1. What is a relay?

Have you ever wondered that the occasional clicking sound of a filter coffee maker is? Or when the staircase lights turn off a few minutes after you push the button?


They are relays, electrically operated switches.

Relays are electrical devices that with a certain voltage/current as input they activate another electronic or electrical device. There are many different types or relays; we are going to experiment with switching relays, which are used to control devices such as motors, electrical appliances, lights etc.

One of the main advantages of a switching relay is that it can control a circuit/device, for example 230V AC devices such as fans, lights, heaters and other household appliances,  with the output of a separate circuit, such as a low-power signal of 5V DC. Separate in this sense means that they have different power supply and ground.