According to Wikipedia.org, an intercom is a stand-alone electronic communications system intended for limited or private dialogue. Below schematic shows the 2-Wire Intercom . This intercom is powered by 9 Volt batteries which are connected via a two-wire cable. The loudspeakers act both as loudspeaker and as a microphone.

Wiring 2-Wire Intercom Circuit Diagram

Intercom Circuit Parts List:
9V batteries_________2
8 Ohm speakers_____2
C1________________1000uF
C2________________220nF
C3________________220nF
C4________________47pF
C5________________47pF
C6________________1000uF
R1________________1K
R2________________1K
R3________________1K
R4________________1K
R5________________1M
R6________________1M
Q1________________BC558B
Q2________________BC548B
Q3________________BC558B
Q4________________BC548B
S1________________Switch 1
S2________________Switch 2
Audio transformer



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