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Relay Shield

Kingston hackSpace

A relay, as its name suggests, passes on (relays) a signal, they are categorized like switches that separates high voltage devices from low voltage devices. It contains a coil of wire wrapped around an iron core. When electricity runs though the coil, the iron core exerts a magnetic force, which pulls a lever, which pushes or pulls a springy strip of metal, closing two contacts. So as long as electricity runs though the coil, the relay is “energized” and its contacts remain closed. When the power stops passing though the coil, the relay lets go and the springy strip of metal snaps back into its original position, opening the contacts.

We use relays for high current applications where a switch may burn out under high current. Also relays can be controlled electrically whereas switches can be only operated mechanically.

IMPORTANT: Relays can work with high voltage, so please be very careful and don’t electrocute yourself! Relays have 6 connections all together: 3 on one side and 3 on the other. One side is responsible for the high voltage (this is the side you don’t touch once connected to the power) and the other for the low voltage. The high voltage side has (VCC), (GND) and (S); most of you will be using VCC and GND only, to connect a bulb or heavy motor. The other side of the Relay has (VCC), (GND) and (S) this will be connected to Arduino or any other microcontroller. (VCC) to 5V, Ground to (GND) and (S) to one of the digital PWM pin on Arduino, the signal pin will control the bulb or motor you have wired on the other side of the relay.


  • to borrow a relay module, click here