Speaker 1: Get in touch with technology with text stuff from dot com.
Speaker 1: Hey there, and welcome to text stuff. I'm Jonathan Strickland,
Speaker 1: and today I wanted to address some listener mail and
Speaker 1: and do a full episode based upon a request. This
Speaker 1: comes from Chris via email Now. Chris wrote an incredible email,
Speaker 1: very long, lots of different stuff in it and lots
Speaker 1: of different suggestions, one of which was about the topic
Speaker 1: will be covering today. So here's that section of the email,
Speaker 1: so don't don't be alarmed. I'm going in medias race.
Speaker 1: This is the middle of the email here or really
Speaker 1: the end. Lastly, I was hoping in the future to
Speaker 1: see topics covered like how electronics work, transistors, capacitors, chips, etcetera.
Speaker 1: I worked at radio Shack for five years and got
Speaker 1: really interested in electronic components, but found them pretty confusing.
Speaker 1: That is perfectly understandable. I still have to look up
Speaker 1: the various components and remind myself what each one does
Speaker 1: because I don't tend to work with electronic circuits that frequently,
Speaker 1: and I know in general what needs to happen, but
Speaker 1: sometimes I forget the specifics because there's a lot of
Speaker 1: stuff there, and if you aren't familiar. If you're not
Speaker 1: always working in that world, it can very easily slip
Speaker 1: away from you. And we are talking about lots of
Speaker 1: different components that you measure using different units, And after
Speaker 1: a while you just start to you know, if you again,
Speaker 1: if you're not just naturally inclined to this kind of stuff,
Speaker 1: you start to pull your hair out. Except in my case,
Speaker 1: that's already been done for me, so I just kind
Speaker 1: of rubbed my head. So let's start with the basics.
Speaker 1: And I know this is going to sound incredibly basic,
Speaker 1: but we have to build a foundation before we can
Speaker 1: start talking about the components. So electronics are all about
Speaker 1: leveraging electricity. Not a big surprise, you're you're leveraging electricity
Speaker 1: in order to do something to accomplish something like a
Speaker 1: radio is meant to receive and amplify radio signals and
Speaker 1: and convert them into acoustic signal so that you can
Speaker 1: actually hear them. That that's a simple example. A flashlight
Speaker 1: is meant to channel electricity to end up powering a
Speaker 1: light bulb, which is essentially a resistor. We will talk
Speaker 1: about those that heats up. We're talking about a basic
Speaker 1: incandescent light bulb here, Um and gives off light as
Speaker 1: a result. That's your basic use of that kind of electronics.
Speaker 1: So we're gonna talk about how electronics control electricity. These
Speaker 1: basic components are all used to do that so that
Speaker 1: you can accomplish whatever the goal of your electronic device is. Now,
Speaker 1: most electronic devices have lots and lots of different components
Speaker 1: to them, sometimes worked in various configurations, whether they're in
Speaker 1: series or in parallel. I'm not going to get into
Speaker 1: all all of that because that's beyond what I really
Speaker 1: wanted to focus on in this episode. Instead, in this episode,
Speaker 1: I want to talk about the very basic components and
Speaker 1: what they are intended to do. These are the things
Speaker 1: that make up the circuits that you would see in
Speaker 1: physical circuitry. So if you ever have, uh, you know,
Speaker 1: an old electronic device and you were to take it
Speaker 1: apart and you saw all these little weird do dads
Speaker 1: on a circuit board, I'm gonna tell you what those
Speaker 1: do dads do. Dad. Alright, So first we describe an
Speaker 1: electronics materials is having electrons that fall into certain energy
Speaker 1: bands or electronic bands. Now, the two important ones that
Speaker 1: to talk about are the valence band and the conduction band.
Speaker 1: Electrons and the conduction band are able to move freely
Speaker 1: through the material in question, assuming the conduction band isn't
Speaker 1: totally full. You can think of it kind of like
Speaker 1: a think of it like a nightclub. It's a nightclub
Speaker 1: that's maybe you know, full, so you can still move
Speaker 1: through it freely. Now that nightclubs packed, you're not going anywhere,
Speaker 1: so there has to be you know, almost but not
Speaker 1: quite full for you to be able to move around.
Speaker 1: That's the conduction band. That's the basics of electrical conductivity. UH.
Speaker 1: Whereas the valance band is kind of this um this
Speaker 1: this basic energy level, and there is a gap between
Speaker 1: the valence band and the conduction band. UH. It is
Speaker 1: called the band gap. And depending upon the material, that
Speaker 1: band gap will be of a certain size, and in
Speaker 1: some cases the gap is insurmountable. You cannot get electrons
Speaker 1: from the valence band into the conductance band, and you
Speaker 1: cannot get them to flow, at least not under normal
Speaker 1: operating circumstances. So in that sense, think of you've got
Speaker 1: a like a holding room before you can get into
Speaker 1: the nightclub, and the the doorway going into the nightclub
Speaker 1: has got a big old bouncer and that a goal
Speaker 1: bouncers not letting anyone through. That's your band gap. You
Speaker 1: cannot there's no one even collectively all of you working together,
Speaker 1: you're not gonna be able to budge that bouncer. That
Speaker 1: would be as if you were in a non conducting
Speaker 1: material and I'll get into more of that later. Whereas
Speaker 1: if you're in a room where there's a wide open
Speaker 1: door and you're allowed to go through as long as
Speaker 1: someone else is coming in, that would mean that you
Speaker 1: could flow through properly. You've got you got electrical electrical
Speaker 1: conductivity going on there, and I'll talk more about that
Speaker 1: in a second. I realized this analogy isn't perfect, but
Speaker 1: I'm just trying to simplify things for those who haven't
Speaker 1: really taken this kind of class in physics. So a
Speaker 1: large gap would represent a great deal of energy needed
Speaker 1: to move electrons from the valence band to the conductance band,
Speaker 1: and sometimes that gap is so large as to be
Speaker 1: impossible to cross again under normal operating conditions. So let's
Speaker 1: look at the basic materials that we talk about in electronics, conductors, insulators,
Speaker 1: and semiconductors. Pretty simple to understand. Conductors have high electrical conductivity.
Speaker 1: That means they facilitate the flow of electrons. Uh. They
Speaker 1: have a nearly full but not completely full conduction band.
Speaker 1: Electrons can move freely through this material in response to
Speaker 1: an electric field applied to that material. So you apply
Speaker 1: an electrical field to this material, it will then allow
Speaker 1: electrons to flow through freely. This is the stuff that
Speaker 1: moves electrons from point A to point B. You apply
Speaker 1: a voltage across it, you get electrons to flow. That's current,
Speaker 1: Although technically current flows from positive to negative as opposed
Speaker 1: to the flow of electrons, which is from negative to positive.
Speaker 1: We can thank lots of early UH thinkers for that confusion.
Speaker 1: So current flow and electron flow are in opposite to actions.
Speaker 1: Thank you, Benjamin Franklin. Uh. Alright, So then you've got insulators.
Speaker 1: These do not have electrons within the conduction band or
Speaker 1: they have a full conduction band, so again no room
Speaker 1: for electrons to move around, so there are no free electrons.
Speaker 1: They impede the flow of electrons through that material, and
Speaker 1: most solids fall into this category. Metals are UH an exception,
Speaker 1: but most solids are insulators. So at normal operating parameters,
Speaker 1: you wouldn't be able to apply a strong enough electric
Speaker 1: field to make them conduct electricity. So you could apply
Speaker 1: an electric field to these things, but it wouldn't be
Speaker 1: able to jump that gap between the valence band and
Speaker 1: the conductance band, so it would just stop. You wouldn't
Speaker 1: have any electrical flow through that at all. So we
Speaker 1: use insulators for things like insulation on wires where we
Speaker 1: wrapped the wires in that to help prevent leakage or interference, because,
Speaker 1: as we've talked about many times on this show, the
Speaker 1: flow of electricity is also very closely related to magnetism
Speaker 1: and vice versa. So you have to be able to
Speaker 1: limit interference between different wires if you don't want there
Speaker 1: to be that interaction obviously, otherwise you can end up
Speaker 1: causing shorts, which is when you have an unintended connection
Speaker 1: between two different elements of a circuit and it allows
Speaker 1: electricity to pass from one to the other, almost like
Speaker 1: you think of it like a short cut, you know,
Speaker 1: when we say an electrical short and it means that
Speaker 1: the device itself will not work properly because the electricity
Speaker 1: is not flowing through the pathway you had intended it
Speaker 1: to go in. All right, then we've got semi conductors,
Speaker 1: and we'll talk more about them a little bit later,
Speaker 1: but in general, semi conductors have an almost empty conduction
Speaker 1: band and an almost full valence band, and the band
Speaker 1: gap is relatively narrow. So if you don't apply a
Speaker 1: strong enough electric field at as an insulator, but when
Speaker 1: you apply the right amount of energy and electric field,
Speaker 1: it will allow electrons jump from the valance band to
Speaker 1: the conductor band and move freely within the material. You
Speaker 1: do this by doping the material, which is when you
Speaker 1: insert impurities into the semiconductor on purpose. Doping a semiconductor,
Speaker 1: which is all about introducing impurities specifically at at predetermined levels,
Speaker 1: will determine the energy levels required to do this, and
Speaker 1: that's the basis for slid state electronics. We'll get into
Speaker 1: more about semiconductors towards the end of this. And we
Speaker 1: also have to remember voltage and current, something that I
Speaker 1: always have trouble remembering. So voltage is a lot like
Speaker 1: water pressure, all right. That's that's the the amount of
Speaker 1: electrical pressure being applied, and the higher the voltage, the
Speaker 1: more electrons want to move from the concentration of electrons
Speaker 1: to the or positive side. Now, the actual flow of
Speaker 1: electricity is the current, so they are related but not
Speaker 1: the same thing. So voltage and current, and then you
Speaker 1: multiply those two dependent together and you get the power.
Speaker 1: So voltage times current equals power. Alright, So those are
Speaker 1: your basics. Now we're gonna go through and talk about
Speaker 1: the very individual components and what they do. So first
Speaker 1: we have resistors. Resistor does pretty much what it sounds
Speaker 1: like it does. It resists but does not halt the
Speaker 1: flow of electricity. I'm gonna talk a lot about electricity
Speaker 1: in terms of water because it is a useful analogy,
Speaker 1: and it's also very common to talk about the similarities
Speaker 1: between electricity flowing and water flowing when you're discussing these components.
Speaker 1: So let's say that you have two different pipes. You've
Speaker 1: got a brand spanking new pipe. It's shiny and beautiful
Speaker 1: and free from any any irregularities, and it allows water
Speaker 1: to flow through with a minimum of resistance. That water
Speaker 1: is just flowing right through easily. You've got a second, old,
Speaker 1: gnarly pipe, and this one's got calcium build up in it.
Speaker 1: They're all these bumps and stuff on the inside. So
Speaker 1: water actually encounters resistance friction, if you will, as it's
Speaker 1: flowing through, and it does not flow through as easily.
Speaker 1: Resistors are like that old gnarly pipe, and they are
Speaker 1: invented on purpose for specific reasons. So why would you
Speaker 1: want to have an electronic component that actually slows down
Speaker 1: or impedes the flow of electricity for some reason. Well,
Speaker 1: sometimes you have to limit the amount of electricity that
Speaker 1: can flow through part of a circuit within a given
Speaker 1: amount of time, sort of like how a faucet going
Speaker 1: back to water, how fauce it can limit how much
Speaker 1: water can flow through your water pipes into your sink.
Speaker 1: So you wouldn't want just an on off switch for
Speaker 1: the water coming into your home. That water is at
Speaker 1: a much higher pressure, you know, it's it's a higher
Speaker 1: pressure to deliver the water to your house. And if
Speaker 1: all you had wasn't on off switch and you flipped it,
Speaker 1: you would have water blasting through the pipe according to
Speaker 1: the amount of pressure that was built up behind it.
Speaker 1: That'd be a little bit nerving, especially if you just
Speaker 1: wanted to have a nice frosty glass water. So you
Speaker 1: want to have some sort of limiter on that to
Speaker 1: control the amount of water that's or the pressure of
Speaker 1: the water that's coming in. So resistors reduced the amount
Speaker 1: of voltage placed on other electronic components within a circuit
Speaker 1: by restricting the amount of current that can flow through
Speaker 1: the resistor. The reason why this is important is that
Speaker 1: we cannot create a battery for every single type of
Speaker 1: electronic device that's out there. It's not practical. So batteries,
Speaker 1: different batteries, Different types of batteries have different voltages. So
Speaker 1: you could, in theory, develop a battery specifically for a
Speaker 1: particular type of electronic device that would not require resistors
Speaker 1: because the battery is providing exactly the voltage needed for
Speaker 1: whatever electronic components are in net. But it's not practical
Speaker 1: to do that for everything. We want standardized batteries, and
Speaker 1: then we use things like resistors to help control the
Speaker 1: voltage in those electronic components so that the right amount
Speaker 1: of voltage is applied to those specific parts of the
Speaker 1: electronic circuit, rather than having to have a billion different
Speaker 1: types of batteries. That would not be practical. So there
Speaker 1: are many different types of resistors designed to work on
Speaker 1: specific amounts of electrical power. Now, some have changeable resistor
Speaker 1: values dependent upon the amount of voltage placed across them.
Speaker 1: They're called nonlinear or voltage dependent resistors. Resistor values can
Speaker 1: also change when the temperature of the resistor changes UH.
Speaker 1: Different types of resistors do this. Some can also be
Speaker 1: mechanically adjusted. So it all depends upon what you need
Speaker 1: the resistor for and why what you needed to do.
Speaker 1: That's what would determine which type of resistor you would use.
Speaker 1: The unit of measurement for a resistor is the ohm
Speaker 1: oh h M. Resistor values are ten percent apart from
Speaker 1: each other, and resistors are color coded with bands of
Speaker 1: color or rings of color. So the first ring represents
Speaker 1: the first digit of the resistors value. So what you
Speaker 1: would do is you would look at the first ring,
Speaker 1: whatever color it was, you would cross reference that with
Speaker 1: the with a color UH index, and it would tell
Speaker 1: you what the value of the resistor is for the
Speaker 1: first digit. The second ring tells you the value of
Speaker 1: the second digit. So then you've got the two UH
Speaker 1: the two digits that are involved. The third tells you
Speaker 1: the power of ten to multiply by, so it might
Speaker 1: be ten thousand, and then you would multiply. Let's say
Speaker 1: that your first two digits are a twenty two and
Speaker 1: a seven, and you would multiply that by ten thousand.
Speaker 1: You have twenty seven thousand poems there, and the fourth
Speaker 1: ring would tell you the tolerance of the resistor plus
Speaker 1: or minus whatever percentage. Uh So, the physical size of
Speaker 1: the resistor and the amount of power it can handle
Speaker 1: tends to be proportional. So in other words, the larger
Speaker 1: the resistor, the more power it can handle. In general.
Speaker 1: So those are resistors covers that basic component. Now let's
Speaker 1: move on to capacitors. Alright. So capacitors are similar to
Speaker 1: batteries and that it's a means of storing electrical energy,
Speaker 1: but unlike batteries, instead of creating an a uh, electrical
Speaker 1: flow through a chemical reaction that is steady the entire
Speaker 1: time it is designed to release a it's it's entire
Speaker 1: stored electrical charge all at once. So let's say they've
Speaker 1: got two leads of a capacitor. You have a difference
Speaker 1: in voltage across these two leads. That's when a capacitor
Speaker 1: is charged. So one lead has a greater build up
Speaker 1: of electrons than the other lead does. Uh. Now, if
Speaker 1: you were to connect the leads together, you would short them.
Speaker 1: You would have a discharge of that capacitor and the
Speaker 1: voltage would equalize across the two, so you get a
Speaker 1: release of a quick burst of electricity. So capacitors can
Speaker 1: pass alternating current freely. A C current will just pass
Speaker 1: through a capacitor as if it were not really there.
Speaker 1: Direct current, however, will charge a capacitor. It will have
Speaker 1: that build up of electrons on one side, while the
Speaker 1: other side doesn't get that build up of electrons, and
Speaker 1: then you have that difference in voltage. Alternating current just
Speaker 1: will pass back and forth through it without any problems.
Speaker 1: So capacitors contain the same fundamental parts. You have at
Speaker 1: least two conductive plates separated by a non conductive material.
Speaker 1: That's the dilector. The amount of charge held by capacitor
Speaker 1: is measured in units called faret's. But a faret is
Speaker 1: a large amount of capacitance, so large that you don't
Speaker 1: really ever talk about a ferret. Instead we end up
Speaker 1: talking about micro farets, which are about a well, which
Speaker 1: are one million of a ferret, so much smaller. Faret,
Speaker 1: by the way, not ferret, two different things. Nice Mormot
Speaker 1: capacitance is dependent upon surface area, so it's directly proportional
Speaker 1: to the surface area of those leads. Those those capacity plates. Um.
Speaker 1: It is indirectly proportional to the distance between the plates.
Speaker 1: So the greater the distance between the plates, the lower
Speaker 1: the capacitance. Uh. It's also uh dependent upon the dielectric
Speaker 1: constant of the insulating material. And they are used for
Speaker 1: things that need a quick release of electricity rather than
Speaker 1: a steady flow. So, for example, a tradition all flash
Speaker 1: on a camera. So you've got an old camera and
Speaker 1: you've got the the the flash, Uh, you know it
Speaker 1: bursts in this quick burst of light. Well, it needs
Speaker 1: that quick It needs access to a quick burst of
Speaker 1: electricity in order to do that, and that's what capacitors
Speaker 1: are good for. And it takes some time for the
Speaker 1: capacitors to build up the charge again so it can
Speaker 1: do it another time. That's sort of you know, if
Speaker 1: you're using the old ones, you hear that noise. It's
Speaker 1: the the discharge and then charging of the capacitors that
Speaker 1: require you to take a moment between taking pictures with
Speaker 1: those old style camera flashes. Now obviously newer ones used
Speaker 1: different a different approach, but you often have capacitors that
Speaker 1: actually provide the electricity for those. Now, the voltage of
Speaker 1: a capacitor cannot change instantly, it's important to remember, and
Speaker 1: quick voltage changes in a capacitor produced large current changes.
Speaker 1: Capacitor store energy in an electric field. Now, the reason
Speaker 1: I mentioned all that is because we're now going to
Speaker 1: talk about inductors, and inductors are kind of, um the
Speaker 1: opposite of capacitors, or really maybe not even opposite is
Speaker 1: the right way of saying it. In many ways that
Speaker 1: they behave in opposite ways than capacitors do, but we'll
Speaker 1: get to that. So basically, an inductor at its most
Speaker 1: basic level is a coil of wires, so sometimes we
Speaker 1: just call them coils and not inductors. Uh. They deal
Speaker 1: with what is the electrical equivalent of momentum. So if
Speaker 1: you're familiar with momentum, essentially this is that idea that
Speaker 1: you get a you know, objects in motion tend to
Speaker 1: stay in motion. So let's say you've got a large
Speaker 1: mass moving at a particular velocity. It has a certain
Speaker 1: amount of momentum, and you have to overcome that momentum
Speaker 1: to slow down and stop that uh, that that mass.
Speaker 1: So it's the same type of thing with inductors, except
Speaker 1: we're talking about the electrical equivalent of momentum. We're talking
Speaker 1: about the flow of electricity. So again going back to
Speaker 1: the water analogy, Let's say that you've got a water hose,
Speaker 1: a really long one, several hundred feet long, and you've
Speaker 1: coiled it up so it's in a nice long coil
Speaker 1: and it's filled with water. There are gallons of water
Speaker 1: inside this hose, and the end of the hose is
Speaker 1: tilted at such an angle so the water is not
Speaker 1: just flowing right out. You put a plunger into the
Speaker 1: other end and you start to press on the plunger
Speaker 1: to push the water out. Now, all of that water
Speaker 1: is not just going to simultaneously start to move together.
Speaker 1: It actually is going to take some time for the
Speaker 1: pressure you are applying to exert enough force to push
Speaker 1: the water out to overcome the inertia within that coil
Speaker 1: of water hose. And once you get that water coming
Speaker 1: out at the speed at which it can come out
Speaker 1: and you let go of the plunger, the plunger is
Speaker 1: going to continue going down that tube because of inertia.
Speaker 1: That's the same sort of thing with inductors, except instead
Speaker 1: of water, we're talking about electricity. So coils of wire
Speaker 1: will pass d C current but will block a C current.
Speaker 1: So in other words, direct current can flow through an inductor,
Speaker 1: but alternating current would be blocked because it cannot flow
Speaker 1: the opposite way through the coil. So that makes it
Speaker 1: the opposite of capacitors. Remember, capacitors would pass alternating current
Speaker 1: that can flow straight through, but would block direct current.
Speaker 1: Direct current would charge a capacitor a capacitor, but could
Speaker 1: not just flow through the capacitor. In this case, direct
Speaker 1: current can flow through an inductor, but a c alternating
Speaker 1: current would be blocked. The standard unit of inductance is
Speaker 1: the henry. I wish I could tell you why, but
Speaker 1: I honestly don't know. I'm sure some of you out there,
Speaker 1: you electricians, are very familiar with the reason why and
Speaker 1: could tell me and feel free to I I honestly
Speaker 1: do not off hand. No, the inductance of a coil
Speaker 1: is indirectly proportional to the length of the coil, but
Speaker 1: directly proportional to the cross sectional area of the wire, So,
Speaker 1: in other words, the gauge of the wire is important here.
Speaker 1: It's also proportional to the square of the number of
Speaker 1: turns in the coil, and it's directly proportional to the
Speaker 1: permeability of the core material. Now the core is whatever
Speaker 1: this coil is wrapped around. Now it could be wrapped
Speaker 1: around air, or it could be wrapped around something like iron,
Speaker 1: which is incredibly effective. So those are that's what we're
Speaker 1: talking about with the cords, whatever the wire or is
Speaker 1: coiled around. So when current first starts flowing into the coil,
Speaker 1: the coil wants to build up a magnetic field. We've
Speaker 1: talked about this again and again that you start running
Speaker 1: electricity through a coil of wire that's coiled around like
Speaker 1: an iron core, like a nail, and you start to
Speaker 1: you create an electro magnet. Well, once that field is built.
Speaker 1: While while the magnetic field is building, the coil inhibits
Speaker 1: the flow of current through the wire. But once the
Speaker 1: field is built, current can flow normally through the wire.
Speaker 1: So if you were to have an inductor hooked up
Speaker 1: to a light bulb, let's say and you flip a
Speaker 1: switch so that you know, technically in an electronics would
Speaker 1: say that you close the switch, so you have created
Speaker 1: a closed path so electrons can flow through. The electrons
Speaker 1: would flow through the inductor, which would start to build
Speaker 1: up a magnetic field. So at first you would get
Speaker 1: the light bulb coming on, then it would start to
Speaker 1: dim a bit because as that magnetic field is getting
Speaker 1: built up the lightbulb, you know, the electricity would be
Speaker 1: limited to the light bulb. It would actually act as
Speaker 1: sort of resistor, and the light bulb would start to
Speaker 1: get dimmer. But then eventually then that magnetic field would
Speaker 1: get charged up as much as it can because it's
Speaker 1: direct current, not alternating current, and you would reach a
Speaker 1: level where it was stabilized. Current would flow fine. At
Speaker 1: that point, you can actually turn off the switch, you
Speaker 1: can open it. In other words, the magnetic field around
Speaker 1: the coil would keep current flowing through the coil until
Speaker 1: that magnetic field collapsed. So even though you turn the
Speaker 1: switch to off, because you have an inductor, that lightbulb
Speaker 1: would stay lit until the magnetic field and the inductor collapsed,
Speaker 1: in which case it would stop inducing current to flow
Speaker 1: through and the light bulb would go off. So the
Speaker 1: experience you would have is turn the switch on, light
Speaker 1: bulb comes on, light bulb starts to get dim, light
Speaker 1: bulb gets bright again, You turn the switch off, lightbulb
Speaker 1: stays lit for a while, and then turns off. That's
Speaker 1: what it would look like to you, So pretty interesting
Speaker 1: to me. Now. So, an inductor stores energy in its
Speaker 1: magnetic field, and it tends to resist any change in
Speaker 1: the amount of current flowing through it, thus making it
Speaker 1: different from capacitors. Because capacitors store things an electric field,
Speaker 1: inductor store things energy, not just things. Capacitor store energy
Speaker 1: and electric fields, and inductor store energy and magnetic fields.
Speaker 1: And capacitors resist changes to voltage, whereas inductors resist changes
Speaker 1: to current. So really interesting about that. So because of
Speaker 1: this relationship between inductors and capacitors, these two different components
Speaker 1: are sometimes referred together as dual components because they they
Speaker 1: are opposites that complement one another. The current in an
Speaker 1: inductor cannot change instantly the quick current changes produced the
Speaker 1: large voltage, and inductors store their energy in those magnetic fields.
Speaker 1: That's what sets them opposite of capacitors, because they are
Speaker 1: all the opposite of those things. And you might wonder
Speaker 1: what are inductors used for. I mean, that lightbulb example
Speaker 1: seems kind of crazy. Well, they're used for lots of stuff.
Speaker 1: For example, if you've ever gone to uh, like traffic
Speaker 1: lights that are that respond to the presence of vehicles.
Speaker 1: Most of those are using inductors. So underneath the pavement
Speaker 1: where you're driving on top of you know, there are
Speaker 1: giant coils of wire, and when you stop your car
Speaker 1: at a stoplight that has one of these systems, your
Speaker 1: car starts to act as the core for that inductor loop.
Speaker 1: You've got this massive amount of steel that's right there
Speaker 1: that affects the inductance of the that cable. You have
Speaker 1: a meter attached to the cable that measures the inductance.
Speaker 1: So when it measures a change in inductance, that meter
Speaker 1: knows there's a vehicle at that location and sends that
Speaker 1: information to the control unit for the traffic system and
Speaker 1: thus changes the traffic cycle so that you get a
Speaker 1: green light faster. So if you're ever at one of
Speaker 1: those intersections where the the light cycles depend heavily upon
Speaker 1: whether or not there are cars present at the intersection,
Speaker 1: that's generally speaking, what is happening. You've got these inductors.
Speaker 1: The inductance changes, sends the message to the meter, or
Speaker 1: rather the meter detects the inductor the change in inductance
Speaker 1: and then sends that onto the traffic control system that
Speaker 1: will then, at least in theory, get you on your
Speaker 1: way a little faster. So that's inductors. Now let's take
Speaker 1: a look at transformers, which are more than meets the eye.
Speaker 1: So I'm not talking about autobots in Decepticons, as much
Speaker 1: as I would love to do that, instead of talking
Speaker 1: about the basic electronic component. So let's say you've got
Speaker 1: a single core, like like that iron nail. Let's say
Speaker 1: and you put multiple coils of wire over this same
Speaker 1: iron core, and then you force a DC current through
Speaker 1: one of those coils of wire, not all of them,
Speaker 1: just one. Now, as that current charges, it will induce
Speaker 1: current to flow through the other coils wrapped around that
Speaker 1: same core, and constantly changing the voltage of that primary coil.
Speaker 1: The one that you've got attached to some sort of
Speaker 1: voltage generator will cause currents that change in a similar
Speaker 1: fashion in the other coils. Now, if the other coils
Speaker 1: have more loops than the primary coil, the voltage will
Speaker 1: be greater, but the current will be lower. I'll explain
Speaker 1: that in the second. So let's say we've got we'll
Speaker 1: make it really simple. We'll just do two coils. Let's
Speaker 1: say we've got an iron core and we've got a
Speaker 1: primary wire coiled around it ten times, and we have
Speaker 1: a second wire coiled in the same direction around that
Speaker 1: iron core, but it is coiled twenty times, and we
Speaker 1: apply a varying voltage across the primary wire. The voltage
Speaker 1: across the second wire will be twice as much because
Speaker 1: there are twice as many coils, but the current will
Speaker 1: be as much as that in the primary coil. And
Speaker 1: that's because you have to conserve power. You cannot create
Speaker 1: or destroy power. You have to conserve it. And power,
Speaker 1: like I said earlier, is equal to voltage times current.
Speaker 1: So if we double the voltage, but ultimately the power
Speaker 1: in the secondary coil has to be the same as
Speaker 1: the primary coil. The only way to address that is
Speaker 1: to have the current. So that's you know, that's what happens.
Speaker 1: So if the second coil is coiled in the same
Speaker 1: direction as the primary, like I was saying before, the
Speaker 1: voltage is in the same polarity as that of the
Speaker 1: generator the primary coil. If the second coil is coiled
Speaker 1: in the opposite direction of the primary coil, then the
Speaker 1: voltage is in the opposite polarity from the primary coil.
Speaker 1: Polarity is really important but also pretty complicated, So I'll
Speaker 1: probably spend another episode to explain that concept because it's
Speaker 1: really a bit much to go into right now. But anyway,
Speaker 1: this is the basics for power transmission using alternating current.
Speaker 1: It's the reason why we have alternating current distributing our
Speaker 1: power instead of direct current. So, and that old Tesla
Speaker 1: versus Edison argument, really i should say Westinghouse versus Edison argument,
Speaker 1: where Edison was saying direct current was best and Westinghouse
Speaker 1: was saying no alternating current was best. The things that
Speaker 1: let alternating current win out over direct current, or that
Speaker 1: using transformers you could boost the voltage to huge high
Speaker 1: voltage numbers, which were great for power transmission. You could
Speaker 1: transmit over vast distances using high voltage wires, and then
Speaker 1: you would use other transformers on the opposite end to
Speaker 1: step down the voltage until you reach the level that
Speaker 1: was safe for homes, which in the United States is
Speaker 1: two forty volts. Uh. Now, keep in mind that when
Speaker 1: you're talking about transmiss voltages, it could be anywhere between
Speaker 1: a hundred fifty five thousand to seven sixty thousand volts.
Speaker 1: So we're talking huge differences here, and it's all because
Speaker 1: you could use this basic element of electronics with these
Speaker 1: transformers to step up or step down the voltage simply
Speaker 1: by using different coils along a core, So that was
Speaker 1: incredibly useful. You could end up transmitting power over great distances.
Speaker 1: Direct current, however, is very different. It is most efficient
Speaker 1: if it is close to whatever the load is on
Speaker 1: the line. So the load is whatever the electricity is
Speaker 1: meant to power. So in the case of homes, you
Speaker 1: would want the power plant to be relatively close to
Speaker 1: the homes that are receiving electricity. If you were using
Speaker 1: direct current, um this is you know, it would be
Speaker 1: incredibly useful to have direct current powering our homes because
Speaker 1: most of the stuff we have relies on direct current.
Speaker 1: It actually has to convert the alternating current that comes
Speaker 1: to the house into direct current. You have these converters
Speaker 1: that are part of the electronics that allow it to
Speaker 1: do that. If you had direct current being uh supplied
Speaker 1: directly to your house, you wouldn't need the conversion part
Speaker 1: of those devices. However, you wouldn't be able to transmit
Speaker 1: it over great distances like you can with alternating current.
Speaker 1: So in case you're wondering about the power grades in
Speaker 1: the United States, we I mentioned that you have those
Speaker 1: those high voltage lines that are carrying between a HUDD
Speaker 1: to s hred sixty thousand volts. When you get to
Speaker 1: distribution levels, you step down that voltage to less than
Speaker 1: ten thousand volts typically, and then you get to distribution
Speaker 1: buses that have transformers that reduce it further to seven thousand,
Speaker 1: two hundred volts or less. And then you have the
Speaker 1: homes that are connected to a final transformer that step
Speaker 1: it down again to the voltage of two volts or so.
Speaker 1: So incredibly useful and here at how stuff works. Recently,
Speaker 1: as of the recording of this podcast, we had a
Speaker 1: lovely transformer fire right next to the building we work in,
Speaker 1: which cut power to our part of the building for
Speaker 1: some time. So if you've ever been near a transformer
Speaker 1: when it's blown, it's a pretty spectacular thing. It's usually
Speaker 1: lots of sparks in a really loud bang, and often
Speaker 1: requires the work of dedicated personnel to repair. And it
Speaker 1: does also typically mean that you have a loss of
Speaker 1: power for at least a localized area. Pretty impressive when
Speaker 1: it happens. Luckily, it doesn't happen all that frequently. The
Speaker 1: electrical storms and areas of or times of great use
Speaker 1: can make them more vulnerable. Now let's move on to
Speaker 1: semiconductors and how they are used in electronics. So we've
Speaker 1: got lots of different uses for semiconductors. I'm going to
Speaker 1: talk about two specific ones. There are iodes. Diodes are
Speaker 1: really useful. They allow current to flow in only one direction,
Speaker 1: so it's like a one way channel or a valve.
Speaker 1: So electricity flowing one way is fine, but it cannot
Speaker 1: flow back the other way, and semiconductor doping allows for
Speaker 1: this to happen. Remember I mentioned earlier. Doping is when
Speaker 1: you have introduced impurities into the semiconductor material to give
Speaker 1: it specific UH features. So there are two different types
Speaker 1: that we're going to talk about. There's end type layers
Speaker 1: of semiconductors, so you can think of that as an
Speaker 1: excess of electrons. It has lots of negative electrons that
Speaker 1: are just ready to flow out of there. And then
Speaker 1: you have P type layers and these have electron holes
Speaker 1: or at least you know, in other words, of the
Speaker 1: capacity to take on electrons. So if you pair this together,
Speaker 1: you get what's called a P N diode, which only
Speaker 1: allows electricity to flow in one direction. It can Electrons
Speaker 1: can come through UH and flow to the holes, but
Speaker 1: they can't go the other way, so very useful and
Speaker 1: electronic components where you need to direct the flow of
Speaker 1: electricity along a particular path and prevent it from coming
Speaker 1: back through that pathway. Transistors are another type of semiconductor
Speaker 1: that use a small amount of current to control a
Speaker 1: large amount of current. So while a diode is p n,
Speaker 1: transistors are either p n P or n p n,
Speaker 1: and if you apply an electrical current to the center layer,
Speaker 1: which is also known as the base, electrons will move
Speaker 1: from the N type side to the P type side,
Speaker 1: and that initial small current allows for much larger current
Speaker 1: to flow through the material at that point. So transistors
Speaker 1: act as switches or amplifiers incredibly useful. So when we
Speaker 1: talk about transistors in solid state electronics, these are the
Speaker 1: things that allow us to build logic circuits. And it's
Speaker 1: because we can allow electrons to either flow or prevent
Speaker 1: them from flowing. It's also why things like electron tunneling
Speaker 1: can be such a problem. Electron tunneling is a quantum effect,
Speaker 1: so you can think of an electron as not really
Speaker 1: existing in a specific point in space at any given time,
Speaker 1: but rather having the potential to exist in an area
Speaker 1: of space at any point in time. So think of
Speaker 1: it like a cloud where an electron could be, and
Speaker 1: that cloud covers all the potential places the electron could be,
Speaker 1: and there's different probability for different parts of the cloud.
Speaker 1: If your transistor gates are so small, so narrow, so thin,
Speaker 1: I guess I should say not narrow, that the cloud
Speaker 1: of potential can overlap the transistor gate. That means there
Speaker 1: is the possibility that at some point the electron could
Speaker 1: exist on the other side of the transistor gate, even
Speaker 1: if the gate never opened. And if there's a possibility,
Speaker 1: that means sometimes it does appear on the other side
Speaker 1: of the gate. We call it electron tunneling. It's not
Speaker 1: really tunneling. It's just if there is the possibility that
Speaker 1: could be on the other side, sometimes it is on
Speaker 1: the other side, which means that you cannot actually control
Speaker 1: the flow of electrons. In that case, it would mean
Speaker 1: that your transistors would be ineffective in doing what they're
Speaker 1: supposed to do. They wouldn't really be able to act
Speaker 1: to switches reliably, and you would get errors in your computations.
Speaker 1: It might work most of the time and then only
Speaker 1: some of the time not work. But even then that's problematic,
Speaker 1: which is one of the engineering challenges that transistor designers
Speaker 1: and multi or rather microprocessor designers encounter all the time,
Speaker 1: you know, finding new materials that are better at acting
Speaker 1: as transistors switches, it's a big part of it. And
Speaker 1: coming up with different architectures to really take advantage of
Speaker 1: electron flow is another big part of it, alright. So
Speaker 1: those are the basics, the basic electronic components that you
Speaker 1: can talk about with, you know, if you're looking at
Speaker 1: it from a very high level. Obviously there's tons of
Speaker 1: other stuff that I didn't get into, and some of
Speaker 1: it just requires you to pair up or otherwise put
Speaker 1: into series or parallels some of the components I've mentioned
Speaker 1: to to get whatever effects you want. But those are
Speaker 1: the basics, so when you look at those different components,
Speaker 1: you can remember that this is all about making sure
Speaker 1: that the electrons are behaving in the way that makes
Speaker 1: whatever it is you intend to do possible. I want
Speaker 1: to thank Chris for sending that email in and asking
Speaker 1: about this, because it was fun to cover this this
Speaker 1: this topic again and to really kind of dive in
Speaker 1: more deeply than I had before, and I want to
Speaker 1: encourage you guys to write in and ask about other topics.
Speaker 1: Whether it's a technology or a company or a person,
Speaker 1: or maybe it's someone that you want to have on
Speaker 1: the show, either as a guest host or someone for
Speaker 1: me to interview. Any of that is fine. Please let
Speaker 1: me know, or just feedback in general about the show.
Speaker 1: I would love to hear more from you guys. Sent
Speaker 1: me a message. The email address is tech Stuff at
Speaker 1: how stuff works dot com, or drop me a line
Speaker 1: on Facebook, Twitter, or Tumblr. The handle it all three
Speaker 1: is tech Stuff H s W. And I'll talk to
Speaker 1: you again really soon. For more on this and thousands
Speaker 1: of other topics. Works dot com