Why use a relay with an Arduino board?
Individual applications will vary, but in short – a relay allows our relatively low voltage Arduino to easily control higher power circuits. A relay accomplishes this by using the 5V outputted from an Arduino pin to energize an electromagnet which in turn closes an internal, physical switch attached to the aforementioned higher power circuit. You can actually hear the switch *click* closed on even small relays – just like the big ones on street corners used for traffic signals.
Another reason to use a relay is for electrical isolation. The switching contacts of a relay are completely isolated from the coil, and hence from the Arduino. The only link is by the magnetic field, represented in the diagram by a dotted line.
So this provides a really safe way of controlling big, mean devices which handles higher voltages by preventing a reverse flow which could potentially fry and damage the microcontroller.
In my next post I’ll explain in detail how to control and handle higher power requirements using microcontrollers. Keep watching this space
Until next time