Regents Biology 2015/2016

[ Smoke Sensor ]

Mohamed M.Elsaied

2017/2018

Supervised by :- Dr. Mohamed Ismail Badwey

Allied Medical Science

Medical equipment technology

Introduction

Mohamed M.Elsaied

2017/2018

Smoke Detectors are very useful in detecting smoke or fire(GAS) in buildings, and so are the important safety parameters.In this project, we are going to build a Simple Smoke Detector Circuit without using any Microcontroller.

This circuit triggers the Buzzer whenever it detects Smoke or fire near by it. This circuit mainly uses MQ6-MQ2 Smoke/Gas sensor to detect the level of smoke.

MQ6 –MQ2 gas sensor is also sensible to LPG, Alcohol, and Methane etc.Here we have used Buzzer as a Smoke alarm, which is driven by BC547 NPN transistor.

Circuit Diagram

Mohamed M.Elsaied

2017/2018

Components Required

Mohamed M.Elsaied

2017/2018

BC547 Smoke Sensor (MQ2/MQ6) 1K 10k POT Power Supply LED Buzzer Connecting wire Jumper wire

Mohamed M.Elsaied

2017/2018

Smoke Sensor (MQ2/MQ6)

Mohamed M.Elsaied

2017/2018

Smoke Sensor (MQ2/MQ6)

Smoke circuit in Bread Board

Mohamed M.Elsaied

2017/2018

General Explanation:

Mohamed M.Elsaied

2017/2018

Working of this Smoke Detector Alarm Circuit is easy. In this project, we have used transistor operating properties to work this circuit as a smoke detector. As we already know that we have used a BC547 NPN transistor which will turn on whenever it gets least 0.70v at its base terminal. So we have applied a Voltage Divider Circuit at its base .

Mohamed M.Elsaied

2017/2018

But before using this circuit, we need to calibrate it by using pot. In calibration, we have applied voltage just below than 0.70v at transistor base.

Whenever smoke sensor senses smoke, it reduces its resistance and due to this decrease in resistance, voltage across the base of the transistor increases.

Working Explanation:

Mohamed M.Elsaied

2017/2018

Now when the voltage at the base terminal of transistor become more than or equal to 0.70v then transistor turns on and LED lights up 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.

Mohamed M.Elsaied

2017/2018

PCB Layout

Mohamed M.Elsaied

2017/2018

Video to explain that