This is the circuit of a simple intercom for personal conversation between two persons. It is a real fun for the children. Condenser Mic is used to pick up sound signals which are amplified by inverting amplifier made of IC 741. The amplified signals are given to a speaker which gives the audible voice. Capacitors C1 and C3 are DC blocking capacitors. Resistor R1 reduces the current to Mic and determines its sensitivity.
Assemble the circuit on the PCB. Two units are required to make the Intercom. Observe polarity of capacitors, Mic and battery snapper. Orient IC in the correct direction. Connect the two units using two long wires (Thin wires) as shown in the diagram.
Connect the ends of the wires to speaker connection points of PCB1. Connect the other ends to Speaker 2 that is kept in the unit 2. Similarly connect another two wires to the speaker connection points of PCB 2 and connect the other ends to Speaker 1 kept in unit 1.
After assembling the circuit, connect battery. Speak in front of Mic. Your voice will be heard in the speaker of the other unit. The circuit has no volume control. Sound output is very clear and is pleasing.

INTERCOM INTERCOM Reviewed by Babar Ali IET on February 18, 2019 Rating: 5

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