Design, construction and test on a two station simple intercom system

Design, construction and test on a two station simple intercom system

LITERATURE REVIEW

OPERATIONAL PRINCIPLES OF AN INTERCOM SYSTEM

A telephone uses an electric current to convey sound information from our home to that of a friend. When the two parties  are  talking  on  the  telephone,  for  instance,   the telephone company is therefore sending a steady electric current   through   the   phones;   the   two   telephones   are therefore sharing this steady current. Because of these total current sharing, every change in the current through one telephone causes a corresponding change in the current through the other friends telephone or whosoever was communicating. Thus, as one party talks, the current through the other friends telephone fluctuate. A speaker in that telephone   responds   to   these   current   fluctuations   by compressing and rarefying the air. The resulting air pressure fluctuation reproduces the sound of the voice.

The above description holds for a full duplex telephony system with little difference when considering half duplex telephoning (a simple intercommunication system in this case). On the other hand, a simple intercom system whose operation is restricted to a particular destination may derive its current for operation from a power source of about 9volts, 12 volts, etc. depending on the design and designer’s test. It uses current as well when the Intercom is put to use.

An intercom system may consist of two intercom stations linked to each other with a push – to – talk (PTT) switch. The   loudspeakers   act   both   as   loudspeaker   and   as   a microphone or loudspeaker and microphone used separately. [Read more…]