ALLNET 4duino MQ-135 Air Quality Sensor (ALL_OY_3337)

The ALLNET 4duino MQ-135 Air Quality Sensor is a versatile gas sensor module designed for detecting a wide range of gases including ammonia (NH3), nitrogen oxides (NOx), alcohol, benzene, smoke, and carbon dioxide (CO2). Based on the semiconductor MQ-135 sensor chip, it provides both analog and digital output signals, making it compatible with Arduino, Raspberry Pi, ESP32, and other microcontrollers. The module features an onboard potentiometer for sensitivity adjustment and indicator LEDs for power and digital output status.

Advantages

This sensor offers reliable detection of multiple harmful gases, enabling air quality monitoring in various environments. Its dual output interface (analog and digital) allows flexible integration into projects. The adjustable sensitivity ensures optimal performance for different applications, while the compact design and low power consumption make it suitable for portable and stationary setups.

Suitable for

• Air quality monitoring systems
• Indoor air pollution detection
• Gas leakage alarms
• Environmental sensing projects
• Educational and hobbyist electronics

Key specifications

• Sensor Chip: MQ-135
• Detected Gases: NH3, NOx, Alcohol, Benzene, Smoke, CO2
• Operating Voltage: 5V DC
• Output Type: Analog (0-5V) & Digital (TTL)
• Detection Range (NH3): 10-1000 ppm
• Detection Range (Alcohol): 10-300 ppm
• Detection Range (Smoke): 10-300 ppm
• Detection Range (CO2): 10-10000 ppm
• Response Time: ≤ 10s
• Recovery Time: ≤ 30s
• Heating Voltage: 5V DC
• Heating Power: ≤ 750mW
• Operating Temperature: -10°C to 50°C
• Operating Humidity: 95% RH (non-condensing)
• Interface: 4-pin header (VCC, GND, DOUT, AOUT)
• Adjustable Sensitivity: Yes, via onboard potentiometer
• Indicator LEDs: Power LED, Digital Output LED
• Compatibility: Arduino, Raspberry Pi, ESP32, Microcontrollers

Recommendations

For accurate readings, allow the sensor to preheat for at least 24 hours before first use. Calibration in clean air is recommended to set the baseline. Use the analog output for precise concentration measurements and the digital output for threshold-based alarms.