Overview Sensitive for benzene, alcohol, smoke Output voltage boosts along with the concentration of the measured gases increases Fast response and recovery Adjustable sensitivity Signal output indicator Specifications Power: 2.5V ~ 5.0V Dimension: 40.0mm * 21.0mm Mounting holes size: 2.0mm ApplicationsAir quality monitorHow to UseIn the case of working with a MCU: VCC ↔ 2.5V ~ 5.0V GND ↔ power supply ground AOUT ↔ MCU.IO (analog output) DOUT ↔ MCU.IO (digital output) Photos DownloadsDevelopment resources: demo codes, schematic, datasheets, etc.Wiki: www.waveshare.com/wiki/MQ-135_Gas_SensorSelection Guide Part Number Sensitive Gas Application MQ-135 Gas Sensor benzene, alcohol, smoke Air quality monitor MQ-2 Gas Sensor LPG, propane, hydrogen Gas leakage detector MQ-3 Gas Sensor alcohol, ethanol Car alcohol alarm, breathalyser MQ-5 Gas Sensor LPG, natural gas, coal gas Gas leakage detector MQ-7 Gas Sensor carbon monoxide Carbon monoxide monitor Package Content: Weight: 0.011 kg MQ-135 Gas Sensor × 1 4-pin custom connector jumper wire × 1