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How a relay works

What is a relay?

This is a relay.

This is a relay.

Yes, these are both relays.

To show you we’ll use this relay.

This is the relay with its cover removed.

The relay consist of two parts. The white part is an electromagnet as the name suggests. When electricity is applied it becomes a magnet.

When the first part becomes a magnet it pulls in the arm which is the actual switch. The switch itself has three contacts: the centre, the outer and inner. The middle one is called “common”, the outer one is called “normally closed” and the inner one is called “normally open”.

The connexions are either open or closed.

Now let’s see the relay working. The relay is now wired to a safe 12 volts. When it is switched on you’ll see the contact changes over. To make it easier to see an LED has been added. When the LED is on the relay is energized. Now a blue and green LED have been added. When the relay is energized the blue led is on and when the relay is di-energized the green led is on. This happens because the common contact has changed from normally open to normally closed.

You can use a relay to operate something large like this light.

As mention at the beginning this relay is just a smaller version of the larger one. Its layout is different but it does the same thing only on a smaller scale. See what other uses you can find for a rely.

Now you know how it works.

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