3 Review(s)

The circuit is basically an audio oscillator. The fencing alarm circuit described below doesn’t give any sounds when the wire loop is connected, i.e. the base of T-1 is shorted to its emitter. Hence the base current cannot flow. And when the loop is broken the current startflowing through T-1 and circuit starts oscillator sounding an alarm. COMPONENTS USED T-1 Silicon Transistor (NPN) T-2 Silicon Transistor (PNP) R-1 330 Kilo Ohms Carbon Resistor (Fixed) R-2 10 Kilo Ohms Carbon Resistor (Fixed) C-1 0.02 µf Ceramic disc Capacitor. Battery 9V d.c. Speaker 8 Ohm