### Online-Lecture "Electronics"

Welcome to this course on "Basic Electronics". Here I offer a number of free modules from the fields of electrical engineering and electronics for students of all technical fields (e.g. mechanical engineering) as well as for interested hobby electronics engineers (and those who want to become one).​

The course will be successively expanded over the next few months (from mid-April 2020), with about 2 new videos per week. The following content is planned:

1. Basic concepts of electricity and electrical engineering

2. Basic electronic components

3. Simple circuits

4. Semiconductors and sensors

5. Operational amplifiers and filters

6. Integrated circuits

7. Microcontrollers (Arduino)

The idea is to convey the contents with a good mixture of theory and practical examples in such a way that learning is fun and the desire to try things out is created. In the experiments, I almost exclusively use components and tools that can be easily obtained for little money.

The shown slides can be downloaded under the respective video. If questions arise, the best way is to use the YouTube comment function - I'm happy to help.

And now have fun with your first steps into the world of electrical engineering and electronics!

Prof. Dr. Andreas Haja

### Electronics • Basic

##### Part 1.1.1 : Atoms & Charges

The theory part deals with the basic building blocks of atoms and their significance for electrical engineering. In particular, we look at electrons and protons, take a look at the periodic table of the elements and learn about electric charge as a cause of the force effect between particles.

In the tutorial part I will show you in a few short steps how to calculate the number of atoms and electrons in a substance, e.g. in a copper coin.

At the end of the videos you will have the necessary knowledge to understand the Coulomb force, the electric field and later also current and voltage.

### Electronics • Basic

##### Part 1.2.1 : Coulomb's Law

The theory part deals with all the essentials you need to properly understand the Coulomb force between charge carriers, such as electrons and protons. Also, I will show you the concepts of electron gas and drift velocity, which will enable you to fully understand where the famous Ohm's law comes from and how it can be derived from the Coulomb force.

The download links to all slides can be found below the second tutorial video.

In the first tutorial I will show you how you can calculate the Coulomb force between two point charges in a few simple steps. Also, I will show you what this has to do with a rubber balloon and a Tesla Model 3.

In the second tutorial I will show you how can calculate the amount of free moving charges in a piece of copper wire in a few simple steps. I will show you how to properly combine the atomic weight of copper, the Avogadro constant and the elementary charge into a simple and comprehensible equation, from which we can easily understand what current, voltage and resistance actually mean and which we can also use to derive the famous Ohm's law.

##### Part 1.3.1 : Current and Voltage

In this video I will explain how the electric current is defined and how you can derive voltage scientifically correct from the electric charge and from some material properties of a conductor. At the end of the video you will understand how current and voltage are connected by a simple equation and how Ohm's law results almost automatically from this.

And I will also show you what all this has to do with Benjamin Franklin and why we have been struggling with a false sign in many of the basic equations in electronics for over 300 years.

The download links to all slides can be found below the tutorial video.

##### Part 1.4.1 : Ohm's Law

In this video I will show you how the famous Ohm's law can be derived from a material-dependent relationship between electric current and voltage. We will take a close look at the factors which influence the electrical resistance of a material such as cross-sectional area and length but also electron density and mobility.

And by the end of the video you will be able to use Ohm's law to convert between voltage, current and resistance and you will also know what Ohmic materials are - because it is only these materials to which Ohm's law actually applies under all circumstances.

The download links to all slides can be found below the tutorial video.

##### Part 1.5.1 : Resistors

Resistors are one of the most common components in electronics. They limit the flow of current, divide voltage and current flows and, above all, they heat up because the potential energy of charge carriers is converted into heat energy inside them.

We have already looked at the terms current, voltage and resistance in the last video and have also derived Ohm's law. In this video I am mainly focused on giving you an overview of the different designs and applications of resistors and to help you understand what the color codes and E-series are all about.

Also we will have a look at what a potentiometer is and how you can use it to control the current flow so that the brightness of an LED changes. This video is mostly about theoretical aspects, but since theory alone usually doesn't do much, there is a follow-up video where we look at how to use resistors in practice.

The download links to all slides can be found below the tutorial video.

##### Part 1.6.1 : Electric Power

What is electrical power? How are power, work and energy related? And what do current, voltage and resistance have to do with it? In this video I will explain all of this to you! I will also show you one of the most common mistakes in combining the power law and Ohm's law.

The download links to all slides can be found below the tutorial video.

##### Part 1.7.1 : Kirchhoff's 1st Law : Node Rule & Parallel Connection

How does the electric current divide at branches? What are nodes within the electric circuit? How can the total resistance of parallel resistors be derived from Kirchhoff's 1st rule? Why does the total resistance decrease when we connect additional resistors in parallel? In this video I will answer all these questions for you.

In addition, I will also prove Kirchhoff's 1st rule for you in an experiment. In the previous videos we have only looked at a single component each time. Basically we connected single resistors to different voltage sources and conducted measurements on current, voltage and power. Now we will connect several components in a circuit with each other such that current and voltage are distributed across the components.

There are two elementary rules for this in electrical engineering, which are named after their discoverer, a German physicist called Gustav Kirchhof. In this video we want to look in detail at Kirchhoff's first rule, which describes what happens when we split an electrical circuit into multiple branches.

The download links to all slides can be found below the tutorial video.

##### Part 1.8.1 : Kirchhoff's 2nd Law : Loop Rule & Series Connection​

How are source voltages divided across resistors which are connected in series? What is a loop / mesh in a circuit? How can the resistance value of resistors connected in series be calculated from Kirchhoff's second rule? What is the difference between reference arrows for active and for passive components when setting up loop equations? In this video I will answer all these questions for you. #

In addition, I will prove Kirchhoff's 2nd for you rule in an experiment. Kirchhoff's first rule is a conservation law for the electric charge. And the second rule, which is what we will be talking about in this video, is also a conservation law, not for charge, but for energy. And where the first rule is about dividing current flow and about connecting components in parallel, the second rule is about dividing voltage and about connecting components in series.

The download links to all slides can be found below the tutorial video.

##### Part 1.9 - Arduino Mini-Project "LED Traffic Light"

The idea is to build a pedestrian light controller which consists of an Arduino to implement the control logic, a push-button for the pedestrians and a red and green LED for the actual traffic light. So when the pedestrian presses the button, the traffic light should switch from red to green, stay like this for a time and then switch back to red.

The question is, how you can approach such a problem. And as with most engineering tasks, the best way to approach a problem is to break it down into smaller pieces and then solve these one-by-one. And this is just what we will be doing with the pedestrian light project.

So let's identify the pieces: (1) First, we need to safely connect an LED to a voltage source so that it does not draw too much current. And this is what this first video will be about. (2) Then, in the second video, we will look into the Arduino platform, discuss the purpose behind of all the input and output pins and also write our first program, which will switch on and off the LED we have connected to it. (3) And finally, in the third video, we will to hook up a push button to one of the Arduino input channels so that we can detect when the control logic inside needs to switch off the red LED and light up the green one.

So we have a total of three problems to solve, and the combined solutions will make up the pedestrian light project. Let's go for it.

The download links to all slides can be found below the tutorial video.

##### Part 2.1 - Capacitor Basics

How does a capacitor work? What do we need it for in electronics? How can we control its charge and discharge time? In this video, I will answer these questions.

We will start with a typical problem you often find in electronics, which is called a "bouncing button" that makes a connection multiple times after it has been pressed once - which means that your circuits probably won't work as expected. And in the process of solving this problem, I will show you what a capacitor is, how its charging and decharging cycles look like and how you can build one yourself from two pieces of aluminum foil and two laminating pouches. And by the end of the video, you will know how you can use and dimension capacitors to mitigate the impact of noisy signals in your circuits, for example to debounce a push-button in an Arduino circuit.

The download links to all slides can be found below the video.