I'm a big fan of the AirGradient. They used to have really cheap DIY kits available: either $19 for the PCB + enclosure alone (with the assumption you already have the other parts or will buy them off aliexpress) or $96 for everything. Looks like the current kit is $138. If that's too much, you might be able to make it cheaper by downloading the KiCad and STL files off their website [1], getting PCBs printed elsewhere, 3D printing the case, and sourcing the rest of the parts from aliexpress. When you do it that way, you can also omit any sensors that are not of interest to save money, and perhaps add them in later.
Ya, my AirGradient ONE is $200 and has been one of the best investments in my home. Using it, I discovered how the drying polyester clothes wrecks the indoor air quality and how not to burn baking oils by controlling temps better.
Drying polyester clothes releases CO2 to unhealthy levels?
Probably referring to particulate matter. The AirGradient measures PM2.5. I happen to have an air purifier near my W/D and it catches a lot of lint in the prefilter.
I have one that uses these sensors though I made a variation of this in a different layout and with a different power system (usb c and one that is powered off 12v). Wonder if JLPCB is affected by tariffs. I’d love to do a new board.
I've been having problems with my devices, though. The reliability sucks, they lock up all the time.
Additionally, the OLED screen needs to shut down in the dark. I added a VEML lithgt sensor to my devices for that.
I haven't had any issues with lock-ups.
The LEDs and screens can be adjusted (or turned off) on a schedule with the latest firmware.
Interesting. I have been running three of their devices of different generations in my house for several years now with no hangs.
No idea why. I tried to change the power supply, and even slightly overvolt the power (to 6V from nominal 5V).
The light strip they added to the new devices is fun. You get a free nightlight too.