Club 80-90 Forums

You start watching this not quite sure where he's headed but actually its a spot on (and easy) explanation of how a relay. works:

https://www.youtube.com/watch?v=5Iujs94re_U" onclick="window.open(this.href);return false;

A relay..
Allows a small load carrying switch to operate a high current circuit.

Because of ERGONOMICS; vehicle designers put all the electrical controls within easy reach and access of the driver. Some of these controls switch high current circuits: without relays the dashboard would look like something out of Frankenstein's laboratory, with massive 'THROW' switches to carry the high current to circuits like the heated rear window and headlamps. With relays, small dainty switches operate these high current circuits 'remotely' taking away the need for heavy thick wiring and large cumbersome switches close to the driver.
To be honest, relays are one of the harder things I have to describe to my students.

Martin

What's the difference between a relay and a solinoid ( higher current in the solinoid?)
Old Tv engineers joke,why are you insulate ? Because I've got 2ohms to feed!

A relay is a switch operated by a solenoid.

dave friday wrote:( higher current in the solinoid?)

lower current in the solenoid, higher current is switched by the solenoid operating the contacts.

Why the different words then?

dave friday wrote:Why the different words then?

A solenoid on it's own is an electromagnet.
It can be used to pull in an electrical switch as in a relay, or to provide some other mechanical pull.
Just to confuse things, the solenoid on a starter motor pulls in the starter motor contacts so should really be called a relay. But it isn't.

Confused? Of course we are,if we add another winding we can make a push pull solinoid! Or a kind of stepper motor!

dave friday wrote:Why the different words then?

Because they work differently.
A relay uses an electromagnet to attract the relay contact arm to it to close the switch.
A solenoid moves an iron core in a linear motion through the windings to push/pull the contacts together.

Thanks Bigherb that makes sense, moving pole piece in a solenoid,non moving pole piece in a relay.
ta.