The MH-Z19C carbon dioxide gas sensor (hereinafter referred to as the sensor) is a general-purpose intelligent small sensor that uses the principle of non-dispersive infrared (NDIR) to detect the presence of C02 in the .Built-in temperature compensation: simultaneously has serial output, PWM output, easy to use. The sensor is a high-performance sensor made by closely combining mature infrared absorption gas detection technology with sophisticated optical circuit design and sophisticated circuit design.Detection gas: carbon dioxide supply voltage: DC (5.0 +/- 0.1) VAverage current: less than 40mA (@5V supply) current: 125 to (@5V supply)Interface level: 3. 3v (compatible with 5v)Measuring range: 400-5000PPMWarm-up time: 1minResponse time: T90less than 120sWorking temperature: -10-50degreeWorking humidity: 0-95%RH (no condensation)Pin description:Vin: +(in)GND: supply-(GND)PWM: PWMHd: HD (zero calibration, low level is effective for more than 7 seconds)Rx: UART (RXD) TTL level data inputTx: UART (TXD) TTL level data outputType: Gas SensorModel Number: MH-Z19Ccolour:GoldenMaterial:plasticsize:33 x 20mmPackage Contents:1 x MH-Z19C IR Infrared CO2 Sensor Module With cableOnly the above package content, other products are not included.Note: Light and different displays may cause the color of the item in the picture a little different from the real thing. The measurement allowed error is +/- 1-3cm.