The MQ gas sensor modules

The MQ gas sensor

The MQ series of gas sensors currently consists of 17 different sensors to measure the concentration of different gases. These components contain a small heating element with a gas sensor that is sensitive to a certain gas. The sensors provide an analog signal of the gas concentration and are fairly easy to connect.

When this sensor does not detect gas, the output voltage will be low. As the gas concentration increases, the output voltage of this sensor will increase.

The heating element

The heating element and the voltage on it is very important. Some MQ sensors have a heating element that works on 2V, others on 5V and with some sensors this must be increased in steps. This can best be solved via a microcontroller with a PWM signal (for example with a transistor since the heating element requires a lot of current).

The sensors with an element that requires 5V or 6V can easily heat up to 50 to 60 degrees Celsius. Furthermore, the element must pre-heat for about 3 minutes before the output becomes stable enough to read.

Burn in

Some MQ sensors also require a 'burn-in', also called 'preheat'. This means that the heating element must burn in for 12 to 24 hours. When purchasing these modules, they should first be connected to the required voltage for 12 to 24 hours in order to give more reliable results.

Always consult the datasheet for this information!

The MQ gas sensor module

Fortunately, this MQ sensor series also has an MQ sensor module series. These modules have the necessary electronics to control the sensor with the addition of a potentiometer for a digital trigger signal.

+5V -----> 5V
DOUT -----> 0V or 5V (sensitivity adjustable with potentiometer)
AOUT -----> Analog output
GND -----> GROUND

Reading the MQ sensor with the Arduino

Reading the sensor with Arduino requires little code, with analogRead the current value can be read.