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Simple Fire Alarm Circuit | Fire Detector System | Basic Electronics project

There are several useful applications and projects starts with the basics of electronics.The basic electronics projects that are easy to make and have so many effective applications.Here is the project about fire detection alarm system basic circuit.This is the bread board based electronics project using the temperature measuring thermistor.A thermistor based project for fire detection.This is the basic circuit project we will see how we can make sensor module based fire alarm circuit in the coming posts.a thermistir based fire detector system circuit is easy to make and cheapest in price.This is the biggners level electronics project.This project is also good for home based fire security and the similar fire detecting applications.


  1. Objective
  2. Required Components
  3. Pinout Configurations
  4. Circuit diagram
  5. Working of Fire detecting alarm project
  6. Results

01Objective of fire Alarm Project

To detect the fire and turning on the alarm.The output of the project is the buzzer when ever the thermistor detects heat and temperature of fire the buzzer will turn on.

02Required Components


Components List

1 Resistors (1kΩ)


2 Potentiometer-(POT) (10KΩ)


3 6-Volt DC Power Supply / Battery


4 Capacitor (10µF / 16-Volt)


5 Diode (1N4001)


6 6-Volt Buzzer


7 Thermistor High resistance  (NTC)


8 Transistor ( BC548 )



fire alarm project

03Pinout Configurations

There is Transistor BC548 Connected with buzzer and Resistor.Transistor BC548 needs a pin-out configuration.A simplest and common transistor.The center leg of the transistor is the base and the last one is the emmitter. The potentiometer has 3 legs the very first is the input voltage ,the center is the output an the last is the ground(GND).See the following fig. for pinout configurations.


fire circuit pinout

04Circuit Diagram of Fire Detector


fire alarm circuit diagram

05Working of the Project

  • The Transistor is used for switching purpose.
  • To drive the transistor the potentiometer and thermistor creates a potential divider network.
  • Thermistor is a kind of Resistor that used to measure Temperature.Whenever the temperature increased the thermistor decreases its resistance.
  • When a voltage drop measure at potentiometer the transistor will turn on.
  • By varying the POT-Potentiometer we can set the threshold value for temperature measurement.


The Buzzer will be turned on when ever a fire or heat in front of thermistor. To test the circuit light up a candle in front of thermistor and Adjust the POT Value to measure the output results.

You can also download this project in pdf file.

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