What is inside a hair dryer? (1 of 2)

In this video we explore ground fault interrupt circuits and their importance in keeping us safe.

Alright today we're going to take a look at the

Conair 1875 hair dryer.We're going to look at the different systems

and functions inside of it, how it was made and

how it works.

And we're also going to take a look at how they

were able to produce a hair dryer for less than

$8.00 and still make a profit and still stay in

business as a company because that's a very low

price and the way low price. And the way they've

done that is they've reduced a lot of cost and

complexity and we'll take a look at how they've

done that. So the first thing I want to take a look at is

the plug here. This is called a "ground fault

interruptor circuit plug" and it has two different

sized prongs right here. There's a larger prong and

a smaller prong. And that's very important.

The larger prong is the neutral prong and that

means you can't plug this in incorrectly, it has to go in

in only one way. And that means that the power

is grounded properly. So the power always goes

to ground and that's a critical thing in a circuit

like this. So what this plug does it's actually pretty

smart it can tell if there's a power difference

between these two prongs. And that power difference

might occur when the hair dryer was, say, dropped

in water or there was some sort of short that

happened. Inside the hair dryer there are open

electrical contacts that if they're put into water

or some other conductive fluid they'll short out.

And it will cause the, you know, it'll electrify the fluid.

And in the past that was a huge problem because

people would get schocked or electrocuted and now

it's not as big a deal because we have these ground

fault interruptor circuits. So let's take a look at what's

inside of that. And I've already popped this apart to

some degree. I'm going to see if I can get it the rest

of the way here. Now I want to say one thing really

quick here from a safety stand point:

It's absolutely critical that you DON'T take apart

any plugs ever without a professionnal! And if you do

have a professional and you do end up taking apart

a plug like this make sure that you never ever

plug it in! It's totally unsafe. So this is a plastic

moulded housing it was injection moulded.

There were two pieces of steel that came together

and the molten plastic was injected and you can see

there are little pin marks right here. And pins came in

inside the mold and pushed this part out.

And then there's a little plastic piece here with a

spring and that's for the test switch.

So the test switch pushes on this part right here

on the printed circuit board and the reset switch

is right here. So you push on the reset switch

and it will reset it so if it gets triggered you can still

use your hair dryer again later.

So one thing I want to take a look at here is the

printed circuit board here. So we've got a lot of

really cool things happening on this printed circuit

board. It is made out of fiberglass.

It's got a thin layer of copper applied to it.

And then on top of the copper is a layer of lacquer.

(The copper) Before they put the copper layer down

they actually etch away parts of the copper. So

there's places where there is no copper and there's

places where there is. And those places where the

copper exists are called traces and they function

like little tiny wires. They're supper flat and compact

and allow you to get a lot of stuff in a very

small space. Which is why we use a little

printed circuit board like this. And you can see on

here we've got a little tiny capacitor that's called a

surface mount capacitor and a little resistor.

Remember a capacitor stores a charge and then

releases it and a resistor will resist current flow

and that can be used to protect different parts of the

circuit. And this right here is

this part right here is called and integrated circuit.

And it actually takes commands from things on the

back takes information from things on the back

and decides what to do with it.

So this thing right here is called a toroidal ring

or a copper coil and it basically can sense the

difference between these two lines.

And so when there's a significant voltage difference

a few milliamps even

it can tell and it sends information to the

integrated circuit here. And then the integrated circuit

tells this guy which is called a solenoid

it's a linear solenoid.

But it sends electricity to this and it causes this pin

to pop. And when the pin pops, it breaks the circuit

the electrical contact, the connection in the circuit.

So there's no chance that you can get shocked there.

And there's a couple of really neat interesting parts

on this board. We've got a

this is a dialectric capacitor.

And then we have another capacitor right here.

And you can see right here this is a ceramic

capacitor this little sort of rust colored one.

I'll take this out so you can see it better.

And this is called a transistor so it can function

like a switch in a circuit. And this is called a

varistor or a variable resistor and it can protect the

circuit from high voltages and things like that.

It's a non-linear resistor in other words as the

current flow changes the resistance changes and so

it can protect your circuitry there.

And if you look on the inside you can see the

back side of the plugs or the prongs I should say.

And those are just brass pieces with wires that

go to the circuit soldered on.

And then this part of the switch housing

or I should say the plug is also made out of injection

moulded plastic. And then we have the wire that

comes down here and there's this protective rubber

piece on the wire so that the wire can flex back-and-

forth inside of the housing without wearing out.

And if you look right here here's a warning. It says:

unplug it do not remove this tag.

They still want to warn you that it's definitely not safe

to drop a hair dryer into water.

This is a safety precaution but it's not a good idea

to ever put the hair dryer near water because

it is an electrical device with open contacts

on the inside.