Home air monitor is based on the development board NodeMCU (CP2102 version). It includes a temperature sensor - ds18b20, a humidity sensor - HTU21D, a carbon dioxide sensor MNH-Z19. It is also possible to connect one more i2c sensor and a radio module to 433 MHz.
PCB is used to control 3 typical CPU fans with mounted high-power LED chips according to temperature and tach sensors
Relays are used to power-off LED drivers in case of fan failure or overtemperature condition