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 ...
The relay is driven using an NPN transistor (BC547), which allows a small control signal to safely switch a relay. This makes it possible to control electrical devices such as lamps, motors, or ...