Water overflow alarm Using NPN Transistor BC547

Circuit Description:

1. Water Sensor or Probes:
   • The water sensor or probes are placed in the area where water overflow needs to be detected. When water comes in contact with the sensor, it completes the circuit.
2. NPN Transistor (BC547):
   • The NPN transistor is used as a switch. When water completes the circuit, the biasing of the transistor changes.
3. Resistor (R1):
   • R1 is connected between the positive voltage rail and the base of the NPN transistor. It is used for biasing the transistor.
4. Buzzer:
   • The buzzer is connected to the collector of the NPN transistor. When water completes the circuit and biases the transistor, the buzzer is activated.

How It Works:

1. When water comes in contact with the water sensor or probes, it completes the circuit.
2. The completed circuit allows current to flow through the base of the NPN transistor, biasing it accordingly.
3. The biased NPN transistor turns on, allowing current to flow from the collector to the emitter.
4. The activated transistor powers the buzzer connected to its collector, producing an audible alarm.
5. The buzzer continues to sound as long as the water completes the circuit. When the water level drops, breaking the circuit, the transistor turns off, and the buzzer stops.