Fire alarm

Simple Fire Alarm Circuit with full explanation

1. WELCOME Sri Venkatesa Perumal College of Engineering & Technology Department of E C E Project by Gowtham Sana 14G05A0401

2. FIRE ALARM Introduction Circuit Diagram Operation Components

3. A simple potential divider arrangement using thermistor is capable of  sensing the temperature (presence of fire ) and alerting us with a warning signal. This is suitable for your  home security systems .

4. Components required Power supply Potentiometer (10KΩ) Capacitor (10 µ F, 16V) BC548 transistor High resistance thermistor (NTC) Diode (1N4001) 6V Buzzer Resistors (1kΩ)

5. Circuit Diagram

6. Operation Consider the temperature of the atmosphere is around 25°C, and then the resistance of thermistor is high so the voltage across the thermistor is also high according to the basic ohm’s law V=IR.

7. As temperature rises, the resistance of thermistor decreases so that the drop across the resistor R1 increases which turns ON the transistor.

8. Applications Home Security System School/College Labs Industries R&D Cells

9. Advantages Sensing of fire(Heat) easily Simple Circuit Low Power Consumption Low cost

10. Dis Advantages No longer use Senses near by the Fire(Heat)only Uses continuous Power Supply

11. Future Scope To overcome disadvantages and looking for implementation of Automatic Fire detection. In the place of Thermistor have to use Sensors… Uses the Speakers instead of Thermistor with Warning message & Audio alert signal.

12. Practical Circuit