ADIY Gas Sensor module MQ7 provides an analog output corresponding to the concentration of the gases in the air and an easy-to-use digital output. The onboard potentiometer can be used to set the maximum gas concentration beyond which the digital output gets triggered.

Just power the module with 5V set the threshold and you can start getting the gas concentration of the air around the sensor! An onboard LED signals the presence of any gas.

The digital output can be easily interfaced to microcontrollers and other circuits. The analog output can be hooked up to an ADC of a microcontroller to get a wide range of sensor reading.