This project is a simple temperature-sensitive fire alarm system built using a 555 Timer IC, 7805 voltage regulator, thermistor, and basic electronic components.
It triggers a buzzer alarm when the temperature exceeds a set threshold, providing a low-cost fire safety solution.
- Course: 1EC101 – Electronics Devices & Circuits
- Semester: B.Tech. Semester III
- Institute: Nirma University, Ahmedabad
- Authors:
- Divyanshu Kalal (23BEC053)
- Dular Sarodia (23BEC056)
- 555 Timer IC (NE555) – 1
- NPN Transistor (BC547) – 1
- Thermistor (10kΩ) – 1
- Voltage Regulator IC (7805) – 1
- Resistors: 100kΩ, 4.7kΩ, 1kΩ
- Variable Resistor: 1MΩ
- Capacitor: 10µF
- Buzzer – 1
- Breadboard & 9V Battery
- Connecting Wires
- Thermistor detects a rise in temperature (resistance decreases).
- Transistor (BC547) switches ON when triggered by voltage change.
- 555 Timer IC operates in astable mode, generating a square wave.
- Buzzer produces a continuous sound as a fire alert.
- Variable Resistor (VR1) adjusts the sensitivity (temperature threshold).
- 7805 Voltage Regulator provides a stable +5V supply from a 9V battery.
The fire alarm circuit consists of a thermistor, transistor, 555 Timer IC, buzzer, and supporting components connected on a breadboard. The 7805 regulator ensures a stable +5V supply.
This project was physically assembled on a breadboard using the listed components.
The buzzer produces an audible alarm when heat is applied near the thermistor.
- Home & Office fire safety systems
- Industrial temperature monitoring (server rooms, storage areas)
- Educational demonstration for electronics learning
This project successfully demonstrates the use of simple electronic components to build a functional fire alarm circuit.
Key Learnings:
- Interfacing a thermistor, transistor, and 555 Timer IC
- Using a 7805 regulator for stable power supply
- Hands-on experience in breadboard assembly & troubleshooting