electronics!!!

[smokeu400]

hey guys i need help with electronics.......i need to know when the electronic relay was invented, what does it do, what diffrent types are their,and any other info you guys can find or know. thanks alot, and now i am off to look them up myself

[wilkin250r]

I don't know when it was invented, but I can tell you a LOT about relays.

A relay is just a switch, much like the light switch in your house. Only instead of flicking it "on" or "off" with your finger, you switch a relay "on" or "off" by applying electricity.

A regular switch has two terminals. When the switch is "on", electricity can flow from one terminal to the other.

A typical relay has four terminals. Two terminals act just like the switch, they are called the contacts. When the relay is "on" electricity can flow between the contacts. The other terminals are used for activation, for turning the relay on and off. They are called the coil. When you apply electricity to the coil, the relay turns "on".

I can give you a lot more info, how much do you need?

[smokeu400]

i need as much as you can give....i have 2 write a 2-3 page report on them......
i need all this:
history of component
description and definition
symbols, letter abbreviation, and units or measurment
opperation of component
testing component(in and out of circuit)
pictures and examples

[derekhonda]

wilkin just gave you a **** load of information, couldnt you just look up the rest of it and/or expand off of his ideas?

[AshYFZ450]

Here is some good infoNavy Electricity and Electronics training series (NEETS) (http://www.phy.davidson.edu/instrumentation/NEETS.htm)
Go to Module 3, chapter 3, page 3-22

[wilkin250r]

I can't help you with the history, but I can tell you all about how relays work, different types, and how to test them. I'm not going to write your whole report for you, but I'll give you a head start.

This is a typical relay, with the cover off. Remember when I said the typical relay has four terminals? I lied, most of them have five terminals. This particular one has eight terminals, but we'll only focus on five of them.

[wilkin250r]

The terminal on the far left is the coil. It is literally a coil of wire, often with several thousand turns. It creates a small electromagnet. The other terminal to the coil is on the opposite side. The big white thing in the middle is the actual coil of wire. Applying electricity to this coil actually creates a magnetic field that goes straight through the center of the coil.

The drawing is very crude, because I'm trying to do it fast.

[wilkin250r]

The terminal in the middle is called the Common.

When power is NOT applied to the coil, the relay is off, and there is no magnetic field. There are two contacts, Normally Closed, and Normally Open. When the relay is off, the common is connected to the Normally Closed contact.

[wilkin250r]

You see the spring at the top. The whole left portion is a hinge. When the coil is "on", the magnetic field pulls the hinge towards the coil, and then the Common is connected to the Normally Open contacts.

[wilkin250r]

If the relay has only two contacts, just open or closed, it's called a SPST=Single Pole, Single Throw.

http://www.kpsec.freeuk.com/symbols/swspst.gif

If the relay has three connections, a Common, Normally Closed, and Normally Open, and it actually switches between the two, then it is called a SPDT=Single Pole, Double Throw.

http://www.kpsec.freeuk.com/symbols/swspdt.gif


It's possible to have more than one switch inside a relay. If it has two SPST switches inside, it's called a DPST=Double Pole, Single Throw.

http://www.kpsec.freeuk.com/symbols/swdpst.gif

The particular relay I have in the picture actually has two SPDT inside, so it is a DPDT=Double Pole, Double Throw.

http://www.kpsec.freeuk.com/symbols/swdpdt.gif

[smokeu400]

wilkin250r thanks you helped alot

[400exrules]

this should be all u need:)


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