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

In this quick Arduino tutorial I will explain how you can control a relay using the Arduino Board, one 1K and one 10K resistors, 1 BC547 transistor, one 6V or 12V relay, one 1N4007 diode and a 12V fan ...