This is an easy tutorial showing how you can control the brightness of an LED or adjust the speed of a DC fan using Arduino Board, a small BC547 transistor and a potentiometer. In my example the whole ...

Below you can see a “CIE1931 Fade” Arduino sketch by Tom Igoe (https://tigoe.github.io). The sketch takes input from a potentiometer and produces a fair LED fade, using the CIE1931 perceived lightness ...