Understanding Capacitors in Electronics

Kota Moore explains capacitors' functions, types, symbols, and working principles, emphasizing their capacitance ratings and usage in circuits.

### Capacitors: Types, Working Principle, Schematic Symbols, Units, Time Constant, and Capacitors in Series and Parallel
* 💡 Capacitors are electronic components that store electrical charge and act like **mini batteries**, with various types such as electrolytic, ceramic disc, and poly film capacitors differing in **polarity and usage**.
* 🔋 Electrolytic capacitors are polarized and have a voltage rating, with the **longer lead being the anode**, while ceramic disc and poly film capacitors are **non-polarized**.
* 🛠 The basic structure of a capacitor consists of **two conductive plates separated by a dielectric material**, and when connected to a battery, one plate gains **positive charge** while the other gains **negative charge**.
* 📝 The unit of capacitance is the farad (F), but in electronics work, **microfarads (μF)** and **nanofarads (nF)** are commonly used due to the **large value of a farad**.
* ⏳ The RC time constant (τ) of a capacitor is calculated as the **resistance times the capacitance**, representing the time it takes for the capacitor to **charge to 63% of its maximum voltage**.
* 🔌 When capacitors are connected in series, the total capacitance is calculated as the **reciprocal of the sum of the reciprocals** of individual capacitances, while in parallel, the total capacitance is the **sum of individual capacitances**.

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, we'll 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

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. 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 farad, and the farad 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 farad unit. In fact, we won't be dealing with farads at all. Instead, we will probably be dealing mainly with the microfarad denoted by this weird little letter, kind of like a capital letter F. This is a microfarad, and a microfarad is one millionth (0.000001) farads. So many of the capacitors that we will be using are measured in microfarads, not full farads themselves. We may also be using nanofarads. This is a nanofarad, and a nanofarad is even smaller. It is one thousandth of a microfarad, so it is extremely small. These are the two units of farads that we'll be using because, like I said, a farad 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 of a 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 at 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 plate 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 gained electrons, 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 plate is 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 equalize 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 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's 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 onto 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 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 farads.

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%. So, after this many seconds, a capacitor of capacitance, whenever we plugged in here to the equation, we'll have 63% of the voltage accumulated within the capacitor. And it's generally safe to say that it's 98% charged, so close to 100% 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 microfarads, which is the same thing as 0.001 farads, of course. So, if we did this, we got tau or the time constant to equal 10 seconds. So, in this scenario, with 10,000 ohms of resistance leading up to a 1,000 microfarad 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 tau 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 F1 and F2, 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 denote as \(C_{\text{total}}\), is going to equal 1 over all of the capacitance ratings together. 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 \(C_{1} + C_{2}\) 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.

Beginner Electronics - 19 - Capacitors

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Understanding Capacitors: A Beginner's Guide

Capacitors are like mini batteries, able to store electrical charge, and they come in various shapes, sizes, and types.

Electrolytic capacitors are common in tutorial series, with the longer lead being the anode and the shorter lead being the cathode, marked by a stripe with a negative symbol.

It's crucial to remember that capacitors have a voltage rating, indicating the maximum voltage they can handle in a circuit.

Ceramic disc capacitors are non-polarized, allowing for flexible lead connections in a circuit.

This is in contrast to electrolytic capacitors, which are polarized and have specific lead orientations.

Poly film capacitors, like disc capacitors, are also non-polarized.

The schematic symbols for capacitors vary based on polarization, with straight lines representing the more positive side and curved lines representing the more negative side.

Capacitors are rated in farads, and while the technical details of this unit are beneficial to know, a basic understanding of the farad unit is sufficient for this tutorial series.

Understanding Capacitors: The Basics of Farads

Capacitors in electronics work are mainly measured in microfarads and nanofarads, due to the impracticality of dealing with full farads in this context.

A capacitor's basic structure consists of two conductive materials separated by a dielectric, allowing it to store and release electrical energy in a circuit.

By connecting the capacitor to a battery and then to a circuit, it can power the circuit for a short time before discharging.

The Operation of a Capacitor in a Circuit

When connected to a battery, a capacitor's plates become positively and negatively charged, with the charges separated by the dielectric material.

Disconnecting the battery leaves the plates with a difference in charge, and connecting them to an LED and a resistor allows the charges to equalize, generating a current flow.

This current flow is the result of the capacitor causing electrons to move from one plate to the other, similar to the function of a battery.

The Role of Capacitors in Allowing Current Flow

The schematic symbol for a capacitor shows a gap because no current actually travels through the capacitor itself.

However, when a capacitor is connected in a circuit, it allows current to flow through the component, facilitating the motion of charges and the creation of electricity.

The time constant (tau) for capacitors, calculated as the resistance multiplied by the capacitance, determines the amount of time it takes for a capacitor to charge to 63% of its voltage, with it being almost fully charged after four time constants.

When two capacitors are in series, their capacitance values are not simply added together like resistors in series, but rather their combined capacitance follows a different calculation.

Capacitors in Series and Parallel: Total Capacitance

The total capacitance in a series circuit is calculated as the reciprocal of the sum of the reciprocals of the individual capacitances.

In a parallel circuit, the total capacitance is simply the sum of the individual capacitances.

Understanding these calculations is essential for working with capacitors effectively.