Working of Gas sensors

The MQ-2 sensor Module Detect the percentage of the Smoke or concentration of the Gases around the Sensor. In clean air the oxygen is absorbed on the surface of the sensing material so the Output voltage is Low, In the case of Fire or Leakage of LPG gas, the smoke of the Fire or the concentration of LPG gas touch athe Sensing material then the sensing plate start heating it reduce the resistivity and flow maximum amount of voltage at its output pin.

Pin No:

Pin Name:

Description

For Module

1

Vcc

This pin powers the module, typically the operating voltage is +5V

2

Ground

Used to connect the module to system ground

3

Digital Out

You can also use this sensor to get digital output from this pin, by setting a threshold value using the potentiometer

4

Analog Out

This pin outputs 0-5V analog voltage based on the intensity of the gas

For Sensor

1

H -Pins

Out of the two H pins, one pin is connected to supply and the other to the ground

2

A-Pins

The A pins and B pins are interchangeable. These pins will be tied to the Supply voltage.

3

B-Pins

The A pins and B pins are interchangeable.   One pin will act as output while the other will be pulled to ground.