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 ...

However, whenever you are working with Mains voltage, things really must be done the correct way, so here are a few observations, to help out anyone else who may be looking at a similar project. 1.