Do you want to have the ability to control a single electromechanical relay for switching loads of up to 24VCD or 40VAC? If yes, then this is the perfectly suitable product for you from Evil Mad Scientist.
Each Relay Shield comes equipped with a single pole- double throw (SPDT) sealed relay which can handle a current load of up to 5A. What does this mean? It means that when current is applied to the coil, it throws a simple change over switch, Why is that? It’s basically to terminate the connection from the normally closed contact to ground and therefore closing the normally opened contact Use them to switch high voltage/ high current devices.
As this is a shield, it’s powered straight from the 5V power supplied by your Arduino, simply slide it into your Arduino or shield-compatible board like the Red Board, and you’re good to go!
The relay shield is controlled through pin Digital 4 on your Arduino via a transistor labeled “Q1”. When output Digital 4 on your Arduino is low, the relay shield will connect the NC pin to the “Common” pin of the screw terminal. When output Digital 4 goes high, the “Coil On?” LED will light up and the relay shield will instead connect the NO pin to the “Common” pin of the screw terminal.
The Relay Shield is sold as an easy-to-assemble kit and includes everything listed below with clear assembly instructions listed in the documents section.