The output voltage of MQ-6 gas sensor varies depending on the concentration of the gas in the air. In general, the output voltage decreases as the concentration of the target gas increases. The sensor’s output voltage can be read using an analogue-to-digital converter (ADC) and then processed by a microcontroller to determine the concentration of the target gas.
The sensor output voltage also varies depending on the temperature and humidity of the environment. So, it is important to calibrate the sensor in the specific environment where it will be used. Also, the sensor should be heated for a few minutes before using it to get an accurate reading. An image of the MQ-6 is shown in Fig. 1.
MQ-6 module has four pins: VCC, GND, AO, and DO. VCC is the positive power supply pin, typically connected to a voltage between 2.5V and 5V. GND is the ground pin, connected to the negative power supply. AO (analogue output) pin gives the sensor’s output voltage, which can be read using an ADC. DO (digital output) pin can be used to get a digital output from the sensor.