Receiver: Alexander Graham Bell was generally credited with the development of this electro magnetic device, which was initially used for both the reception and transmission of speech. |
Essentially it consists of a coil wound over the pole of a permanent magnet and having a steel diaphragm spaced a small distance from the pole of the magnet. When speech currents pass through the coil, the diaphragm will be attracted or repelled corresponding to the sound waves at the transmitting end. |
This style of receiver was in use for many years and only recently has it been displaced by the use of piezo elecric devices in the more modern electronic telephones. |