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by akoutmos 1295 days ago
When developing the book, I didn't have any additional meters or sensors to cross reference measurements with so I can't comment on the accuracy unfortunately. But I did notice that the changes in measurements made sense when the environment changed. I.e when I would exhale on the sensor, the measurement would rise and fall.

Another example was when I opened my window in my office. CO2 immediately dropped off (15:42 timestamp): https://twitter.com/akoutmos/status/1443233937015418891/phot...
2 comments
Havoc 1295 days ago
Yeah same - there is definitely a practical cause & effect practical correlation, but also a lot of effect without obvious cause in an environment that should be relatively stable. (one person, small apt, no co2 sources)

> additional meters or sensors

I've got a CCS811 as well but no luck yet. Acquired 2nd hand so unsure if broken from shipping or I'm being stupid with code or I broke it while soldering

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TeMPOraL 1295 days ago
This reminds me how my DIY build of Luftdaten kit (PM sensor) started reporting huge particulate spikes indoors, with no obvious cause. Took me ~2 days to figure out they're being caused by our ultrasonic humidifier, and another 2 days of looking through blogs and scientific papers to finally learn that one shouldn't be putting tap water into them (as they efficiently aerosolise the minerals and contaminants dissolved in it).
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buran77 1295 days ago
Both the SGP30 and the BME680 have a big weakness that I experienced some years ago when I trying putting an air quality sensor together. They correlated the TVOC readings with the temperature. And sometimes it was bad, like a difference of just 1 or 2 degrees Celsius could double or triple the TVOC readings at the lower end of the scale (~50ppb), and add maybe ~50% at the upper end (~500ppb).

Are you seeing the same behavior?

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