Description:MQ-2 gas sensor sensitive material used in clean air conductivity is lower tin dioxide (SnO2). When the sensor is present in the environment in which the combustible gas, the sensor's conductivity increases with the concentration of combustible gases in air increases. Using a simple circuit can be converted to the change in conductivity of the gas concentration with the corresponding output signal. MQ-2 gas sensor for gas, propane, hydrogen of high sensitivity, natural gas and other combustible vapors detection is also very satisfactory. The sensor can detect a variety of flammable gas, is a low-cost sensors for a variety of applications.