As you can see in the schematic the 12V battery (or use other voltages ... When voltage is applied to the coil then the relay switches and now T1 (plus) is connected to contact 2 (and 3) and T2 (minus ...

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 ...