MQ-135 Air Quality Sensor Module

MQ-135 Air Quality Sensor Module is designed to detect a wide range of gases such as ammonia, nitrogen oxide, alcohol, benzene, smoke, and carbon dioxide. It is ideal for indoor air quality monitoring systems, offering fast response time, wide detection range, and stable output for embedded projects like Arduino, ESP8266, and STM32-based IoT devices.

Key Features:

• High sensitivity to multiple gases including NH3, NOx, alcohol, benzene, smoke, and CO2
• Analog and digital output for easy integration with microcontrollers
• Fast response time and recovery
• Low cost and long life
• Adjustable sensitivity via onboard potentiometer

Technical Specifications:

• Operating Voltage: 5V DC
• Load Resistance: 10kΩ (adjustable)
• Heater Consumption: ≤ 800 mW
• Output: Analog (AO) and Digital (DO)
• Preheat Time: 20 seconds
• Sensing Range: 10–1000 ppm (varies by gas)

Mechanical Specifications:

• Sensor Type: MQ-135 Gas Sensor
• PCB Material: FR4
• Mounting Holes: 4 holes for screw mounting
• Indicator LEDs: Power and digital output status

Dimensions:

• Length: Approx. 32mm
• Width: Approx. 20mm
• Height: Approx. 22mm (with sensor)
• Mounting Hole Diameter: 3mm

Mounting Options:

• Direct mounting on chassis or case using screw holes
• Can be mounted on a breadboard or sensor base board

Schematic Diagram, Connection, Wiring and Pinout:

• VCC: Connect to 5V DC power supply
• GND: Connect to system ground
• AO: Analog output to microcontroller ADC
• DO: Digital output (triggered when threshold is reached)

Datasheet/User Manual:

• MQ-135 Sensor Datasheet (PDF)
• MQ-135 Module User Manual

Applications:

• Indoor air quality monitoring
• Smart home and HVAC systems
• Air purification and ventilation control
• IoT and environmental sensor networks
• School and laboratory gas leak demonstration

Equivalent:

• MQ-2: For smoke, LPG, methane, propane
• MQ-3: For alcohol and ethanol detection
• MQ-9: For CO and methane detection

Package Includes:

• 1 x MQ-135 Air Quality Sensor Module