In this video we go inside a tap light to discover what is inside and how it works. Created by Karl Wendt.
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- These reverse engineering videos are neat. When will there be more of them?(60 votes)
- At3:08he talks about an iphone app that allows you to figure out the resistor type, does anyone know what that is called? Thanks.(16 votes)
- It's a free app called Resistor-Color Code. http://itunes.apple.com/us/app/resistor-color-code/id351246356?mt=8(20 votes)
- Whats LED mean?(4 votes)
- LED or Light Emitting Diode are like light bulbs except are diodes which means that they only permit the electricity to flow in one direction.(18 votes)
- What is polypropylene plastic or abs plastic mean and what are the differences?(6 votes)
- Plastic is made out of carbon chains. The difference between plastics is determined by the structure of the chain.(10 votes)
- what is styrene and what dose that mean someone please answer my question(3 votes)
- how does he know what kind of plastic it is?(4 votes)
- He can tell what kind of plastic it is by looking on the plastic and finding the abbreviation PP which stands for Polystyrene and he can also tell because different plastics have a different texture and properties(2 votes)
- When checking the order of colors on the resistor, how do you know which side to begin from?(2 votes)
- when you look at the resistor there should be 3 or 4 colors grouped on one side and 1 or 2 colors grouped on the other side with a decent gap between the two groups. you put the group of 3 or 4 on the left then you read from left to right.(2 votes)
- A 56 what? (3:47)(1 vote)
- A 56 ohm resistor. Ohm is the unit for electrical resistance (http://en.wikipedia.org/wiki/Ohm), which is a measure of how hard it is for electricity to flow through something.(3 votes)
- Why the wires are of different colors?(1 vote)
So today, we're going to take a look at the tap light. We're going to see what it's made out of and what's inside of it. You just push it and it lights up, produces a nice warm glow, and push it again to shut it off. So the tap light looks like an opaque, acrylic dome here that allows the light to spread out in a nice, soft glow. And then it has a styrene-- this is a polystyrene surround or bezel. So we're going to go ahead and take the screws out. There's just four screws. These are Phillips head screws. And they are zinc-coated steel. We'll take those out. We've got a couple of them out. There's still two left here. I'm going to leave the batteries in place, because I want to show you what it looks like with the top off when the light's on. OK. So we got our screws out. And this is the battery holder. You got four double A batteries there. And so we'll lift the bezel off. And here's the top portion. And this is the top cover. And then we've got this light reflector. And you'll notice that it's not perfectly clear. And that's intentional. That allows for the light to bounce around more and because it bounces around more and goes through these opaque surfaces, it is more diffuse. And so the light comes off as a softer glow rather than a very harsh, sharp, intense light. So this is what it looks like without the cover. And this is what it looks like with it. And you can see how that helps to just soften the light and spread it out. And if we take this part out-, I'm not sure who shows up on the camera, but the light is more intense here. And this, again, helps to continue to scatter that like to make it a softer glow. All right. So let's take a look at the parts inside here. So we've got some springs. And these springs cause the dome to return to its regular position. And so we have three different springs here. We'll remove those. And then we have a light emitting diode. And this is a white light emitting diode. And a light emitting diode or any kind of diode requires that current travel in one direction. So it basically acts as an electronic or a digital valve to keep the current flowing in one direction. So I'll move the light blockers there. All right. So the other thing is in order to operate in LED, you need to have or one of these guys. And that's called a resistor. Now, resistors exists, basically, to keep too much current from flowing to the LED and causing it to burn out before it's supposed to burn out. So one of the things I have been able to do is to use my iPhone to find out what the resistor code is. So it's really a handy way to do it. It used to be you'd have to look it up or just memorize what the different color band codes meant. But this particular resistor, it's got a green band. So we'll put it on green. There we go. And it's got a-- it looks like a navy blue band, and a gold band, green-- oh, wait. Actually, there's a black one. Sorry-- and then the gold one. There we go. So this is a 56 ohm resistor. And that's the amount of resistance that that resistor provides. And the switch right here is just a momentary switch. All right. Sorry. It's not a momentary switch. It's a continuous switch. So that means when you push it down, it stays down. And when you let it up, it stays up. So the light will stay on after you push it. And the circuit is extremely simple. Basically, you've got the power from the batteries. It comes in through the loop here and the switch basically opens and closes and stops the power flow. Or when you push down on it, it closes and allows the power to flow in the continuous loop there. And so that's what's inside of a tap light. Let's take the batteries out really quick so. These are double A's. And now, it looks like this back panel here was injection molded. And you can see the ejector pins there. Those are the pins that push it out of the mold. And so it looks like it was injection molded. And I would say-- it doesn't have the plastic designation marking on it, but I would guess that it's probably either polypropylene or ABS plastic. So you can see in here, these contacts inside here are probably made out of-- I initially thought that they were made out of steel. But let's take a look. We've got some magnets here, so we'll take one of our magnets and-- I don't think they are. So they're probably brass contacts, because the magnets are not attracted to them. So it's not a ferrous metal. So then we've got this loop here. And this plastic loop prevents the positive terminal on the battery from slipping below the contacts. So it stays in constant contact and keeps everything together. And you can see there's another one on this side. And that's pretty much it. Oh, and there's also a feature right here so that if you have a screw or a nail on your wall, you can put the tap light in and just hang it like that. But that's pretty much the tap light.