Home

Simple Intercom Circuits

An intercom has means,  an electronic communications system intended for limited or private dialogue, direction, collaboration or announcements. Intercoms can be portable or mounted permanently in buildings and vehicles.

Permanent intercoms installed in buildings are generally composed of fixed microphone/speaker units which connect to a central control panel by wires. A small home intercom might connect a few rooms in a house. Larger systems might connect all of the rooms in a school or hospital to a central office. Intercoms in larger buildings often function as public address systems, capable of broadcasting announcements.

 

Figure 1 below is the diagram of a simple intercom circuit. This system is consist of two same circuits. One as A side and the other as B side of communication.

The voice that captured by mic condenser A is attenuated to zero by tuning VR 10 K (null signal principle because of 180 deg phase differentiation of emitter and collector c9013 signal), so this signal is almost not heard at side A Loud Speaker. On the other hand, collector signal of side A circuits is transmitted without attenuation to the side B amplifier circuit, so at side B loud speaker the voice is louder than at side A.

Figure 1. Simple Intercom Circuit

Back

Home