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CO2 Level Indicator (4x7 Segment RGB LED Manual Calibration)

This DIY project shows you how to make your own CO2 level indicator, which shows you CO2 concentration (PPM - parts per million) when button is pressed and always on RGB LED shows constantly how good or bad your surrounding air quality is.

The project was done due to COVID-19 which spreads easily when air quality is poor. CO2 sensors with displays are nowadays quite expensive (starting from 120 and above) and if you want to monitor multiple room air quality at the same time then it is reasonable to do few sensors with displays on your own. Making just one costs about 40-60 depending from where you are getting your parts.


1 x Soldering iron
1 x Cutting pliers
1 x Tweezers
1 x Multimeter (optional)
1 x Tin 20-100 cm depending on thickness
1 x CO2 sensor MH-Z19 or MH-Z19C
1 x 7-segment display TM1637
1 x Arduino nano
1 x 5 mm RGB LED 5 mm (common cathode)
3 x 220 ohm resistors (SMD 0603)
1 x PCB
1 x 3D printed case”

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