Fire Alarm Using IR

Description

Description

Using IR Fire Alarm is an automatic fire alarm system designed to detect the unwanted presence of fire by monitoring changes in the environment associated with flaming. The IR Receiver sensor detects the fire and generates an analog voltage. This variation is monitored by forming a potential divider circuit.

In this Electric Fire Alarm Kit, analog variation is converted into digital form using a dual op-amp IC LM358. The op-amp is used as a comparator in non-inverting mode to do so. In this operation, we set a reference voltage with the preset (potentiometer). If the analog voltage from the sensor is greater than Vref, then the output is logically high on pin 7 else it is low. The analog input is connected to the pin5 of LM358. The output from the LM358 drives the ULN2803 IC (it act as a current amplifier to meet the current requirement to drive the relay).

This Fire Detector Kit is an inverted IC means when input is low output is high and vice versa. This IC drives the relay to activate the alarm which is a piece buzzer. The relay acts as an electromagnetic switch to switch the high voltage to activate the buzzer.

Block Diagram