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 ...

With the help of this relay, it is easy to energize other (external) high-power blinkers or beepers, if necessary. // PANIC ALARM - ARDUINO // // by T.K.Hareendran // int rlyPin = 12; // Relay Output ...