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MQ Series Gas Sensor ModuleThis MQ-9 sensor module is a simple to use carbon monoxide (CO) and combustible gas (Methane (CH4), LPG) sensor, suitable for detecting CO, methane and LPG gas concentrations in the air. The MQ-9 can detect CO gas concentrations anywhere from 10 to 1000ppm and combustible gasses from 100-10000ppm. Suitable for home and industrial use, it has fast response and recovery characteristics, long life and reliable stability.

The module features dual signal outputs: An analog output (0V to ~5V), the higher the gas concentration, the higher the voltage, and a digital TTL level output to signal the presence or absence of gas. The TTL threshold is adjustable with the onboard potentiometer.


  • Operating voltage: 5 Volts DC (VCC Pin) 
  • Maximum power consumption: 800mW (160mA at 5V)
  • Dual signal output (analog (AO pin) and TTL (DO pin) level output)
    • TTL output signal is normally low, goes high when has is detected. Threshold is adjusted with the onboard potentiometer
    • 0 ~ 5V analog output voltage, the higher the concentration, the higher the voltage
  • Indicator LEDs
    • Power
    • DO (Digital Output On)
  • Detectable CO concentrations: 10-1000ppm
  • Detectable Combustible Gas (CH4, LPG) concentration: 100-10000ppm
  • Dimensions (approximate): 32mm x 20mm x 27mm LxWxH (1.25 x 0.8 x 1.1 inches)
  • Weight: 7 grams
MQ-9 Gas Sensor Module Schematic

Usage Tips:

  • Allow the module to preheat for a few minutes to ensure accurate gas detection. Calibrate and test the module in the specific gas environment of your application to establish baseline readings and thresholds for gas concentration alerts.
  • When the sensor is powered, it needs to be warmed up about 20 seconds so the measured data becomes stable.
  • Caution: Use of this gas sensor module in environments with gas leaks or in the presence of carbon monoxide may pose safety risks. Follow safety guidelines and standards for gas detection and ventilation in such environments.

Other Resources and Links:
How to Calibrate & Use MQ9 Gas Sensor W/ Arduino on Instructables.

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