81–90 of 218 posts
Reminds me of dash cams which almost all use the same image sensor even if they advertise different levels of image quality.
I bought a fairly expensive air quality monitor. Accuracy wasn’t what caused me to go with a more expensive model. I wanted CO2 readings, which most models under $200 don’t provide.
can you share which one was it? I'm also looking for one, and CO2 is surprisingly uncommon. I'd also love for it to be HomeKit compatible, which makes it nearly impossible
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Aranet4 is the way to go. Tried going cheap and getting a bunch of Vitalights later as additional monitors but ended up finding out that their results were all over the place. Returned the Vitalight. Kept the Aranet4. I do have plans to build a few Airgradients when I have time.
co2.click also worth a look: https://www.co2.click/
As a bonus, the collected data by the sensors.community project is public, and here is the walkthrough of data analysis with ClickHouse: https://clickhouse.com/docs/en/getting-started/example-datas...
This is not a joke, I am really asking: how do you measure the accuracy of an air quality monitor? Comparing it to another monitor? Creating an air pollution condition and seeing how close to that is the measurement?
The state of the art for reasonably priced CO2 monitors seems to be that they hard code in the "ambient" Co2 level and instructions tell you to let it sit outside every once in a while. The the sensor adjusts can adjust it's baseline accordingly , assuming that the lowest CO2 level it's seen in the last week or so is equivalent to the "ambient" outside level. Ofc this is susceptible to issues and can require even mor…
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The above linked GitHub issue has been closed for over 6 months, and aside from that was posted to the wrong project rather than to an official AirGradient channel.
This has been analysed extensively on our forum and the root cause was a bug in the software serial Arduino library as well as a slightly wrong command send from our library. Details [1] [1] https://forum.airgradient.com/t/co2-reading-of-3-constantly/...
I specifically remember softserial was very problematic, and actually reading the code convinced me to dump it. Might be fixed now, but there's timing code in there that could easily break on a compiler update because it's still written in C++ and has handcounted delays based on counting instructions in compiler output. Now, maybe they recheck those on every single release of avr-gcc to make sure the count didn't change, but why rely on that? We're talking about the same maintainers here who kept conditionally compiled ASM code to manually push and pop the stack in every function because some absolutely ancient MacOS 9(or something like that) version of GCC somehow didn't emit those instructions. That was still there in 2015, hopefully they removed it since then...
It also sets interrupts. I don't like library code doing this at all. I wanted complete control over that so I always know what interrupts might occur. And even worse it uses a circular buffer for storing data but IIRC offers no method of detecting a full buffer. Which led to a lot of "fun" debugging.
Arduino libraries are fine for simple prototyping, but they're not high quality enough for writing reliable microcontroller code.
Cheap sensors aren't as good as expensive ones.
This is like saying a DHT11 has the same accuracy as a SHT31.
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Because like anything analog these days, they are hard to find?
I can find mechanical scales very easily in the Netherlands, but they're more expensive. On Alibaba I see that digital bathroom scales are about $2.50 and with WiFi/Bluetooth it's $6, mechanical scales are double that at $12 while also taking up more volume (more pallets and containers). With volume scale and unique designs, your own skin on the apps, and market specific packaging the margins are only going to get be…