AITRIP 1PCS MH-Z19B Infrared Carbon Dioxide Monitor Sensor CO2 Detection Sensor Module UART PMW Wave Output 0-5000ppm+Cable

On arrival, I hooked the sensor up to 5 volts, and sent the output to my rather ancient scope. Movie attached. Scope is set on 0.1 seconds per division on the time axis, and is triggering on the PWM pulse rising edge. Pulse width is thus about 200 milliseconds on room air, and if I blow on the sensor, the pulse width becomes longer. Y-axis voltage is 2v per division, so the pulse height is about 3 volts. A nice Tek digital storage scope would be nice about now, but I'm fresh out.Plan is to hook the sensor to an Arduino, measure the pulse width, and convert the time to ppm CO2.

Unsure what to do with this thing. On a fresh boot it seems happy and sends sane-looking values, but eventually it'll just freak out and start sending 5000ppm/122F constantly. Rebooting it fixes it but resets calibration which makes it useless.

Update: The new sensor works great. Just had some bad luck I guess.Sensor did not show any activity on uart or pwm. Vo seemed to occasionally alternate between 0.54V and 0V. Luckily Amazon is nice when this happens. I will get another one and then update my review. Btw it was indeed a genuine sensor, though there was some light corrosion on the bottom of the board.

I built this into an air quality monitor. The ad says 5k ppm range but mine goes to 10k. (im happy about this)The temperature reading of this thing is not very good for measurement, but it compensates the co2 reading and serves that function well.I used to have an MG811 and this is far superior at half the cost and 1/10th the power requirements. I ran this with an ESP32, oled screen and bmp280 powered by a single 18650 for 20 hrs. Would buy again.

Appears to be a genuine MH-Z19B. Using the UART interface, I get readings that appear accurate.The unit does require a few minutes to preheat, and during that time it will report a reading of zero.