The second version of the Air Quality Monitor

Some time ago, I described a device for monitoring indoor air quality, which can be made independently from parts ordered at a well-known Chinese online store.

And now a new version of the device has appeared.


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Improvements in the new version are small, mainly related to the firmware. But the addition of a new BME280 sensor significantly expanded the functionality of the device.



Information on temperature, humidity, and atmospheric pressure is now available.


For those who assembled the device of the first version, its refinement and improvement will be the simplest task. Just add a new sensor and upgrade the controller.

The new sensor is connected via the I2C interface directly to the already installed clock.


With a BME280 sensor, the device will switch the panel showing dust measurement parameters to the temperature, humidity, atmospheric pressure display mode every 15 seconds, and 15 seconds back to the dust display mode.



The BMP280 sensor is removed from the case so that it would not be influenced by the heating of the other components of the device. In the picture this is a small radiator in the upper left corner.
For the remaining sensors, a fan is used, which slowly blows through the case.

Even in this version, it became possible to use the device without a formaldehyde sensor. In the old firmware without this sensor the dust sensor did not work.

→ Here you can get a new firmware
→ here Archive with script files
→ Here is an instruction on how to assemble such a device yourself.

Instructions on how to flash the controller can be found here .

Electric circuit:

Circuit board:

Further information can be found on my website.