You can use shift register ICs like 74HC595 to connect more leds and free the pins on your Arduino board. The only interesting part inside the code is at line #18 inside the for() loop where we put ...

We set the potentiometer pin as 0 (A0 on the Arduino Uno board), the CONTROL variable is the voltage that is used to cotrol the led brightness of the speed of the fan. In the setup() function the ...