What is an MQ-2 Smoke Sensor?

The MQ-2 smoke sensor is sensitive to smoke and to the following flammable gases: - LPG - Butane - Propane - Methane - Alcohol - Hydrogen The resistance of the sensor is different depending on the type of the gas. The smoke sensor has a built-in potentiometer that allows you to adjust the sensor sensitivity according to how accurate you want to detect gas.

How does it Work?

The voltage that the sensor outputs changes accordingly to the smoke/gas level that exists in the atmosphere. The sensor outputs a voltage that is proportional to the concentration of smoke/gas.

Pin Wiring

The MQ-2 sensor has 4 pins. Pin-------------------------------------Wiring to Arduino Uno A0-------------------------------------Analog pins D0-------------------------------------Digital pins GND-----------------------------------GND VCC------------------------------------5V