

The instrument, which contains the microphone and the receiver is called handset. The handset is placed on the cradle when the telephone is not in use. In this position it opens the switches and disconnect the handset from the telephone system. An electromagnet, called the ringer is connected to the telephone line on the exchange side, so that a ring can he received from the exchange when it is called. The exchange determines that whether the telephone is idle or busy or initiating a call by monitoring the dc current. A simplified circuit diagram of the telephone set is shown in the figure.