MQ-135 Air Quality Sensor Module

The MQ-135 Gas Sensor module is one of the representatives of the MQ series gas sensors, which are used to determine the concentration of harmful substances in the environment. It can be used both in domestic conditions (determination of gas leakage) and in automation systems.

This sensor is able to detect such gases: ammonia, nitrogen oxides, alcohol vapors, smoke, gasoline and carbon dioxide.

The module is designed on the basis of the MQ-135 gas analyzer and the LM393 comparator, which converts information from the sensor into analog or digital signals. The semiconductor sensor gives a digital or analog signal to the logical output, which is proportional to the amount of harmful substances in the air.

The principle of operation of the sensor lies in the chemical reaction of the heated element of the MQ-135 sensor with harmful environmental gases. Therefore, the conductivity of the sensor's special coating depends on the gas concentration.

When using the sensor for the first time, it is necessary to leave it in working condition for several hours, this will ensure further quick connection of the working mode and more accurate readings.

There are 2 SMD LEDs on the sensor board. The PWR-Led indicates that voltage is applied to the board, and the OUT-Led indicates the operation of the comparator.

The module is connected from 4 pins. For a 5V power supply, the VCC and GND pins are used, and data transfer to the microcontroller is carried out through the D0 (digital signals) and A0 (analog signals) pins.

Module Specifications:

Supply voltage, V 2.5 ... 5
Current consumption, mA 180
Heater power, mW 900
Comparator LM393
Sensor type MQ-135
Response time, s ≤ 10
Recovery time, s ≤ 30
Operating temperature, °C -10 ... +50
Module dimensions, mm 32 x 20 x 27
Mounting holes, mm 2