It's important to have in our system a sensor that detects gas so we can apply it in our home in order to detect a gas leak. Now we´re going to describe how to connect to an Arduino board and read the concentration of gas.
In this section, we will use a gas sensor and Methane CH4. In this case, we will use an MQ-4 sensor that can detect concentrations from 200 to 10000 ppm.
This sensor has an analog resistance in its output and can connect to an ADC; it needs a coil energize of 5 volts. The image for the sensor can be seen as follows:
We can find information for the MQ-4 sensor at https://www.sparkfun.com/products/9404 ...