In this video we explore ground fault interrupt circuits and how they keep us safe. Created by Karl Wendt.
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- What do solenoids do exactly?(5 votes)
- Solenoids most often act as electromagnets, meaning that when current passes through them a magnetic field around the coil is created. Transformers also use them to change the potential difference (voltage) through a conductor. In a transformer, current flows through a primary coil, which in turn induces a current in a secondary coil. If the secondary coil has more turns than the primary, the voltage is increased and if it has less turns it decreases the voltage. They are also used in radios to convert the radio waves into a flow of electrons (electricity).(3 votes)
- where did you find an 1875 hairdryer?(3 votes)
- I am pretty sure that you already know this but i am gonna answer this anyway,
the 1875 doesnt refer to the year it was manufactured in, it is a kinda product number, like the "5" in iphone 5.(1 vote)
- At4:14, what is a linear solenoid?(2 votes)
- Linear just refers to the configuration of the solenoid. There are rotary-type solenoids as well that can act as switches, valves and other electromechanical devices. In the video, the solenoid is basically acting as a linear-actuated switch. If the internal circuitry of the dryer gets shorted because someone dropped it in their bath-tub, current is routed through the coils of the solenoid, which creates a magnetic field through the center of the coils (and the outside, but the center is the important part). This pushes the little metal spike out one end and breaks contact with the circuitry running to the actual hair dryer. Thus, the person can live to bathe and blow-dry another day. Preferably not at the same time.(1 vote)
- Near2:53why are PCB's green(1 vote)
- PCBs can actually come in all sorts of colors; it just happens that the vast majority are green. The green stuff is actually a layer called solder mask, which makes soldering the board much easier. There are definitely other colors out there though: Arduino boards are blue, SparkFun boards are red, OSH Park boards are purple, Fritzing boards are white, etc.
Here's an explanation I found online: http://www.4pcb.com/pcb/
"The original masks used a base resin that was a 'brownish yellow' and a hardener that was a deeper muddy brown. When they were mixed together they created a honey brown color that apparently not very appetizing. They tried adding red pigments but it became a rusty adobe color and using blue simply made it a darker brown. None of them were very appealing colors. Since the laminate materials at the time had a green hue they tried adding more yellow and some blue and ended up with an acceptable green color. It became the standard color we are still using today."(3 votes)
- At1:42he says hat you shouldn't open a plug without a professional, why not? what might happen?(1 vote)
- I would say only worry about that if you plan to plug it back in. if certain parts are messed up inside the plug it can be a fire hazard, parts may explode, or it may ruin some of the wiring in your house. If you make sure it is unplugged and you won't be plugging it back in you wouldn't need a professional.(2 votes)
- do other plugs do the same thing because some plugs don't have 1 large side and 1 small size ?(1 vote)
- It only depends on what kind of plug fits in. You don't need the one with the large and small, you could do with what you have as long as it fits in the right way.(2 votes)
- what do you mean by the plug being able to sense difference enbetween(2 votes)
- at1:09the term "short" is mentioned, and then again a few seconds later.
please may I know what is a short?(1 vote)
- The term short in this context means to short-out; it basically occurs when a conductive element comes into contact with the circuit board, allowing voltage to bypass all resistors and capacitors. When this happens, this is bad. The voltage will rush through the element instead of the board with almost no resistance and destroy many, if not all, components. The solenoid safe-guards from this issue.(2 votes)
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.