intercom circuit diagram for room

intercom circuit diagram for room

intercom circuit diagram

intercom circuit diagram

intercom free circuit diagram

intercom circuit diagrams

intercom circuit diagrams

P1____    22K  Log. Potentiometer
R1___     22K  1/4W Resistor
R2,R3____ 100K  1/4W Resistors
R4___     47K  1/4W Resistor
R5_____   2K2 1/4W Resistor (See Notes)
R6_____   6K8 1/4W Resistor
R7________22K  1/2W Carbon or Cermet Trimmer
R8_______ 2K7 1/4W Resistor
C1,C6_____100nF  63V Polyester or Ceramic Capacitors
C2,C3___ _10µF  63V Electrolytic Capacitors
C4________22µF  25V Electrolytic Capacitor
C5________22nF  63V Polyester or Ceramic Capacitor
C7________470µF  25V Electrolytic Capacitor
Q1_________BC547  45V 100mA NPN Transistor
IC1________TDA7052  Audio power amplifier IC
SW1_______ SPST  miniature Switch
MIC________Miniature electret microphone
SPKR_______8 Ohm Loudspeaker

Full-duplex Intercom PCB for your office and house

As both microphones and loudspeakers are always in operation, a special circuit is used to avoid that the loudspeaker output can be picked-up by the microphone enclosed in the same box, causing a very undesirable and loud “howl”, i.e. the well known “Larsen effect”.

A “Private” switch allows microphone muting, if required.

Full-duplex Intercom PCB for your office and house

The circuit uses the TDA7052 audio power amplifier IC, capable of delivering about 1 Watt of output power at a supply voltage comprised in the 6 – 12V range