These have to be the least accurate things I have ever seen.
The rectangular one is accurate or accurate enough and has been what I used but I noticed files all had cutouts for these round hygrometers…
Well from my 6 pack 1 is within a margin of error to even be useful.
I get they aren’t expensive but seems like a waste of money for this bad.
As an old toolmaker who might have dabbled in accuracy. I just shake my head when people complain about things like this because they think absolute accuracy --an impossibility-- is the important thing, (you can’t afford anything close absolute accuracy), when it’s repeatability that matters the most. Choose the one that repeats the best, toss the rest. Then learn what the “magic number” is that makes you happy to read and need to get the results you are looking for. Learn to apply some bloody “windage”.
Remember: Rick Sanchez is a dumb-ass. And you only need to be 5% smarter than the tool you are using to be successful. So be smarter than the tool and understand the process.
I would not be at all surprised to learn that both the commodity round and rectangular units use the exact same components inside. These surely must be made from jellybean off the shelf parts, and at similar price points to each other neither could possibly be assembled with much care or attention to detail.
I have a six pack of the rectangular ones from Jeff Bezos’ Knockoff Whitebox Emporium. Even all sealed in the same container with each other, they all disagree by a spread of about 15%. I have no idea which of the six, if any, are actually producing an accurate number.
@Krauerking@lemy.lol Hygrometers are only as good as their components. Buying a DHT11/22 or SHT31 from AliExpress ($1-2) alongside an ESP8266/32 and you’d have much better results than buying these “are my cigars dry” pucks.
I’ve had massive differences in readouts in DHT22 from aliexpress. They are really not good sometimes
@callcc@lemmy.world SHT31/41 are better than DHT22 tbf. DHT would have a variance of about 2-5%. It also takes a while for it to stabilize.
Thanks for the tip. The BME280 are also not too bad.
@callcc@lemmy.world True - but it really depends what you’re measuring with BME280/680s though (680>280). As a combination temp/humidity/pressure they’re excellent, but for humidity alone I think SHT gives better “expected” readings than BME.
Someone nerded it out on arduino forums about five years ago: https://forum.arduino.cc/t/compare-different-i2c-temperature-and-humidity-sensors-sht2x-sht3x-sht85/599609/10