Relays 101

eiodotcom —  May 23, 2012 — 3 Comments

Today’s Eio post is on relays.

What is it?

A relay is an electromechanical device that uses an electromagnet to open or close a switch. In other words, Chet Walters says “a relay works this way: Your switch ‘turns on’ the relay.  The relay ‘turns on’ your accessory. A relay draws very little current through your switch which protects your switch from burnout.  The ‘turned on’ relay can switch a much larger current and not burn out.”

How a relay works. says there are four parts in every relay: an electromagnet, an armature, a spring, and a set of electrical contacts. In essence, when you turn the switch on, it sends electrical current through the circuit and powers the electromagnet. The electromagnet then attracts the armature which acts as a second circuit and completes the circuit so that the light (or electrical appliance) turns on. When you turn the switch off, the armature retracts and makes the circuit incomplete, so that the light (or appliance) turns dark.

What are Relays Used for?

Relays have many uses. Their primary functions include separating AC and DC currents and multiple switching functions, such as delay or signal conditions.

They are used in many electronic applications, such as domestic appliances, air conditioning and heating, lighting and building control, and automotive electrics.

So check out some of Eio’s popular relays:

Velleman Relay Card with LED light switch indicator

Panasonic Power Relay

Velleman Multifunction Relay Switch (includes timers, switching, flashing, interval, random switching)

See also:


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