Overview of Transistors, Diodes, Capacitors - Circuit Theory Explained!

the next electric circuit component that's got so many uses is one that I know that every one of you that's watching this has heard of and it's called the transistor right so transistor lots of people have heard of transistors but not many people unless you study this stuff really know what they do I mean you know transistors are in radios you know transistors are in cameras you know transistors are definitely in computers and on computer chips right you've heard of those transistors millions of transistors on the computer chip you know that they're in memory sticks you know they're everywhere and truthfully most of the technology of of the last 50 years is a direct result of Having learned how to build these things we call transistors so they're so incredibly important it's hard to overstate their importance to be honest with you what does a transistor do big big big picture it can do two main things the first thing it can do is it can act as sort of like an electronic switch normally a switch and a wall socket or something can be open and I can open the circuit and you can close the switch and that will let the circuit function a transistor can also function as a switch but there's nothing physically moving inside it's just how it's built and I'll show you in a second sort of how it works but it can act as a switch that's the number one use for it and that's mostly how it's used inside of a computer and and all the things that a computer can do arise because of the behavior of transistors a transistor a second function right is that it can act as an amplifier so literally that is when you turn the volume knob on your stereo system you're basically manipulating those transistors in there to push out more current so a transistor can take a teeny tiny input signal like your voice right maybe coming in on a wire and it can make a direct replica of it on the output but much bigger much higher am much higher volume level for lack of a better word and that goes into your speakers so when you adjust your volume you get a nice rich beautiful loud sound that's a direct result of a transistor right so two functions of a transistor switch and amplifier now what how do you spell this thing it's called a trans istor all right now there's actually lots of different ways to draw transistors actually there's lots of different types of transistors and we're not going to get into the types right now but the basic way you draw a transistor is like this it has three terminals so here's the first wire here's sort of like the second wire that kind of comes in at an angle it's just the way it's drawn and the third one goes out at an angle and you have a little arrow here now depending on the exact type of transistor you have the arrow might be in a different orientation and actually this little symbol here with the the angle coming in and coming out May look slightly different but by and large this is the basic symbol for for a transistor it has three terminals you have this terminal here a terminal coming out here and you have a terminal going out so if you look at a real transistor you know that we'll show you here in just a second you'll have three wires basically going into the thing all right now I'm not going to get into transistor Theory here but basically what I was saying a minute ago if you're sending your voice in over a wire let's say you may have a very small voltage signal coming in on that wire right and the way you send the input the input comes into this leg right here the output has current flowing down through the thing like this this is sort of the output like this if you stick a volt meter here you might see something that looks like this much larger but it's a direct replica of the input and that's how it behaves as an amplifier so I might send a small signal and a voice signal or any other signal over this guy and and you have to obviously design the circuit around the transistors there's many many ways to do it the basically the input gets replicated at the output but just much bigger so you're sending more current more power to that whatever you're doing I'm thinking in terms of voice amplifiers but there's amplifiers and all sorts of electronics that don't have anything to do with the voice you may need to make some signal larger or even make it smaller and transistors can do that that's that's the main function of it in terms of an amplifier now if you think about it in a digital system right in a digital system you have an on or and off a one or zero right so you won't have this nice wave but you might have a on going straight up and off going back to zero and when you push this through the output is going to be on or off so when I send an on Signal here I'm going to get an on Signal coming out when I send an off signal like a zero volt signal here I might get an off signal coming out so this part of the circuit here does not function nothing happens here unless I actually turn the on signal on coming in here if I take this away no current flows here if I send a voltage in here then this part of the circuit turns on so that's how it behaves as a switch it's directly a result of how the thing works it's like if you send the signal in here then a signal comes out the other end so I can isolate certain parts of the circuit like maybe maybe I have an entire thing going on over here a fan a motor maybe I have 50 more transistors here maybe I've got something crazy over here but I've isolated it through this transistor this guy's not even functioning unless I turned it on by sending a signal in here right so that's how it behaves as a switch now if you take four or five million transistors and build a computer chip that are basically arranged to allow these transistors to be interconnected in ways that are beyond the scope of this discussion but basically they're interconnected like that then you can do lots of great things with transistors you can create machines that add numbers together which is basically what a computer does and if you create millions and millions of transistors in there then you can do lots of calculations very very very quickly because these transistors and this is really an important part they turn on and off extremely fast much faster than a mechanical switch could ever do so transistors can amplify signal and they can also act as sort of a discrete switch switching things on and off at extremely fast speeds and that's really why they're so useful computers because they can operate really fast so these computer speeds that are going higher and higher every year is a direct result of pushing these things faster and faster and putting more of them on the chips and as you study Electronics more and more and more you'll learn how to connect these transistors together to do things like build memory chips build computer chips and so on all right one final guy I want to talk about is something that everybody's heard of it's called a trans former now I'm not talking about the giant robots that you see in the movies I'm talking about the Transformers that you might see up on the on the polls right on the side of the road those big cans right those are usually Transformers basically a Transformer is allows a voltage to be increased or decreased to another voltage inside of a circuit specifically they work with those AC signals the ones that go up and down we talked about HC in the last section so the the symbol for a transistor might look like this maybe you've got a coil of wire here you've usually got something in the middle you can usually denote it by some lines this is like an iron core and then over here you might have maybe less coils that's why I haven't drawn this way maybe fewer coils or maybe have more coils depends on what you're trying to do but if you send an AC signal in here which is a signal that goes up and down right then what's going to happen is and these things are wound I should say there's a core here like a usually it's an iron core or something and this coil of wire is coiled around it and the other coil is also cooled around of course the wires are not touching they're all insulated so they're not touching but they're wound around a common core so what happens basically is when you send the AC signal through here you get a magnetic field that is flip-flopping back and forth because it's oscillating back and forth and this magnetic field interacts with the second coil and generates a voltage in the second coil and you can increase or decrease that voltage depending on how many turns you have on this coil so basically if I have a wall socket that's 120 volts let's say and I'm building something but my circuit that I'm building only needs maybe 10 volts ac 10 volts let's say then I'm going to need to change that voltage from 120 volts down to 10 volts or whatever I'm trying to use I'm going to have to I can't hook it up directly I'll blow my circuit up I need to step it down so I might create a situation with a Transformer where I will go in and basically have the current go into one side of this coil and an output on the other side the output would be over here might be a different voltage than what I'm putting in So that's its main FOC focus and its main use is to step up or step down the voltages and that's why you see them on the side of the road on the tell on the I say telephone poles on the poles on the side of the road because they're taking that high voltage coming in from the power plant and they're changing it to a lower voltage to come into your house so that's that's what that guy's used for so if you wanted to see a picture of that here's a picture of a transformer and basically you can't see that much but inside of there is a some kind of a metal core and coming in one side you've got a winding and coming on the other side you get a winding and you hook it up in your circuit and there you go so you have to design your Transformer there's a lot of design that goes into it to get the exact function that you're basically seeking now here is a picture of a transistor there are really not much to look at they certainly don't look like what the picture I've drawn on the board is but you can see that it's a device that has sort of like a black component at the top and there's three legs to it and the details of how you identify these legs will come as you study these things later but basically one of the legs is the input so to speak and then the other two are the ones that are on the other side of the device that basically are in the output so depending on what you're trying to do you'll hook it up different ways to be able to turn on the transistor and to send the output to wherever it is you need it to go in the circuit so I hope you've enjoyed this overview of basic circuit components this is not an exhaustive list of circuit components there are actually more of them but they're not used as much and they're used in situations that you know you'll need them when you need them but they're not something that that's in your back pocket every day for everyday uses so this is not an exhaustive list but it's a very good start if you understand the basics of these things then I hope you can see how amazing circuits can be created to do various uses so basically you have the sources which are the voltages you always have a plus minus either printed on there or implied in the diagram you have unit of volts you have resistors which resist all current flow to various levels depending on the value in ohms it has the kind of the jagged line like this capacitor is the unit of the farad you commonly see microfarads or even nanofarads and they're not physically connected here because the charge is allowed to pile up in there and store energy in the form of an electric field the inductor is simply a coil of wire in many cases with some piece of metal inserted inside of the coil the purpose of this guy is to store energy in a magnetic field is sort of the exact dual of the capacitor above it we talked about when you might use that the unit is the Henry but of course you might see micro Henry or Millie Henry's or whatever it is you have depending on what you've designed we have a diode it allows current to flow Only One Direction if you flip the current direction around try to hook it up backwards nothing's going to happen no current is going to flow then we have the light emitting diode which is exactly the same thing but also emits light of whatever color you've designed whenever electric current flows through there then we have a transistor which is basically something that functions as either a switch which can be on off or as an amplifier taking an input signal and making it large so you can think of all kinds of situations when you might have a transistor of course you put them together in Banks and create computers and memory and all kinds of things and we also have a Transformer which is literally taking an input voltage and changing it to an output voltage depending on what you need inside of your circuit that has an AC signal like that so these are the most important ones folks I mean honestly I didn't really have to do this section because what we're going to do from here on out is really study resistors and sources and really understand how these circuits are constructed so I could have skipped this but I really wanted to give you some motivation I really wanted to to show you that it's not hard to understand what an inductor does it's not hard to understand basically what a transistor does and if you stick with me and if you learn these things you'll get very good at this stuff and when you get onto the more advanced courses and you'll be designing amplify fires you could literally go to the store and buy some transistors and buy some resistors and capacitors and hook them up and make your own amplifier you could literally do that once you understand how circuits work that's why I find them fascinating so watch this a few times make sure you understand it and then follow me on to the subsequent sections where we'll start to really roll up our sleeves with the basic laws of electric circuits and how to analyze them so the first one is what we call a source voltage and a lot of times it's really just a battery but in electric circuits it really doesn't matter exactly where the power comes from I mean you get into that when you actually build the circuit but you know from a theory point of view it doesn't really matter as long as it has a certain voltage and it can push current out of it we call it the source voltage so the most common thing you're going to see in a classroom environment for to draw or denote a source is a circle like this right now inside that circle is going to be plus minus and we've kind of talked about that a little bit and you'll have a label somewhere over to the side or maybe it's even inside maybe this is 20 volts 20V and we've already talked about that the units of a voltage I mean I'm just going to be kind of clear about this the units when you're talking about a source voltage is volts and I'm going to put in parentheses V so this is volts but just keep in mind that if you have a really teeny tiny Source you might be talking about millivolts or microvolts or nanovolts or something really really small if you have a very large Source very high voltage you might have kilovolts or megavolts or even gigavolts or something like that so you're using the metric system but the base unit I should say this is the base unit the base unit is the volt all right now we've most of the time in your in a class you'll see your Source written like this it'll have a circle plus minus we've already kind of discussed that we've given you a little bit of the details of of what this really means basically your current in the turn in terms of real life the electrons in real life are coming out of this negative terminal going back around through your circuit to the positive but we already talked about the theory there in reality when we're drawing all of our currents when we're doing all of our calculations we're not going to consider the current coming out of this negative terminal even though in real life that's really where the electrons are coming from instead we're going to talk about what we call the hole current which is the current it's kind of fictitious so to speak but it comes out of the positive terminal like this so it makes it much simpler when you see plus minus on a battery or on a source or something the current that you're going to use in your calculations comes out of this positive terminal and goes down around through the circuit back up like that so in most of the time you're going to see The Source written like that but if you have a circuit that you're looking at you might actually see it drawn like this I'm going to show you this you might see it like this with a bunch of little lines like this like this right and you'll also have some kind of volt so maybe nine volts when you see it written like this with a bunch of lines like this it means it's a battery it means it's it's literally one of those little batteries you can buy from the store I mean not always the case depending on who's drawing the circuit they may have different intention but most of the time when you see it written like this it means it's actually a battery whereas this can be anything it could be a battery it could be a power supply maybe I go buy a power supply from the store and I turn it up to 20 volts right maybe it's got an adjustable knob and I crank the 20 volts so it's a generic symbol this is usually when you see this usually it implies that there's a physical battery in the circuit now let me show you a couple things very very important usually you will not see a plus or minus written on this guy but it's inside of a drawing when you look at this notice I drew one of these guys with a long line and then I had a short long short long short and the last one I had is a short one all right so the short one which is this one in this case is always the negative terminal the long one which is always the case you're always going to have a long and a short it's always going to be the positive terminal so even though it may not say it on your drawing the long line that's at the top in this case is positive and the short one's negative don't worry about how many little little sandwiches I wrote there that's not that important it just depends on who's drawing it but you can put as many as you want really right there it doesn't doesn't really matter that much it's it's trying to tell you that there's little cells kind of in series there adding up to this voltage but from a big picture symbol point of view all you're looking for is the long line telling you it's positive in the Short Line telling you it's negative and the positive terminal here's where the current comes out and goes back around just like in this case so it's it's really the same thing so you might see it drawn both ways all right but obviously you got to start somewhere power source is where we're starting here because every circuit is going to have a voltage source of some kind now let's look at this picture here of a real battery if you inspect a battery long enough you'll find that one of the terminals is labeled positive and one of them is labeled negative so you can match that up to your drawing and kind of put it in place in the right orientation but when you hook it up in the circuit this is telling you this is the positive terminal this is where the current comes out negative terminal is on the other side okay now the next most common circuit component most important circuit component is one that we've actually already talked a little bit about in the last section it's called the resistor and we talked about that in the context of the electric current the current that's flowing a resistor is trying to resist that current it's really trying to slow it not slow it down it's not trying to slow the speed down it's trying to to limit how much current is in that circuit or maybe in that branch of a circuit maybe you have a circuit with two branches maybe you want a lot of current flow over here maybe you don't want so much current flowing over here it may depend on how you've designed your circuit so we use resistors to pull that off if we didn't have any resistors we really really have a lot of control over how much current goes in different legs of the circuit so that's really why they exist so number two is the resistor and it resists current now the symbol that you'll see universally for a resistor right is going to be basically a zigzag like this and next to the zigzag you'll have some number maybe in this case it's written like this 10 ohms so the base unit of a resistor foreign is equal to ohms which you write as capital Omega of course you might be talking about kilo ohms or Mega ohms or maybe even milliohms if it's a small version so metric system applies but the base unit is what we call an OHM you'll always see a resistor John as a squiggly line the squiggly line kind of represents uh if you think about current coming through there it's kind of like giving it a hard time it's like trying to resist it it's kind of like zigzagging getting in its way think about it that way that's why a resistor has that that guy here now let's take a look at an image of a resistor here and you'll see that it's just a discrete little component you can put them anywhere in your circuit that you need and different resistors that you purchase are going to have different values some of them may be 10 ohms some of them maybe 100 ohms some of them maybe a thousand or a million ohms and you have different uses for different values now the resistors are usually a little bit too small to actually print how many ohms are actually on there so if you notice in this picture there are different color bands that go around this resistor and we will talk about that a little bit more later but the different color bands tell you there's a there's a decoder ring so to speak where you can look up the colors and figure out what the value of this resistor is just from the color bands that are on the resistor so usually you will not see 10 ohms 20 ohms 30 ohms printed on the resistor but these colored bands basically tell you what the value of the resistor is without actually having to print it on there all right now the next most common circuit component that you're definitely going to see in almost every circuit is what we call a capacitor now I'm going to be honest with you we're not going to talk about capacitors in really any detail until much much later in the class because we're going to spend a lot of times with resistors and circuits with resistors but capacitors are very very common and in a nutshell a capacitor is just a device that stores electric charge you can think of it like that you may have seen it in a movie as a flux capacitor right it's it's kind of like the movie language right there a real capacitor is a device it's a small device similar size to a resistor but it doesn't resist the current flow in the same way that the resistor does what it does is it lets you pile up electric charge inside and then at a later time it lets you bleed that charge out maybe to feed another part of the circuit all right so let me draw the symbol and we'll come back around and I'll tell you a little bit of the Practical reasons why you would use a capacitor so what we have is what we call a capacitor right now the symbol that you see most of the time for a capacitor will look like this it'll have two parallel lines you know like this now the units before I get and show you exactly why this is important the base unit is the farad farad so you you might see that as F but in reality when you start purchasing capacitors or building capacitors or whatever a farad as a unit of capacitance is any enormous amount of capacitance it's an enormous amount of ability to store charge so you're never going to find a capacitor at a store or in a mail order catalog with a value of three farads it's never going to happen because to get a capacitor that could store that much charge would be enormous right so almost always you'll actually see micro farads or or even Milli farads maybe but most of the time you'll see it as micro farads so this is at 1 1 millionth of a farad and so you might see a 2.4 microfarad capacitor or a 3.8 microfarad capacitor and it's giving you a relative indication of how much energy can be stored in that capacitor so let me go back full circle a little bit and explain what this thing is doing the symbol is two parallel lines but notice they are not touching right they are not touching at all in the middle here so you can kind of think of the real capacitor as looking just like the drawing you can think of a real capacitor as having a plate right of large surface area plate you can't really see exists in the board but imagine like a plate sticking out and then another one right there and the distance between them I've drawn large here but the distance between the plates in a real capacitor is incredibly tiny in fact the closer you can get it to the next plate over without touching it the better so if you wanted to build a capacitor you could put air between them to separate the plates but in real life they might actually put plastic between them or some other non-conducting material something that does not conduct electricity goes between those plates so you intentionally do not want those plates of the capacitor internal to that device to actually touch you do not want them to touch in fact if they do touch your capacitor won't work at all so what's going on here is if I send a lot of electric current in here this direction then yeah it's true this is not connected it will not continue on however electric charge will begin to pile up on this plate it will begin to pile up on this plate and because if you think back to your physics anytime you have a bunch of electric charges piled up what do you think is going to happen if you charge up an object right you're going to get what we call an electric field which don't be too worried about that or scared about that what it basically means is if you charge a lot of think about shuffling your feet along the carpet on a dry day you've accumulated a lot of charge now you put your finger next to the doorknob and zap the charge jumps off right that's because you've accumulated that charge what you're trying to do here is allow this capacitor to build up a lot of charge right why do you think you might want to do that well you can kind of think of this almost like a temporary battery it's a sort of like a temporary storage device for electric charge in between this plates because you've got so much charge you're going to have a very strong electric field in there and that electric field is kind of like stored energy so that stored energy is stored in the form of that electric field there and when you decide to bleed this storage charge out maybe at a later time then you can kind of gain that energy back that you were storing in the first place so the most common example that I can think of of when you would want to use a capacitor um well they're using everything okay first of all but the thing you probably have a lot of experience with is your camera your uh not your digital cameras like your iPhones but your your actual point and shoot camera where you can hear it when you hear it charge up you hear that whiny sound like it's getting really really whiny what's going on there is a lot of electric charge is coming in from the battery and filling up a whole bunch of capacitors there's a lot of capacitors in there and they're wired up together and they're charging those capacitors getting them really really really really charged and then notice on your camera it takes a few seconds for that light to come on to tell you all right ready to go with the flash that light takes time to charge up because these capacitors take time to actually accumulate this charge the reason that you have to accumulate that much charge in a capacitor Bank to fire a flash is because that flash bulb is actually a little bit of gas inside of a bulb basically and it takes a lot of electricity to jump in there and basically cause that gas to to ionize for the electrons to jump around and release all that white light so if you hook your battery directly up to the flash bulb nothing will happen because there's not enough you need it to happen like it instant it's like it's like shuffling your feet across the carpet you build up that charge and you touch the doorknob and at that moment it's like a little lightning bolt went off and jumped across to the doorknob same thing for the flash you've got to accumulate a lot of charge there and then release it all at once into that gas that's in the in the flash bulb and then whamo the gas releases a lot of light and you can do it over and over and over again this is probably one of the most intuitive ways you could think of when you would want to use a capacitor so it's a storage device you put charge in later on you can take charge out that's the simplest thing the energy that's stored in a capacitor is because the charge on the plates here that are not touching but also in the electric field that exist in between the plates when you charge it because when you put all those charges there that electric field is going to going to be there anytime you put those charges there so if we look at this picture of a capacitor that we have on the screen now you can see what they sort of look like a lot of times there's different shapes and sizes but this one you can see the shape there and notice that the value of the capacitance is written right there on the side so there's no fancy bands or color codings to decode usually for a capacitor the value is written directly on the capacitor so you can see that here and they all come in different shapes and sizes a physically large capacitor would be able to basically store more charge a physically small capacitor which might be inside of your computer maybe more delicate may not be able to charge as much but that's okay you may not need to charge that much for your application there in the computer there's a lot more uses for capacity faster than flash bulbs but that's the basic idea very very common circuit component all right let's go on to the next most common thing that you'll see or you'll hear of and that's called an inductor inductor is probably something you may not have heard of unless you're a circuit buff or something you've been studying this before lots of people have heard of volts a lot of people have heard of resistors lots of people have heard of capacitors even if it's just from a movie you may have heard of but not that many people have heard of inductors unless you really have kind of studied circuits a lot so an inductor in its simplest form let me go ahead and write this down it's called an inductor it's got really a cool name actually inductor like a conductor but it's inducting something it looks like this it looks totally different than any of these things you go here and you basically do it draw like a little spring it looks like a spring but really it's representing a coil of wire and the units of an inductor is the Henry and you'll see that as H the Henry now of course you might have Micro Henry's you might have Millie Henry's you might have Nano Henry's you might have kiloh Henry's you might have different modifications to the base unit for metric system but the base unit is a Henry now what do you think this coil of wire could possibly do uh well I'll tell you if you if you uh think about it you have to think a little bit back to physics here okay a little bit with me so I'll give you a little bit of a basic physics lesson what you do when you coil a wire like this let me back up from a coil forget about coil for a second if you have a straight wire just a straight wire and you run an electric current through it then nature is going to produce a magnetic field around that wire you don't have to do anything you don't have to design it specially it's just fact a magnetic field just like your magnets that are stuck on the fridge will pop up and exist as soon as you run an electric current through a wire if you hook a nine volt battery up to a wire and you get some current going if you had a magnetic field detector you would detect a magnetic field around that wire now turns out that energy right the potential to do some kind of work is stored in that magnetic field just like there was energy stored in this electric field so it's something that's maybe not quite so intuitive but if you think about two magnets and you're holding them apart like this and you're physically holding them apart right because they're trying to attract one another well there's energy in that magnetic field it's trying to pull those magnets together and you are resisting that so you know that there's energy there's potential to do work in that magnetic field because you've you've played with them you know that they push and pull and all kinds of things so a magnetic field can do bona fide work right so what we try to do when we construct an inductor is we try to make a device and this is important that will concentrate that magnetic field and make it stronger so that we can store even more energy inside that magnetic field and that is exactly what an inductor actually does because if you take that wire and you look at its magnetic field it goes around the wire but if you take a wire and you coil it up like this then what if you can think of a cylinder like think of a cylinder coming from me to you and I take a wire and I wrap it around the cylinder like think of a paper towel tube or some kind of pencil maybe and I'll wrap a tight wire around around the cylinder like maybe I do 100 turns maybe I do 500 turns maybe I do a thousand turns maybe a really small wire and I wrap it a thousand times like this all the way from me to you then it turns out that if you run an electric current through this very long coil of wire that the magnetic field inside that coil inside the coil is going to be very very strong and the stronger the magnetic field then the stronger and the more energy is stored in that magnetic field so what you're doing is you're creating a situation where the magnetic field adds together inside and gets very strong and so that's what an inductor does it's a storage device to store energy but not in the form of an electric field it's storing it in terms of a magnetic field of course electricity is what's generating the magnetic field and that's you know why it's useful in an electric circuit but ultimately the energy that's stored in an inductor is because of the concentration of that magnetic field inside of the inductor so that's a lot of theory now if you were to look at a picture of an inductor literally it's a coil of wire so it's it's literally a coil of wire that's all it is you could build one in your house now the more turns you have on that coil the the higher the inductance is what we call so the more henries you have and also if you put different materials inside of this coil you're going to affect the inductance if you put metal of course you have an insulated wire you don't want it to touch the metal but if you put a metal in there it's going to concentrate the magnetic field a little bit more you're going to change the inductance a little bit and so on so there's different ways to construct them but ultimately you're just trying to make that that inductance a specific value for your application all right so before I go on I want to give you another little bit of philosophy here kind of give you the big picture because this stuff this capacitance and inductance stuff students don't usually learn about any of this stuff until weeks or months into their studies of of electricity right because it's usually just focus on resistors resistors resistors and we're going to do the same thing but I really wanted to give you some motivation step back with me for a second and realize that a capacitor and an inductor a really nice mirror images of one another when you think about it right I told you a capacitor is constructed to basically concentrate the electric field the electric field inside the plates to store energy in the form of an electric field between the plates the inductor is specifically constructed to store energy but not in an electric field as a magnetic field that's inside the coil this guy stores energy as a electric field this guy stores energy as a magnetic field electricity and magnetism kind of go hand in hand heck I even already told you that an electric current generates a magnetic field right it turns out you can also generate electricity from magnetic fields in fact that's how our generators work at the power plants you have steam that turns generator well inside the generators a bunch of magnets and a bunch of wire and when you turn them like that out pops electricity so electricity and magnetism are tied the hip you really can't have one without talking about the other and it's a fascinating part of nature you know that they're invisible and we know they're there but they're somehow tied at the hip what what we do with these two guys is a lot of times we put them in circuits together to perform a function and the best example I can tell you when you would really use an inductor is when you would put it in a circuit with a capacitor to build a radio now I'm not talking about the Digital radio it's a fancy stereo system I'm talking about think about to older radios when you can open it up and see a bunch of wires running around everywhere there was no computer chips in the early radios I'm talking about your basic radio you're basically going to have a circuit in there that's going to try to receive receive signals over the air and play them through a speaker well inside of that radio you've got capacitors and you've got inductances and you have chosen those values such that when you turn the knob by the way when you turn the knob usually you're changing the value of the capacitor in the circuit when you turn the knob on the radio you're changing the value of this capacitance when you do that these two guys are in the circuit together and they it's kind of hard to explain without showing a real circuit but basically since this guy stores energy in an electric field and this guy stores energy as a magnetic field when the wave comes in you get this situation where they start sending energy back and forth to one another the capacitor sends energy into the into the inductor and the inductor kind of collects that energy and then on the next cycle it sends the energy back to the capacitor and it goes back and forth in this perfect harmony it's called resonance it's very perfect harmony when they kind of send this energy back and forth and at that moment of resonance when they're both doing that perfect dance of sending energy back and forth that is the frequency of the wave that you're receiving and that's what gets sent to the speaker so it's kind of like you can think about the wave comes in hits the antenna and goes to these capacitors and inductances of course you can tune the knob and change the value of this capacitance and when you do that you're changing the way the circuit behaves so that that frequency that you want to the radio station you want to listen to is the one that gets sent to the speaker because of this perfect dance of energy between the capacitor and inductor all right that's about as much as I want to say about it because honestly you can't truly understand it until we do a lot of math and a lot of equations but big picture that is what's happening when you tune a radio you're changing this value of capacitance to perfectly resonate or tune with the inductor that's also there thereby letting that particular radio station get sent onto your speaker and that's really what it's mostly used for at least in terms of you know radio technology but inductances of course have lots of other uses as well all right so the next circuit component certainly these are the most common circuit components you could spend a year studying circuit Theory just with these four components and I could stop here in fact I thought hard about stopping here because we're not going to talk about the other other circuit components that I'm about to draw for you for quite a long time but I did want to give you an overview give you a little motivation the next circuit component that's very very common is called the diode and a lot of you may have even heard of what a diode is basically a diode only allows the electric current to flow in One Direction it's like a it's like a one-way switch right it will not let electricity go this way but it will let it go that way right so let's let me let me show you what that looks like number five we call it a diode dial just like that all right now a diode the symbol for it looks like this you've got a triangle with a line on the end of the triangle like this it would look just like this in an electric CERN in an electric circuit now when you see it drawn like this what this means is current can only flow can only whoops own only flow this way in other words if I hook a battery up to the circuit and try to let current go this way it will be able to go this way it will go this way all day long no problem it's like a wire it doesn't present much resistance it doesn't get in the way it just lets it go that way but if I take that battery and turn it around and try to force electricity to go this way it will not flow it will not flow that direction all right now if I hook a big enough battery to it or a big enough generator to it to kind of like overpower this thing sure I can do that I'm going to burn it up literally smoke will come out of it it'll burn up and then of course lots of things can happen then but in normal operation it's only going to let electricity go One Direction there's tons of applications for that I can't really get into them now because you have to draw a big circuit to show you but I think that even even though you you may not know the specific applications I think you could see the utility of something like this think of think of the hardware store where you might find a valve that only lets your water go One Direction there's lots of reasons you might use that if you're building a sprinkler system right same thing in a circuit there's lots of reasons when you would not want current to go a certain direction because maybe it'll damage a component or maybe that part of the circuit that you're designing you only want current to go one way so you just stick a diode in there it's not going to affect anything this direction it's going to let everything work normal but if any kind of current tried to go the other way it's going to block it that's a very useful thing so that's what diodes are used for the next guy after a diode that I know all of you have heard is called an l e d lots of people have heard of LEDs but not as many people know that led stands for light emitting diode so if you know that already congratulations it's light emitting diode but a lot of people do not know that led stands for light emitting diode so it's a diode just like this one that also happens to emit light that's all it is so if you were to draw it it would look just like a diode with one small change you have a triangle like this but you have on a circuit diagram you would see two little squiggly lines maybe one maybe two depending on who's drawing it this represents the light that's coming out of this diode so this basically means that if I hook a battery up this way and let the current go this way because this is the direction I can allow current to flow through the sky then the current will flow and light will come out as a byproduct that's just constructed that way they're built in the lab that way so that when current goes through light is generated inside and comes out the details of how that works is totally for another course that's very very uh amazing Discovery in the 20th century actually to build these things but that's how they work there's no light bulb filament inside there it's just the way the thing is designed with the Silicon that basically that's inside of there all right but if I turn my battery around and go the other way then nothing happens no current can flow no light comes out so it serves a double function it serves the electricity blocking feature and it also happens to emit light now it's useful for lots of different reasons but of course you see these things all the time almost every electric device out there has a little red indicator light or green indicator light or a blue indicator light those are just different kinds of LEDs that are built slightly differently to emit light with a different color all right okay so here is a picture of a regular old diode it's just a a discrete component it's about the size of a resistor and notice that there's a band on one end that band is telling you where that flat piece comes from that's on the front of that triangle that tells you that the electric current flow can go this direction from this direction to the direction that has that band on there that's telling you the orientation of the diode all right now here's a picture of a light emitting diode you can get them in all shapes and sizes and also in many colors and you can see from the color of it that if you send electricity through it the thing will light up if you hook your battery up the other way no light's going to come out and obviously no electricity is going to flow through it either learn anything at mathandscience.com

Channel: Math and Science

Views: 8,896

Keywords: transistors, electronic circuits, circuit components, resistors, capacitors, inductors, diodes, op-amps, amplification, electronics, electrical engineering, semiconductor devices, field-effect transistors, bipolar junction transistors, FETs, BJTs, circuit design, electronics tutorial, electrical components, electronics basics, transistor applications, transistor theory, transistor types, transistor basics, circuits, circuit analysis, circuit theory, ohm, volt, ohms law, short circuit, tutor

Id: KwVtglA4gnQ

Length: 42min 49sec (2569 seconds)

Published: Tue Jun 06 2023