Senitive material of MQ136 gas sensor is SnO2, which with lower conductivity in clean air. When the target Hydrogen sulfide gas exist, the sensor’s conductivity is higher along with the Hydrogen sulfide concentration rising. Please use simple electric circuit, Convert change of conductivity to correspond output signal of gas concentration. MQ136 gas sensor has high sensitity to Hydrogen sulfide, Low sensitivity for other combustible gas. It is with low cost and suitable for different application.