Sensor of smoke

1. Regents Biology 2015/2016
[ Smoke Sensor ]
Mohamed M.Elsaied
2017/2018
Supervised by :- Dr. Mohamed Ismail Badwey
Allied Medical Science
Medical equipment technology

2.  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.

3.  Circuit Diagram
Mohamed M.Elsaied
2017/2018

4.  Components Required
Mohamed M.Elsaied
2017/2018
 BC547
 Smoke Sensor (MQ2/MQ6)
 1K
 10k POT
 Power Supply
 LED
 Buzzer
 Connecting wire
 Jumper wire

5. Mohamed M.Elsaied
2017/2018
 Smoke Sensor (MQ2/MQ6)

6. Mohamed M.Elsaied
2017/2018
 Smoke Sensor (MQ2/MQ6)

7.  Smoke circuit in Bread Board
Mohamed M.Elsaied
2017/2018

8.  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 .

9. 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:

10. 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.

11. Mohamed M.Elsaied
2017/2018
PCB Layout

12. Mohamed M.Elsaied
2017/2018
 Video to explain that