Here, we learn what relays are and how they can be used to control everyday electrical/electronic appliances. Also, to make them useful, we will connect them to the Arduino and create a
Blink.ino program, except this time it will be your lamp that will be turning on and off.
A relay is basically an electrical device, usually consisting of an electromagnet, which is activated by a passing of current in one circuit to open or close another circuit. You could think of it as a switch that requires current to turn on or off.
Why can't we simply connect a pin of the Arduino to the switchboard, ...