Beginner Electronics - Beginner Electronics – 19 – Capacitors

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Beginner Electronics

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Beginner Electronics – 19 – Capacitors

what is going on everyone my name is Kota Moore and welcome back to electronics episode 19 in this episode we are going to learn about capacitors

now capacitors are able to store electrical charge and they act kind of like mini batteries now they're not exactly like batteries but that's just one way to kind of think about it for

now don't worry we'll get into a more advanced explanation in a little bit but for now let me show you some of the most common types of capacitors because capacitors like many of the other

electronics components come in many different shapes sizes and types perhaps one of the most common types of capacitors that we'll see and probably one of the main capacitor types that

I'll be using throughout this tutorial series are the electrolytic capacitors which are shown here now electrolytic capacitors can be very small and they can be very large of

course in this tutorial series will probably be only dealing with the smaller of the electrolytic capacitors now when we learned about LEDs we know that one of the metal leads coming from

the LED is longer than the other and that means it's the anode or it has to be connected to the more positive part of the battery now electrolytic capacitors at the exact same way as you

can see on this capacitor at the right here you can see that this metal lead here is much longer than the other metal lead here so the longer of the two metal leads in

this case this one would be the anode or it would have to be connected to the more positive side of your circuit while the shorter leg over here would have to be connected to the more negative side

of the circuit that's very important to remember whenever you're working with electrolytic capacitors another way to tell which of the leads of the capacitor is positive or which is negative many of

the electrolytic capacitors will have a stripe on the side of them with a negative symbol and some arrows that means the lead that is closest to this stripe here should be the cathode or

should be connected to the more negative side of your circuit on the electrolytic capacitor on the right here we can't see that stripe but we know because of this shorter lead this must

be the negative part or the cathode it's also important to remember that all capacitors have a voltage rating on the capacitor on the left here you can see upside-down it says 35 V that means this

should be placed in a circuit of a maximum of 35 volts you should not put this capacitor in a circuit with more than 35 volts so it's also important to keep an eye on the voltage maximum that

these capacitors have those are electrolytic capacitors let's move on to another type of capacitor this capacitor here is called a ceramic disc capacitor and they're probably the second most

common type of capacitor that we'll be using in this tutorial series they're called disc capacitors because as you can see the top of them are shaped kind of like a little flat disc

now these capacitors ceramic disc capacitors are not polarized so you can put either this lead as the anode and connect you to the plus side and this lead to the negative side or you can

even do it the other way around you can make this the negative side and this the positive side it doesn't matter which way you connect ceramic disc capacitors together so that's one of the main

differences between ceramic disc capacitors and electrolytic capacitors you can connect ceramic disc capacitors in any way that you want in your circuit the third type of capacitor that I'm

going to show you are called poly film capacitors and just like disc capacitors they are not polarized meaning you can connect either this lead or this lead to the positive or negative side of your

circuit it doesn't really matter I'm probably not going to be using any of these film capacitors within this tutorial series but it's probably another type that you might see in some

electronics work so we've seen the capacitors now what the heck do they do and how do they work now before I get too far into the explanation of capacitors let me just show you the

schematic symbols for capacitors now there are two main schematic symbols for capacitors that you will see and these are them the first schematic symbol that you'll see here is often used for either

a ceramic disc capacitor or any capacitor that is not polarized it doesn't matter which way you connect the leads most often they're used like that but of course you might just see this as

a general form of a capacitor in a schematic the other form of schematic symbol for the capacitor over here on the right is generally used for polarized capacitors like electrolytic

capacitors as you can see instead of two straight lines we have a straight line and a curved line over here now this straight line generally signifies the anode or the more positive side of the

component while the curved side represents the cathode or the more negative side of the component so that's the important difference between the two schematic symbols generally when you see

one of these it's probably an electrolytic capacitor because it is polarized so let's move on to how these capacitors work now all capacitors have some type of capacitance rating

in the unit fair at and the fair I'd unit is often denoted by the capital letter F like so now the third unit we don't really need to know for our purposes the technical details of what

the unit actually means of course it would be very beneficial if you did know the technical side behind the farad unit so if you want to know that go ahead and do a bit more research online that would

be very beneficial however for our purposes for this tutorial series we just have to be familiar with the farad unit and that should be good enough to continue following along with the series

and eventually building a big computer now one farad is actually a very very very large value for our type of electronics work we won't even be touching a full fair eyed unit in fact

we won't be dealing with fair ads at all instead we will probably be dealing mainly with the micro farad denoted by this weird little letter you kind of and the capital letter F this is a micro

farad and a micro farad is one millionth 0.000001 farads so many of the capacitors that we will be using are measured in micro farad's in not full farad's

himself we may also be using nano farads and F this is a nano farad and an Arial farad is even smaller it is one thousandth a micro farad so it is extremely small these are the two units

of farads that we'll be using because like I said a ferret is a very large value for the type of electronics work that we will be doing so this is what a capacitor does here I have a very simple

circuit it consists of an LED and a resistor just hooked up in a regular circuit now I have a 9-volt battery here and I have a 1000 micro farad capacitor so what I'm going to do is I'm going to

take the negative or the cathode side of the capacitor touch it to the cathode side of the battery and the positive side of the capacitor to the positive side of the battery just for about a

second or two then I'm going to hook up the negative side of the capacitor to the negative power rail on my breadboard and the positive side of the capacitor to the positive power rail and as you

can see the LED lights up and then slowly begins to dim as the capacitor discharges now one quick note please don't go out and just shove a capacitor anywhere in any circuit just yet because

in order to do that properly and safely you're going to need another electronics component that we haven't talked about quite yet all right so what happened in that circuit we

touched the capacitor to the battery just for a few seconds and then we plug the capacitor into our circuit and all the sudden it powered the LED for a few seconds and then the LED began to dim

down so what was it about touching the capacitor to the battery that made this work now capacitors are made in many different ways but the basic form of a capacitor is you have a piece of

conductive material and you have another piece of conductive material now these two pieces of conductive material are separated by usually a very very very thin layer of a dielectric material

which is mainly an insulator so essentially we have two metal sheets separated by a very very very small amount of insulation and that is the basis of all capacitors and how they

work so something as simple as literally a piece of metal with a tiny bit of separation from another piece of metal can power up a circuit so let's take a look what goes on when we actually

connect this to something like a battery here is sort of a side view of what I just showed you these two places here are the two pieces of conductive material and just think that they're

flat up against each other and separated by a tiny little sliver of dielectric material so without any battery power or anything these plates have some positive and negative charges on them and they

probably have roughly the same amount of positive and negative charges on both of the plates all right well that's fine and dandy but what happens when we connect these plates to the batteries so

essentially when we connected the capacitor to the battery one of these plates was being connected to the cathode and one of the plates was being connected to the anode essentially so

that caused any negative charges on this plate here to flow out and through the battery which basically left this play as mainly positively charged with a bunch of positive charge on it whereas

this plate over here gained many many electrons or negative charges right they it gained electron so it's more negatively charged now and as we kept this battery plugged into the capacitor

these charges kept on separating and a bigger difference between the two plates now because these two metal plates are so close together these charges actually get attracted to the

edge of the plates or towards one another rather so since each plate has more of a number of opposite charges they try to attract attract each other really really closely but they can't

quite make it there because of the dielectric material in between so that's what happened when we plug the battery in now let's say that we disconnected the battery here we broke off the

connection these plates still have that difference in charge now instead of the battery here we hooked up the exact same capacitor after it's all charged up and it has a large difference between the

two plates we then hooked up these two plates to instead of a battery in LED and instead of drawing everything out here I'm just going to draw a circle to represent the

LED but there was also a resistor in there so when we connected this up to the LED and let me just mark that here this was the LED here basically the charges began to equalize now it doesn't

matter which way you think of it whether these negative or electrons were traveling through over to this plate or if the positive charges are traveling to this plate you can think of it either

way but one way or the other this plate began to lose some of its negative charge through the LED right through the LED and onto this plate so now this plates gaining negative charges here and

then of course maybe some positive charges going this way so this plate is beginning to gain positive charges because all the plates wanted to do this entire time are equalized their charges

have the same number of positive and negative charges on each plate so once that LED was hooked up to the plates they had a pathway to change out those charges so because all these electrons

are flowing through the LED that's essentially the same thing a battery does it it causes electrons to flow so if a capacitor is causing these electrons to flow from plate to plate it

generates current now it's important to remember that no current actually travels through the capacitor itself I mean the schematic symbol literally has a gap in between the circuit there

no current traveling through the capacitor however when you hook up a capacitor in a circuit like this it allows current to flow through the component because the charges are

traveling through the component on to the other plates which creates of course electricity that motion of all these particles moving through the electronic component so no current actually flows

through the capacitor itself but it can cause current to flow through your circuit and as we begin to use capacitors that you will become a bit more understandable for you alright so

now let's get some miscellaneous learning out of the way here now there is something called a time constant when it comes to capacitors called an RC time constant and that's signified by the

letter tau often and the equation is the tau equals or the time constant equals and probably saying that really bad the resistance times the capacitance right and capacitance is measured in farad's

of course where the time constant tau is measured in seconds and resistance in ohms this is the amount of time it takes the capacitor to charge 63% about so after this many seconds a capacitor of

capacitance whenever we plugged in here to the equation we'll have 63 percent of the voltage accumulated within the capacitor and it's generally safe to say that it's 98% charged so close to 100

percent charge after 4 tau periods so if that sounded like some nonsense let me try this we will calculate the time constant right so we have tau equals the resistance let's say we had 10,000 ohms

of resistance and our capacitor was rated at 1,000 micro farad's which is the same thing as point zero zero one farads of course so if we did this we got tau or the time constant to equal 10

seconds so in this scenario with a 10,000 ohms of resistance leading up to a 1000 micro farad capacitor it will take about ten seconds for the capacitor to charge 63% fully of its

voltage and it should be almost fully charged after four periods of the second so it should be fully charged after taua times four or forty seconds of being connected to your voltage source or

whatever now this is a pretty extreme example so that is how you can estimate the amount of time it will take for a capacitor to get fully charged now I know that this video hasn't gone too far

in depth with capacitors but I will explain one more thing in this tutorial series and that is what happens if we have two capacitors in series well in the form of resistors if these were two

resistors in series we would just add the resistance values together but when two capacitors are in series we do something a bit different so let's say the capacitance ratings of these

capacitors are F 1 and F 2 and that's not really the proper form to write those in but nonetheless let's continue here the total amount of capacitance the total capacitance rating which I'll do

TF is going to equal 1 over all of the capacitance ratings together dot dot so 1 over the total amount of capacitance is going to equal 1 over the capacitance ratings for all of your capacitors in

series this is the exact same equation essentially for resistors in parallel except don't get confused because this is for capacitors in series now if you were to have two capacitors in parallel

instead so let's say we have more of a situation like this in parallel instead the equation will look very similar to that when resistors are in series so basically the total amount of

capacitance rating is just going to equal F 1 plus F 2 and on and on and on so it's the same equations as resistors just flipped around when you're in series in parallel so that was today's

video on capacitors again the more that we use capacitors the more we're actually going to understand about capacitors and when to use them and how they work and everything thanks for

watching everyone and I'll see you guys in the next video

We learn about capacitance and capacitors, and how they work!

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