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 ... as a voltage divider ...

Here is a simple, yet useful circuit of an Arduino 4-digit 7-segment LED display unit. The module used here is ... D13 of the Arduino is reserved for the decimal point segment. The 10K potentiometer ...

Each row of like colored LEDs is brightness controlled by a digital potentiometer ... and SWITCH4 on the PC board (5 and 6 on the schematic). Arduino pins 6, 7, 8, and 9 should connect to the ...