ALLNET 4duino MQ-9 Carbon Monoxide and Flammable Gas Sensor (ALL_OY_3336)

The ALLNET 4duino MQ-9 sensor module is a high-quality semiconductor gas sensor designed for detecting carbon monoxide (CO) and flammable gases such as methane, propane, and LPG. It features both analog and digital outputs, making it ideal for integration with Arduino, Raspberry Pi, ESP32/ESP8266, and other microcontrollers. The onboard potentiometer allows easy adjustment of the digital output threshold, while the LM393 comparator ensures reliable signal processing. This sensor is perfect for air quality monitoring, gas leak detection, smart home systems, robotics, and DIY electronics projects.

Advantages

Dual output (analog and digital) provides flexibility for various applications. Adjustable sensitivity via potentiometer enables precise threshold setting. Fast response time (≤10 seconds) and recovery time (≤30 seconds) ensure real-time monitoring. Wide detection range for CO (10-1000 ppm) and flammable gases (100-10000 ppm). Compatible with popular microcontroller platforms. Low power consumption (approx. 150mA heater current).

Suitable for

• Air quality monitoring systems
• Gas leak detection in homes and industries
• Smart home automation
• Robotics and IoT projects
• DIY electronics and educational kits

Key specifications

• Sensor Type: Semiconductor Gas Sensor (MQ-9)
• Detected Gases: Carbon Monoxide (CO), Methane (CH4), Propane (C3H8), LPG
• Operating Voltage: 5V DC
• Output Type: Analog (0-5V) & Digital (TTL)
• CO Detection Range: 10 - 1000 ppm
• Flammable Gas Detection Range: 100 - 10000 ppm
• Heater Voltage: 5V DC
• Response Time: ≤ 10 seconds
• Recovery Time: ≤ 30 seconds
• Operating Temperature: -20°C to 50°C
• Operating Humidity: ≤ 95% RH (non-condensing)
• Interface: 4-pin header (VCC, GND, DOUT, AOUT)
• Adjustable Sensitivity: Yes (via onboard potentiometer)
• Comparator Chip: LM393
• Power Consumption: Approx. 150mA (heater current)
• Warm-up Time: ~20 seconds

Recommendations

For accurate readings, allow the sensor to warm up for at least 20 seconds before use. Use the analog output for precise gas concentration measurement and the digital output for threshold-based alarms. Avoid exposure to high concentrations of corrosive gases to prolong sensor life.