Two Way Intercom Circuit

Listing ID #964101

This Two Way Intercom Circuit  provides a simple way by which we can communicate in two ways i.e. send a signal as well as receive a signal. The circuit is build around timer IC555 (IC1) and low power audio amplifier IC386 (IC2). The circuit is designed in two parts. Here the circuit diagram of one part is shown in figure. The output of one unit is given to the input of other unit. The two parts are co`nnected by three way wire connection points. These points are denoted by 'S' for supply, 'O' for output and 'G' for ground.
About the Circuit :

• When switch 'S1' is pressed, IC1 gets triggered. Hence IC1, which is connected in a stable mode, acts as a tone generator or oscillator. These oscillations generated at output pin3 are given to bypass input pin7 of IC2.
• The sound signals generated due to communication are received by condenser mic connected at audio input pin3 of IC2. These signals are amplified by audio amplifier IC2 and the amplified output generated at pin5 is given to Loudspeaker through coupling capacitor C1. We can mute the unit by pressing switch S2.
• The components mentioned in the part list are only for one side. The other side of the unit uses the same components. Hence twice the components mentioned in the part list should be used except power supply. Three Core shielded wire of about 4-10 meters can be used for connections between two units.

Note on IC386 :
As stated earlier, IC386 is a low power audio amplifier IC, which is very inexpensive and widely used. Some of the important features of this IC are :

• Minimum external parts
• Low distortion
• Wide supply voltage range
• Two-way communication, with self-ringing facility.

Power supply :
The circuit requires a regulated DC power supply of 9V. For this, the power supply design is shown in figure. The assembled module of power supply is to be kept inside one intercom hand set.