Customer:
I’m reading the analog output from the MQ-8 gas sensor breakout board on my microcontroller. The readings come in around 2500-2800, which is outside the advertised 100-1000 ppm range. I’m not sure whether these values correlate to a resistance, voltage, current, or a ratio like Rs/Ro.
Originally submitted via email support on 30 July 2025. Migrated to the forum for community visibility.
Soldered Support:
The correct detection range of the sensor is 100–10,000 ppm, as specified in the official datasheet. The sensor outputs an analog voltage which corresponds to the gas concentration. This voltage is used to calculate the sensor’s resistance (Rs), as outlined in the gas sensor technology documentation.
To determine the gas concentration, this resistance value is then compared to a baseline resistance (R0), which is obtained during calibration. If you are seeing irregular readings, it’s likely due to insufficient preheating. MQ sensors require a preheating period of at least 24 hours in clean air (preferably in an environment free of the target gas, such as a vacuum) while powered at 5V. This step is crucial for sensor stabilization and accurate measurements.
Review the Arduino Library Examples and Sensor Operation Documentation for more guidance.