This circuit alerts us by ringing a siren sound instead of a buzzer when there is a fire accident at home. Here we use thermistor to sense the temperature. When it senses that the temperature of the environment is increasing above a given threshold, then it gives a signal. The temperature at which the circuit detects fire can be adjusted by using the potentiometer arrangement.
Get detailed information about this circuit by reading the post - Fire Alarm Circuit using Thermistor