Project Description:

The Thermistor-based simple fire alarm uses an IC 555 and a thermistor to detect heat and trigger an alarm in case of a fire. The project uses a thermistor, which is a type of resistor whose resistance changes with temperature, to sense the temperature in the environment. When the temperature rises beyond a certain threshold, the thermistor's resistance changes, which triggers the IC 555 to sound an alarm.

Working Method:

The thermistor is connected in a voltage divider circuit with a fixed resistor, which provides a reference voltage to the IC 555. The output of the voltage divider is connected to the trigger pin of the IC 555. When the temperature rises and the resistance of the thermistor decreases, the voltage at the trigger pin falls below a certain threshold, which triggers the IC 555 to output a high signal. This signal is then used to activate an alarm circuit, which sounds an alarm to alert occupants of the presence of a fire.

To set up the project, you will need to connect the thermistor and the fixed resistor to the voltage divider circuit and the output of the voltage divider to the trigger pin of the IC 555. The output of the IC 555 can be connected to an alarm circuit or a buzzer to sound an alarm in case of a fire.

Overall, this project provides a simple and cost-effective way to detect fires using a thermistor and an IC 555, and can be used to provide basic fire detection in small rooms or homes.