I used an LCD shield to display the current temperature and speed of the fan, but you can use the circuit without the LCD ... The LM35 temperature sensor and red led are powered with 5V from the ...

As you can see in the schematic all three TC74 sensors have their SDA and SCL pins connected in series to pin A4 and A5 on the Arduino board. The two 4.7K pull-up resistors must be used when using I2C ...

It runs on an Arduino MEGA 2560 PRO (or similar microcontroller) and supports a wide array of additional hardware including pressure transducer, water level sensor, flow meter, OLED display ...