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Speaker 1: Welcome to tech Stuff, a production from I Heart Radio.

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Speaker 1: Hey there, and welcome to tech Stuff. I'm your host

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Speaker 1: Jonathan Strickland, Diamond executive producer with I Heart Radio, and

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Speaker 1: how the tech are you well today? For a tech

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Speaker 1: Stuff Tidbits episode, I thought I would talk about what

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Speaker 1: diodes are and what they do. So they are one

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Speaker 1: of the basic components of modern electronics. So what the

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Speaker 1: heck are they? I'm sure you've heard of them, even

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Speaker 1: if you're not familiar with electronics, you've heard the term diodes. Heck,

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Speaker 1: l e ED. That's a light emitting diode. You have

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Speaker 1: lots of stuff all around you that has diodes in it.

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Speaker 1: So it's easiest to explain diodes by starting with the

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Speaker 1: kind of of function they fill within electronics. So a

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Speaker 1: die ode is sort of like a check valve in

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Speaker 1: a plumbing system. So a check valve in a in

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Speaker 1: a pipe, for example, will open when water flows in

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Speaker 1: one direction. The water will push against the valve and

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Speaker 1: the valve will lift up and water can flow through.

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Speaker 1: But if the water starts to come back in the

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Speaker 1: opposite direction, then the water is going to push the

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Speaker 1: valve cap back down and the valve will close and

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Speaker 1: the water can't keep going. So this way you can

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Speaker 1: allow water to flow one way through the pipe, but

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Speaker 1: it can't come back, which is important in some types

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Speaker 1: of you know, hydraulic systems, that sort of stuff. So

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Speaker 1: diodes do something similar. They allow electricity to flow in

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Speaker 1: one direction in a circuit, but they prevent it from

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Speaker 1: going the opposite way. Now, a quick word on that.

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Speaker 1: When we talk about current and flow, things get a

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Speaker 1: little confused due to the fact that electrical engineers described

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Speaker 1: current as moving from positive to negative. But if we

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Speaker 1: look at the at current as the flow of electrons,

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Speaker 1: we know that this is the opposite of what actually happens.

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Speaker 1: It doesn't go positive to negative. Electrons move from negative

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Speaker 1: to positive. This is because electrons themselves have a negative charge,

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Speaker 1: which means they're repelled by other negative charges, right like

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Speaker 1: repels like, and opposites attract, So electrons are attracted to

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Speaker 1: positive charges. So if you've got a big old bunch

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Speaker 1: of electrons crammed in together somewhere, they're all desperately trying

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Speaker 1: to get away from each other. But if you then

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Speaker 1: create a pathway where electrons can travel to a place

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Speaker 1: where there's a positive vibe. They're gonna rush through that

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Speaker 1: pathway to get to the positive place because no one

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Speaker 1: wants to hang out at a party where everyone as

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Speaker 1: negative all the time, So they're so eager to get

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Speaker 1: over to the positive place. You could even make them

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Speaker 1: do work along the way. This is the basis of electronics.

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Speaker 1: That electrons move from negative to positive, and along the

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Speaker 1: way you can make them do work because they just

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Speaker 1: want to get to that positive place. Man, they will

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Speaker 1: do whatever it is they need doing, assuming they've got

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Speaker 1: enough behind them to get the job done. Now that's

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Speaker 1: a pretty clumsy analogy, but it does fit anyway. There

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Speaker 1: are a lot of electrical engineering textbooks that talk about

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Speaker 1: what we would call conventional current. Conventional current is the

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Speaker 1: positive to negative flow. This is how Ben Franklin would

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Speaker 1: have talked about it. Uh And unfortunately that's just not

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Speaker 1: what's happening on a on an actual physics level, but

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Speaker 1: on an electrical engineering level. You can often see diagrams

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Speaker 1: that will depict current as flowing positive to negative. So

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Speaker 1: if you ever come across descriptions that talk about current

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Speaker 1: this way, it's from an electrical engineering perspective. And by

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Speaker 1: the way, this does have its uses. It's not that

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Speaker 1: this is this is to a point where it's going

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Speaker 1: to mess you up unless you're looking at a diagram

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Speaker 1: and you're making, uh, the opposite assumption based on the diagram. Instead,

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Speaker 1: it's useful for talking about specific systems. So I don't

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Speaker 1: mean to completely dismiss it, but it is kind of

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Speaker 1: funny to me. But I am going to talk more

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Speaker 1: about the electron flow description of current, So that means

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Speaker 1: going negative to positive, because that's what's actually happening. If

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Speaker 1: you were able to somehow visualize the electrons as they

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Speaker 1: move through the system, that's how it would go. All right,

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Speaker 1: let's get back to diodes. So let's say you're putting

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Speaker 1: together a simple circuit with a diode and you've got

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Speaker 1: a light bulb connected, and then you're going to connect

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Speaker 1: a power source of battery. Now, because diodes only allow

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Speaker 1: current to flow in one direction, if you've installed the

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Speaker 1: diode the wrong way around, it will actually prevent electricity

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Speaker 1: from moving through the circuit and the bulb won't light up.

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Speaker 1: If you flip the diode around, then it allows the

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Speaker 1: electricity to flow through the circuit and the light bulb

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Speaker 1: comes on. So when the diode faces one way, it's

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Speaker 1: behaving like an insulator. It's it's preventing the flow of electrons.

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Speaker 1: If you flip it around, it acts like a conductor.

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Speaker 1: It conducts the flow of electrons um And it turns

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Speaker 1: out the yeah, diode is a semiconductor component. It can

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Speaker 1: act as both a conductor or an insulator depending upon

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Speaker 1: the situation. A diode positioned to allow current to flow

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Speaker 1: is what we call in the forward bias. Forward means

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Speaker 1: that electricity can flow through the diode. If it is

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Speaker 1: positioned to act as an insulator, it is in the

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Speaker 1: reverse bias. It will prevent electricity from flowing in that direction.

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Speaker 1: But how like, what is it about a diode that

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Speaker 1: allows this to happen. Well, that requires a bit of physics, alright.

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Speaker 1: So a conductive material has a lot of what we

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Speaker 1: would call free electrons, meaning these are electrons that are

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Speaker 1: not in fully packed electron shells. They can be boosted

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Speaker 1: out with just a little bit of energy and then

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Speaker 1: be free roaming electrons. But uh that so you just

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Speaker 1: have to add some energy, right and then once you do,

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Speaker 1: then the electrons will start to move through the material

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Speaker 1: and they will be moving towards the most positive area

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Speaker 1: connected to this material. And then if you have an insulator,

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Speaker 1: while you've got electrons that are very tightly packed, right,

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Speaker 1: there's no movement available, like there's no room in the end,

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Speaker 1: so there's no place for an incoming electron to go,

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Speaker 1: and it kind of just bounces off and you know,

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Speaker 1: it acts almost like a force field. Now, to make

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Speaker 1: a semiconductor really useful, we actually have to dope it

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Speaker 1: because semiconductive material has fairly tightly packed UH atoms and

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Speaker 1: fairly tightly packed electrons. So without doping it, without introducing impurities,

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Speaker 1: then you're not gonna be able to easily make it

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Speaker 1: conduct It will act as more of an insulator than

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Speaker 1: a conductor. So we're just introducing something else in there

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Speaker 1: to change up the structure really and you can actually

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Speaker 1: dope semiconductor material in one of two ways. You can

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Speaker 1: dope it with atoms that actually have extra electrons in

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Speaker 1: their outermost shell, which creates an in type semiconductor or

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Speaker 1: negative side. Or you could pack in atoms of stuff

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Speaker 1: that have fewer electrons in their outer shell, which means

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Speaker 1: we they have holes, they have places where electrons could occupy.

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Speaker 1: This is p type semiconductor material. Now, let's talk about

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Speaker 1: silicon to give an example. So a silicon atom has

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Speaker 1: four electrons in its outermost electron shell, but it's an

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Speaker 1: electron shell that can accommodate up to eight electrons. It's

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Speaker 1: just that silicon doesn't have eight and its outermost as four.

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Speaker 1: But if you get a lot of silicon atoms together

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Speaker 1: and they form covalent bonds with one another, then each

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Speaker 1: silicon atom is going to bond with four other silicon

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Speaker 1: atoms and they're gonna share outer most electrons, so that

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Speaker 1: each atom, if you were to look at it and

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Speaker 1: just kind of ignore the fact that there are atoms

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Speaker 1: around it, it it would appear that there are eight electrons

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Speaker 1: and net outer most shell and then would be all

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Speaker 1: full up. So, in other words, when silicons all together

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Speaker 1: as a as a material, as opposed to a single atom,

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Speaker 1: then it's acting like it's got full electron shells and

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Speaker 1: its outermost shell. So what you want to do is

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Speaker 1: introduced something else, like phosphorus, which has five electrons in

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Speaker 1: its outermost shell. So silicon has four, phosphorus has five.

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Speaker 1: If you start putting phosphorus, if you dope phosphorus into silicon.

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Speaker 1: Then these silicon atoms, some of them are bonding with phosphorus.

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Speaker 1: But that means there's this extra electron that has nowhere

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Speaker 1: to go, right, because you only have enough room for

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Speaker 1: four of those electrons in that oldermost shell to bond

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Speaker 1: with other atoms. The fifth one is kind of loose

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Speaker 1: on its own. So now you have electrons that could

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Speaker 1: easily freely move through this material. Then, if you want

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Speaker 1: to make a P type semiconductor, you dope silicon with

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Speaker 1: atoms that have fewer than four electrons in their outermost shells.

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Speaker 1: For example, aluminum as three. So aluminum bonding with silicon

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Speaker 1: means there's gonna be an extra space for an electron.

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Speaker 1: You get a hole there. Uh, And so you have

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Speaker 1: this N type or negative semiconductor material that has an

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Speaker 1: excess of electrons and thus has a negative charge. And

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Speaker 1: then you have a P type semiconductor material that has

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Speaker 1: an excess of electron holes, and we describe this as

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Speaker 1: having a positive charge. So if we put IN type

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Speaker 1: against P type, we create a diode. So you have

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Speaker 1: N type semiconductor material on one side and P type

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Speaker 1: semiconductor material on the other side, and where the two

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Speaker 1: meet is called the P n junction. We'll describe its

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Speaker 1: function after this quick break. Okay, so we have the

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Speaker 1: P n junction where the P type semiconductor material comes

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Speaker 1: into contact with the N type of semiconductor material. What

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Speaker 1: happens then, Well, if you remember, the N type semiconductor

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Speaker 1: or the N type side of the diode has an

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Speaker 1: excess of electrons, the P type has an excess of

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Speaker 1: electron holes. So you would think, oh, well, then all

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Speaker 1: the electrons are just gonna move, all the free electrons anyway,

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Speaker 1: the excess ones are going to move from the N

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Speaker 1: type side to the P type side, and it'll just

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Speaker 1: equalize out. That's not exactly what happens. What does happen

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Speaker 1: is some of the electrons do move over from N

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Speaker 1: type to P type, some of the holes move from

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Speaker 1: P type to N type, and it creates what is

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Speaker 1: called a depletion zone at the P N junction. It

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Speaker 1: creates this electric field, and that electric field has a

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Speaker 1: charge there that prevents more electrons from N type to

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Speaker 1: move over to the P type side. So it's like

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Speaker 1: there's this this force field. It's a weak force field,

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Speaker 1: but it exists, and in order to get through it,

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Speaker 1: you have to add more energy to the system. But

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Speaker 1: without that added energy, the electrons just can't make the jump.

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Speaker 1: If you think about it, it's kind of like let's

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Speaker 1: say you're well, you're a kid, and you're running around

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Speaker 1: in the woods and you come up on an old

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Speaker 1: like little dry creek bed that's created a ditch, and

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Speaker 1: the ditch is not wide, but it's not super wide.

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Speaker 1: If you get a running start, you can jump over

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Speaker 1: that ditch. But if you were to try and jump

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Speaker 1: just from a standstill, you never make it right. You'd

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Speaker 1: fall into the ditch. You have to have enough energy

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Speaker 1: to make it all the way across. That's the same

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Speaker 1: way with these diodes. Without that energy, the electrons aren't

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Speaker 1: going anywhere. They are essentially blocked by the depletion zone

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Speaker 1: and the electric field that it creates. All right, So

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Speaker 1: then if we then attach the P type side of

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Speaker 1: the diode, the annode side, to the paw stive end

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Speaker 1: of the battery, and then we take the cathode side

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Speaker 1: of the diode on the N type and we attach

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Speaker 1: that to the negative side of the battery. Well, now

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Speaker 1: the battery is providing enough voltage, enough pressure, enough energy

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Speaker 1: to push those electrons from the inside over to the

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Speaker 1: PA side, and then they continue they're attracted to the

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Speaker 1: anode because the anode is positively charged. Now that it's

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Speaker 1: connected to the positive terminal of a battery, and you

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Speaker 1: get the flow of electricity, And as long as the

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Speaker 1: battery is still attached, it's going to continue to provide

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Speaker 1: that voltage that will allow the current to continue to flow.

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Speaker 1: So electric electrons will continue to go into the N

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Speaker 1: type side and push over to the P type side

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Speaker 1: and then continue their journey over to the positive terminal

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Speaker 1: of the battery. And it'll do this till the battery

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Speaker 1: runs out of a charge or essentially doesn't have enough

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Speaker 1: voltage enough energy to push those electrons over the depletion zone.

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Speaker 1: But then what happens if you turn the battery around, right?

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Speaker 1: What if you what if you put the battery in backward, Well,

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Speaker 1: now you're gonna have these opposite charges. You're gonna have

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Speaker 1: a positive charge over at the cathode side, over at

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Speaker 1: IN type side of the diode. You're gonna have a

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Speaker 1: negative charge over at the anode side, over the P

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Speaker 1: type side of the diode. And that negative charge on

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Speaker 1: the anode is going to attract all the holes over

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Speaker 1: to that side. The positive side over at the cathode

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Speaker 1: is going to attract all the electrons to that side.

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Speaker 1: The middle of your diode is going to become a

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Speaker 1: much larger depletion zone. So in other words, there is

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Speaker 1: now a much larger barrier that you have to jump.

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Speaker 1: It's like that ditch that you came across in the

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Speaker 1: woods has turned into the Grand Canyon. You are just

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Speaker 1: not gonna make it across that ditch no matter how

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Speaker 1: fast you run, except with diodes it's not quite the same.

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Speaker 1: So with diodes, you can create enough voltage to jump

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Speaker 1: that barrier. The problem is when you do this, then

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Speaker 1: you kill the diode and potentially you fry whatever circuit

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Speaker 1: it was connected to because you've you've added enough voltage

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Speaker 1: to overcome this depletion zone. But for normal operation, that

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Speaker 1: depletion zone is enough to prevent current from flowing. So

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Speaker 1: that's why we say diodes are kind of like a

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Speaker 1: check valve. I guess in a way, you can think

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Speaker 1: of it as a check valve in a pipe where

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Speaker 1: you have just put so much water pressure that it

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Speaker 1: breaks the check valve inside the pipe at the pipe itself,

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Speaker 1: possibly might break two and that would be very similar

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Speaker 1: to what we're talking about in circuitry, where a diode

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Speaker 1: has had enough Essentially negative voltage is what it comes

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Speaker 1: down to, because you're you're talking about a reverse bias

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Speaker 1: in this point up to break through that depletion zone. Okay,

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Speaker 1: that's generally what how diodes work, right that they are

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Speaker 1: kind of a one way lane for electricity. But what

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Speaker 1: do we actually use them for. So in some ways

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Speaker 1: we use it exactly as I mentioned, like a way

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Speaker 1: to control the way electricity can flow, but we also

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Speaker 1: use them for other stuff like light emitting diodes. Obviously

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Speaker 1: emit light, they are l e ed s. We use

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Speaker 1: these in everything from light strips to ultra high definition televisions,

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Speaker 1: but we also use diodes to do other things. So

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Speaker 1: one examples, you can use it as a rectifier. So

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Speaker 1: a rectifier is something that allows you to convert alternating

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Speaker 1: current into direct current. So direct current is easy, right,

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Speaker 1: you have current that flows in one direction. This is

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Speaker 1: what batteries do. It goes from the negative terminal into

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Speaker 1: the positive terminal. That's it. It cannot go the other way.

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Speaker 1: It's not going to go from the positive terminal to

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Speaker 1: the negative terminal unless we're talking about conventional current, which

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Speaker 1: we're not. So so it's that's direct current. It's always

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Speaker 1: going to go in that direction, and most of our

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Speaker 1: electronics run on direct current. Alternating current reverses the current

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Speaker 1: direction many times a second. We describe them and hurts.

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Speaker 1: So if it's like a hundred and twenty hurts current,

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Speaker 1: that means a hundred twenty times a second the direction

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Speaker 1: of current is switching, going one way and then the

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Speaker 1: other way. It does this add twenty times a second. Now,

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Speaker 1: getting into why it does this would get into more

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Speaker 1: than what the scope of this episode is about. But

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Speaker 1: this is what we use in order to transmit electricity

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Speaker 1: great distances because alternating current can make use of something

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Speaker 1: called transformers, which are more than meets the eye, but

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Speaker 1: they're not robots in disguise. No transformers are used to

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Speaker 1: change the voltage of alternating current, and stepping up the

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Speaker 1: voltage or increasing the pressure if you will, means you

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Speaker 1: can push the electricity further down power lines and then

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Speaker 1: you would step down the voltage. You would decrease the

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Speaker 1: voltage when you were ready to transmit electricity from the

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Speaker 1: power lines. To say a home or a business. But

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Speaker 1: we still have to be able to change the alternating

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Speaker 1: current into direct current so that our actual electronics can

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Speaker 1: make use of it, and a diode can do that

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Speaker 1: because a diode will only allow current to flow in

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Speaker 1: one direction, So essentially it would only allow a C

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Speaker 1: current to flow through half the time when the direction

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Speaker 1: of the A C current matches the direction the forward

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Speaker 1: direction of the diode. The other half of the time,

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Speaker 1: it would block electricity from from flowing because it's against

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Speaker 1: the diode. Now, this would mean that you would have

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Speaker 1: a pulsing direct current. So you could actually use collections

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Speaker 1: of diodes and some other components to make this a

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Speaker 1: more smooth operation, including enough diode so that whether the

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Speaker 1: electricity is traveling in one direction or the other, the

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Speaker 1: diodes create a pathway that allow the electronics to make

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Speaker 1: use of direct current. It's pretty cool. It's very difficult

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Speaker 1: to describe without the use of visual aids, but yeah,

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Speaker 1: diodes are incredibly important for that. We can also use

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Speaker 1: diodes with radio waves. Again, a deep discussion of radio

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Speaker 1: waves is beyond this, but you know you can encode

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Speaker 1: audio onto radio waves. That's how radios work. If you

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Speaker 1: tune into a radio station, you know the sound has

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Speaker 1: been encoded onto radio waves. We use diodes to extract

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Speaker 1: the audio from the carrier signal of the radio wave.

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Speaker 1: So yeah, they're really important components and I hope you

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Speaker 1: have a greater appreciation of them. And uh yeah, that

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Speaker 1: wraps up this tech stuff tidbits. I'll talk to you

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Speaker 1: again really soon. Y tech stuff is an I Heart

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Speaker 1: Radio production. For more podcasts from my heart ray you

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Speaker 1: visit the I Heart Radio app, Apple Podcasts, or wherever

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Speaker 1: you listen to your favorite shows. H