MQ-135 Air Quality Gas Sensor Module

The MQ-135 Gas Sensor Module is used to detect harmful gases and monitor air quality in the environment. It is sensitive to gases such as ammonia (NH₃), nitrogen oxides (NOx), alcohol, benzene, smoke, and carbon dioxide (CO₂). This module provides analog and digital outputs, making it easy to interface with development boards like Arduino, ESP8266, and ESP32. It features an onboard comparator and adjustable potentiometer to set the gas detection sensitivity. The MQ-135 sensor is widely used in air quality monitoring systems, smart home devices, environmental monitoring projects, and educational electronics applications. Key Features Detects multiple harmful gases Suitable for air quality monitoring Adjustable detection sensitivity Analog and digital output signals Onboard LED indicators Easy interface with microcontrollers Technical Specifications Parameter Value Sensor Type MQ-135 Gas Sensor Operating Voltage 5V Detectable Gases NH₃, NOx, Alcohol, Benzene, Smoke, CO₂ Output Type Analog and Digital Comparator LM393 Preheat Time ~20 seconds Interface Pins VCC, GND, DO, AO Pin Configuration Pin Description VCC Power Supply (5V) GND Ground DO Digital Output AO Analog Output What’s in the Box 1 × MQ-135 Air Quality Sensor Module Ideal For Air quality monitoring systems Environmental monitoring projects Smart home automation Arduino and IoT projects Educational electronics experiments