CONSTRUCTION OF A SIMPLE SMOKE DETECTOR ALARM CIRCUIT

ABSTRACT A smoke detector alarm is a fire protection device that automatically detects smoke and also gives us warning. The individual smoke detectors are equipped with all the electronics required to both send and receive signals. They are battery operated and therefore they require no external connections. They can be installed by a homeowner just as they would a normal smoke detector. The proposed design is aiming to have Cost efficient system, Compact design, easily expandable, Simple to install, Replaceable components. The system was tested indoor and outdoor with different distance and with the presence of noise. Smoke Detectors are very useful in detecting smoke or fire in buildings, and so are the important safety parameters. In this project, a Simple Smoke Detector Circuit is constructed without using any Microcontroller. This circuit triggers the Buzzer whenever it detects Smoke near it. This circuit mainly uses MQ2Smoke/Gas sensor to detect the level of smoke. MQ2 gas sensor is also sensible to LPG, Alcohol, and Methane etc. In this circuit,a Buzzer was the Smoke alarm, which is driven by BC 337NPN transistor. Whenever smoke sensor senses smoke, it reduces its resistance and due to this decrease in resistance, voltage across the base of the transistor increases. Now when the voltage at the base terminal of transistor become more than or equal to 0.70v then transistor turns on and buzzer also starts beeping. And when there is no Smoke, both the indication components turns off as the voltage across base terminal of transistor goes below the 0.70v. Keywords:smoke detector alarm,MQ2 smoke sensor,LED,Buzzer,Transistor,power supply