We made a fire alarm using thermistor, 555 timer and many other component. Video Link: https://youtu.be/vHahr1J_Cgk

1. FIRE ALARM USING THERMISTOR &
555 TIMER

2. INSTRUCTOR: RETHWAN FAIZ
Name ID
1. Shihab, Mehedi Hasan 14-27923-3
2. Hasan, MD Asif 14-27793-3
3. Farheen, Shuchi 14-27893-3
4. Emon, Mishbaul Haque 15-30075-2
5. Shaun, MD Saruar Abedin 14-27958-3
Group Members:

3. Introduction:
 Detects fire in ambiance at very early stage by sensing fire or
heat.
 Warns people about the fire to take preventive steps.
 Life saver.
 Especially used in Banks, data centers, gas station also in
educational Institutes etc.

4. Quick View :

5. Components:
 555 Timer IC
 NPN Transistor BC547
 Thermistor (10K)
 Resistors (1k,100k,4.7K)
 Variable Resistor
 Capacitor
 Buzzer and Battery (9V)

6. Circuit Diagram

7. Simulation (More than 70)

8. Simulation (Below 50)

9. Working Concept
 The 555 timer IC has been configured in Astable mode to
oscillate sound.
 Capacitor charges and discharges through resistance.
 Capacitor charges till 2/3 vcc and discharges till 1/3vcc.
 During the charging time OUT PIN 3 of 555 IC remains high.
 On discharging time it remains low.
 Buzzer is connected to OUT pin.
 Oscillation frequency can be controled.

10. Advantages & Disadvantages
Advantages:
 Alert people of a potential fire.
 Really important to ensure the safety of everyone in the premises.
 Can take necessary steps against fire.
 Prevent losses.
Disadvantages:
 False alarms caused by cooking.
 False alarms will lead to some people not responding to the alarm with the alacrity.

11. Conclusion
 It gives sound from fire alarm when fire attacks to industries,
warehouses, apartments etc.
 It is most efficient, simple and less complex circuit.
 Designed with less equipment.
 It can be used to provide security at warehouses where
storage and protection of various types of goods is main
concern
 Works for home security too.