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What is inside a hair dryer? (2 of 2)

Video transcript
Let's take a look at the hair dryer itself. And as we come up the plug, here, this is where the power comes in. We have another protective rubber piece and a little holder here that's molded in, which is kind of nice. So you can hang your hairdryer in the bathroom, if you want to. And then, we have our switch. So this allows us to turn the power high, low, and off. And we have these little molded patterns, here. And then our funnel, that funnels the air through. And you can see there's a screen on the back. And that helps to keep things out. So let's take a look at what's inside. We're going to use a Phillips head screwdriver, here. And just remove these screws. These screws are plated. They're made out of steel. And I believe they are chrome plated because they're super shiny. And the reason they would do that is that hairdryers are often used in very moist environments, like bathrooms and things like that. And so the screws, if they're made out of steel, are going to rust. And so you want to put a coating on them that won't rust, and chrome won't rust. So that protects them. And because those screws are visible, they may have also used a bright finish chrome because it looks better than, say, a painted screw would. OK, so let's take this apart. And it also provides a little better corrosion resistance than paint does. All right, so let's take this apart, here. And if you look on the inside, you can see that, again, this was an injection molded part. The mold came together, like this. And plastic was injected. And then, injector pins-- which you can see the little marks right here-- pushed on the part and caused it to drop out. And you can see that this material is called PP. It stands for polypropylene. And the ejector pin marks are right here. So they're scattered throughout this, to evenly push on it, to get it to come out. There's all these features on the inside. They provide structural rigidity and stiffness. They also provide a mounting location for the fan housing, here. And the screen in the back looks like it was put on with a machine, pressed against the back of the housing, here, where there's the vent. And it looks like the plastic was heated up. And the screen was pushed into the heated plastic, so it's held in place. And that's kind of a low cost way to hold those pieces together. There's no fasteners there. Fasteners add expense. So that's one of the ways they were able to reduce cost. So we'll set that aside, for just a second. And if we come up, we look up inside the switch here. This is where the power comes in. This part, right here, is very interesting, as well. A lot of times you'll see manufacturers will actually tie the power cord in a knot. And in this case, there, they're not tying it in a knot. They run it through over this screw boss, or place that the screw goes in. And the reason why they do that is so that you can't pull it out. And you definitely don't want to have a condition where the wire can get pulled away from the switch and maybe have a free electrical contact in there that could touch things, and short out, and maybe just cause your hairdryer to stop working. So that protects you there. So that's another safety thing. So we'll go ahead and pull this switch out. You can see that these are plastic brackets that the switch fits nicely into. It holds it steady, in place. And the switch has three different settings. And let's see if we get that to where you can see it. The switch is 16 amps at a 125 volts, or eight amps at 250 volts. So this switch can handle a fair amount of current. And if you see, there's a number of different wires leading out from the switch. And they run to the heater. And this wire, right here, is connected with this brass connection. And since the connection is open, there's a clear piece of plastic that's gone over that. And that prevents it from contacting the other parts of the switch and shorting out the circuit, or creating a problem. So we have another little tiny screw, right here. We're going to take that screw out. And it's the backside of the switch, here. And so that held the front side of the switch in place. That's just, again, an injection molded piece of plastic. And then, the backside slides in this channel, right here, like that. And it interfaces with the switch itself. And it's just a piece of molded acrylic that fits against the switch and allows you to transfer the movement from the outside to the inside of the unit. All right, so we've got a fan here. We've got these two santoprene pieces. They're just like rubber molded accent pieces. And I think they're mostly there for just design style. And we're going to go ahead and pull this out, see if we can get the heater unit out. Before we take a look at that, let's look at this. So this is our funnel. And as you know, the hair dryer heats up. So that heat could cause the plastic to get really hot, or soft. And so, they put this piece, in here. And this is called a mica sheet. And it basically protects the housing from getting too hot when the heater heats up. And then if you look on the backside here, we've got a bracket, a little cover. And this is made out of steel. It's just painted steel. And again, it protects things from getting into the heater. It just force fits into the end, down there, so there's no fasteners. Again, it helps to reduce costs. This was injection molded, just like this piece was. And the mold came together like this, from both sides. And then there were pins that pushed the plastic out once it had hardened. And so that's that. So if we take a look here, we can see that we've got nichrome wire. So the thing that's fascinating about this hair dryer is that they take this nichrome wire, and they use it as a massive resistor. Because your motor doesn't want the full 120 volts AC that comes in from the outlet. It wants DC power. It needs to run on DC power. It needs to run on 12 volts. So the way they get it down to 12 volts is they use the heater as a resistor to drop the voltage down to 12 volts. So that's kind of an ingenious way of doing that. And then, the heater is made out of these coils, here. And they're called nichrome wire, or they're made out of material called nichrome wire. And nichrome is an alloy of nickel and chromium. And when electricity is run through it, it heats up. And it heats up in a way that is very effective at getting hot when powers run through it. But it also doesn't oxidize. So a lot of times when you heat up other metals, they'll oxidize, they'll rust. And then you get problems with that. This doesn't do that. It just heats up, and then it cools back down and there's no oxidization. So it works really well as a heater. And on the front, here, you can see there's this 90 degree opposed bracket that holds everything 90 degrees apart, which keeps everything working as far as air flow and stuff like that. It also holds this mica sheet separated. And then you can see on the inside, we have these brass contacts. And they're little brass rivets. And they distribute the power around to different parts of the heater. And right here, this part is a bimetallic strip. So that bimetallic strip is made out of two pieces of metal. And what it does is when the metal is heated to a certain point, it causes the bimetallic strip to bend. And so one piece of metal has a different expansion rate than the other piece of metal. And it causes the strip to bend. So maybe, this one on the outside-- if this was the bimetallic strip. This one expands faster than this one, and it causes it to bend. So you could have two different types of metal like, say, an alloy called invar and another piece of metal called copper. And the copper is going to respond to heat at a certain rate, and it's going to expand. And the invar is going to not expand nearly as fast. And it's going to cause that switch to open up. And that will shut down the power to the heater. So if it gets too hot, the bimetallic strip will expand, and it will pull itself away from the contact and shut down the electricity to the heater. You can see, we also have a diode, right here, in line. That just controls the flow of electricity. . It's like a little electrical valve. And then we have a thermal resistor, here. I'm sorry, a thermal fuse. This is called a thermal fuse. And the thermal fuse, basically, is another safety precaution. If temperatures get too high, the fuse will blow. And it will shut down the hair dryer and prevent the housing from melting, or the hair dryer from getting too hot and potentially blowing air out that could burn you. And so, remember, the heater has functioned as a resistor. And it has dropped the voltage down to 12 volts. But it's still AC power, which means alternating current. Alternating current, basically, functions as a sine wave, like this. It flows back and forth. And the motor that we have here is designed to run on direct current, so just flowing in a continuous loop. And the way that this unit, this hair dryer, deals with that is it has these four diodes. You can see them-- one, two, three, four. And so what those four diodes do is they function like a bridge rectifier. And they convert the AC power into DC power. And they do it in a very low cost way. The diodes are very inexpensive. So once the voltage is dropped and the power is converted, the fan begins to spin. And so, the fan turns. And it pulls air in. And you can see these louvers, right here. They help with the air flow, so that it blows past the heater in the right way. And the inside of the motor-- I'm not going to take the motor apart in this video. We'll do that in another one. But inside the motor is a copper winding, and there are some magnets. And the electricity causes the motor to spin. And it pulls air through, past the heater. And the reason why you do this is that heated air, or hot air, can hold a lot more moisture than cool air. So it dries your hair a lot more quickly. Old hair dryers used to be about 100 watts, or maybe just a little bit more than that. So it took them a long time to dry your hair because they just didn't have the same amount of heat energy that this one does. At 1,875 watts, this is about as much heat energy as you can generate in a given 20 amp circuit. So it's pretty close to the limit. In any case, this is, again, a plastic propeller. And it looks like an acrylic housing, here, or clear plastic housing. And then we have another bezel. And this just helps to direct the air flow and also hold the motor in place. But that's the Conair 1875 hair dryer. And I hope you've enjoyed it.