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I use a Esp8266 microcontroller reading a MH-Z14A NDIR CO2 sensor [1] and a Laser PM2.5 HM3301 from grove [2]. Pretty easy to code up in C. Once tge sensors data is read, the esp sends the it over the MQTT protocol on wifi to home assistant which puts them in SQL db and does plots and stuff.

[1] https://www.winsen-sensor.com/d/files/infrared-gas-sensor/mh...

[2] https://www.seeedstudio.com/Grove-Laser-PM2-5-Sensor-HM3301....

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My DIY sensors[1] (temp/humidity) are running on attiny84 and 3xAAA batteries, which I really like as they last for about a year (sending updates every ~1 minute and then sleeping).

But because I'm not using a voltage regulator, since that would mean losing the very nice onboard voltage monitor, it's been really hard to find some CO2/PM2.5 sensors that can work from ~5V to ~3.4V.

> Working voltage 4.5 V ~ 5.5V DC

> Operating Voltage 3.3V / 5V

Guess I need to keep looking, but thanks for linking the specific models!

[1] https://ambient.emilburzo.com/#overview

Interesting as another proj

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