Simple Fire Alarm Circuit Using Thermistor – Electronic Circuit

• It is an electronic device used for detecting purposes that detect fire accidents like in malls, apartments, colleges, and many other places and activate a buzzer.
• The fire alarm is a simple circuit or very important electronic device for detecting fire at right time to avoid fire accidents.

Working

• The above shows the fire alarm circuit diagram where the component is used 10K thermistor, resistor, buzzer, transistor, variable resistor, capacitor, and diode.
• Here thermistor is used for monitoring the room temperature, when the room temperature increases, its resistance starts to decrease.

• As the resistance decreases then the output of the voltage divider will increases.
• The output of the voltage divider is connected to the transistor through a diode.
• The connected buzzer is ON only when the transistor is grounded and as the transistor increases the buzzer sound also increases.

Application

• The fire alarm circuit is used in the mall, apartments, industrial areas, and many more places which detect the fire through the circuit and prevent any disaster due to fire.
• It is used for security purposes in schools, offices, labs, etc.