Love it or hate it, wiring is a part of any project car. You may loathe the idea of installing relays, but without them, wiring would be much more difficult. HOT ROD ...
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 ...