Air Quality Sensor MQ135 (Analog/Digital) The Air Quality Sensor MQ135 (Analog/Digital) is a high-precision gas detection module designed to measure air pollution levels with exceptional sensitivity and stability. This advanced sensor is widely used in indoor air-quality monitoring systems, smart-home applications, IoT solutions, and industrial safety tools. Its ability to detect harmful gases such as ammonia (NH3), nitrogen oxides (NOx), benzene, smoke, alcohol, and carbon dioxide makes it an essential component for engineers, students, and makers working on environmental and safety-related projects. This module supports both analog and digital outputs, offering great flexibility for integration with microcontrollers such as Arduino, ESP32, ESP8266, Raspberry Pi, STM32, and other development platforms. With its compact design and fast response time, the Air Quality Sensor MQ135 (Analog/Digital) provides accurate readings and stable long-term performance, making it suitable for both educational and professional applications. Key Features High-sensitivity gas detection module. Supports analog and digital outputs for flexible interfacing. Detects multiple gases: NH3, NOx, benzene, CO2, alcohol, and smoke. Adjustable digital threshold using the onboard potentiometer. Fast response and high stability over long-term operation. Long lifespan and low power consumption. Ideal for smart-home systems, air-quality analyzers, and safety devices. Easy to interface with microcontrollers such as Arduino and ESP boards. Applications The Air Quality Sensor MQ135 (Analog/Digital) is used in many environmental and industrial fields, including: Indoor air-quality monitoring Smart ventilation systems CO2 and toxic gas detectors Environmental IoT projects Safety and alarm systems Industrial emission monitoring School and university engineering labs DIY electronics and prototyping Its wide gas-detection range makes it one of the most versatile and reliable modules for monitoring air pollution in real time. Datasheet (Technical Specifications) Model: MQ135 Operating Voltage: 5V DC Output Type: Analog Digital Gas Detection Range: Ammonia (NH3) Nitrogen oxides (NOx) Benzene CO2 Alcohol vapors Smoke Load Resistance: 20 kΩ Heater Resistance: 31 Ω ± 3 Ω Heater Voltage: 5V ± 0.2V Heater Power Consumption: ≤ 150mW Preheat Time: 20 seconds Response Time: < 10 seconds Operating Temperature: −10°C to 50°C Board Includes: MQ135 sensor Comparator IC (LM393) Adjustable potentiometer Power and status LEDs Dimensions: Standard compact module size suitable for most IoT enclosures. Why This Sensor Is Unique The Air Quality Sensor MQ135 (Analog/Digital) offers a rare combination of multi-gas detection, plug-and-play compatibility, and dual-output flexibility. Its powerful sensitivity and low noise levels allow accurate gas measurement even in fluctuating environments. With onboard digital calibration and strong analog performance, it is widely trusted in academic projects, environmental studies, and real-world industrial applications.
