In the case of the Relay Shield, the two “Control Circuit” terminals for each of the four relays are controlled by only one Arduino Digital I/O pin. Pins 4, 5, 6, and 7 control relays 4, 3, 2, and 1 ...

The Relay Shield provides a solution for controlling high current devices that cannot be controlled by the Arduino's Digital I/O pins due to their current and voltage limits. The Relay Shield features ...

When the button is pressed the Arduino board will put pin 2 in HIGH state, meaning 5V on pin 2. This voltage is used to drive the transistor that will switch ON the relay and the load (in our case the ...