There are Millions of fire alarm circuit available on the internet but the circuit shown below is probably the easiest for beginners to follow.
We are already aware of the importance of fire alarm and it’s presence in the crowded or public places.
So, presenting fire alarm as your project can be reasonable and it would be easy to explain it too. There is so much to say about its application.
The Speciality of my design is –
- Easy / simple circuit
- Low cost
- IR receiver
- LED ( red )
- Transistor BC548
- Resistor 100 Ohm 0.25W
- Small buzzer
- Connecting wires
- 4v – 6v power supply ( battery )
- Vero board / Breadboard
The pin configuration of BC 548 transistor is shown in the diagram below
fire alarm circuit
The circuit diagram for the fire alarm is shown below
Make your connections step by step as mentioned below
- Take BC548 transistor and connect IR Receiver to its base pin as shown in circuit diagram.
- Connect one terminal of buzzer to collector pin of transistor and the other terminal to positive source through switch.
- Make a series combination of red led and 10 Ohm resistor and connect it in parallel to buzzer.
- Add switch as shown in circuit.
- Connect the emitter pin of transistor to negative terminal of power source.
- Connect the power source and switch it on.
Working of fire alarm circuit
On this circuit the IR receiver is a sensor and when it is connected to base pin of transistor the combination ( sensor and transistor ) acts as switch.
Fire contains infrared rays. These infrared rays when fall on IR receiver it conducts a small current from positive terminal to base.
This small current to base allows the flow of current from collector to emitter. The flow of current through transistor completes the circuit of buzzer and led and makes them beep / glow.
The following precautions should be taken –
- Handle fire carefully. Make sure you make small fire using matchstick or lighter to demonstrate your project.
- Make connections according to the circuit diagram. Semiconductor devices like diodes and transistors are very sensitive.