Anyone with a MH-Z14?

My MH-Z14 CO2 sensor seems unreliable.

Does anyone have any experience with these things?

The PWM output is easy to convert to ppm, but the dutycycle stays the same, more or less.

Am I the first person to be ripped off by the chinese selling me cheap junk?

The datasheet seems straight forward. You can get your data via softserial into any Arduino. Notice the warmup and response times are rather sluggish. Also, if you're standing there looking at it then it's being flooded irregularly by your own CO2.

Yes the datasheet is almost too straight forward, which reasures me that Im not the one messing up. The warmup time is not a problem, I have had the sensor looking at me on my table for some time, hooked up to both the serial monitor and an oscilloscope, the PWM doesnt change when I expose the sensor to CO2. My hope must then be that the PWM out is broken, and serial is the way forward.

That was just the first datasheet I found, and a little anemic. There may be others with more detail.

I fount the blog where everything is posted very well about MH-Z14 and Arduino and python code. hear you also get code for UART as well as PWM.