Concepts related RC coupled amplifiers.
Application of transistor in amplifier circuits.
The Low Cost Transistorised Intercom allows the voice at one end to be amplified and listened to at the other end through a loudspeaker as a one-way intercom. A two-way intercom can be similarly assembled using two such kits.
No. of ICs used: None
The circuit of the Low Cost Transistorised Intercom comprises of a 3-stage resistor-capacitor coupled amplifier. When the ring button (S2) is pressed, the amplifier circuit formed around two BC548 NPN transistors (denoted as T1 and T2) gets converted into an asymmetrical astable multivibrator generating ring signals. These ring signals are amplified by a third NPN transistor BEL187 (T3) to drive the loudspeaker of the earpiece. Current consumption of this intercom is only 10-15mA.
For making a two-way intercom, two identical units can be used. Output of one amplifier unit would go into the speaker of the other unit and vice versa.
Brand: Kits'n'spares, Marketed by: Kits'n'spares
Click To View Circuit Diagram