This course introduces students to the basic components of electronics: diodes, transistors, and op amps. It covers the basic operation and some common applications.

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From the course by Georgia Institute of Technology

Introduction to Electronics

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This course introduces students to the basic components of electronics: diodes, transistors, and op amps. It covers the basic operation and some common applications.

From the lesson

Introduction and Review

Learning Objectives: 1. Review syllabus and procedures of this course. 2. Review concepts from linear circuit theory to aid in understanding material covered in this course.

- Dr. Bonnie H. FerriProfessor

Electrical and Computer Engineering - Dr. Robert Allen Robinson, Jr.Academic Professional

School of Electrical and Computer Engineering

Welcome to the introduction to electronics.

Â I'm Dr. Ferri and this lesson will be a review of circuit elements, and

Â actually the next few lessons will be a review

Â of basic circuit type principles that you're expected to

Â know before you come into an electronics class, so they cover linear circuit

Â principles, so if you want to review these lessons, you're welcome to do it.

Â If you want to skip them because you're very familiar with circuit elements,

Â linear circuit elements, then you're free to do that as well.

Â In this lesson, we will review resistors, capacitors, and inductors, and

Â their current voltage characteristics, as well as looking at sources and nodes.

Â So let's look at these passive elements.

Â A resistor, a capacitor, and an inductor.

Â In each of these cases.

Â We show by convention that the current is going into the plat, the positive side

Â of the voltage, and with that sort of convention we get the equation.

Â So this equation corresponds to this convention where this arrow is

Â flowing into the positive side.

Â And this particular equation is called Ohm's Law.

Â The voltage is equal to current times the resistance.

Â The resistance is measured in ohms.

Â And the symbol is.

Â And omega. Now if I go on to a capacitor,

Â capacitor is an energy storing device.

Â And it has, it is governed by this differential

Â relationship between the current through the capacitor and the voltage across it.

Â And note again that the convention is to show the current going into

Â the plus side of the voltage and then we get this equation.

Â The, the units on capacitors are farads and

Â usually we'll, we'll be looking at units that are in 10 to the minus 6 farads

Â or represented as micro farads.

Â Those are common, more commonly seen.

Â Then we get to inductors.

Â Inductors are also energy storing devices and

Â the current voltage relationship is this.

Â Notice that now we're taking the derivative of the current to give us

Â the voltage.

Â The common units are henries.

Â Which we represent as H.

Â And it's oftentimes, we'll look at, ten to

Â the minus three, or millihenries.

Â So the range that we often look at is again, millihenries.

Â And notice again that the, by convention that the current is going into

Â the positive side of the voltage in order to get this equation.

Â These are called passive elements,

Â because they don't require a power supply just for that element.

Â There are other elements that we will see in electronics that we'll

Â call active elements that require a power supply to make them work,

Â to make them give their characteristics.

Â Now let's look at the basic series and

Â parallel connections of resistors, inductors, and capacitors.

Â The series resistors, you just sum them up.

Â So the total resistance from this point here to this point here

Â is the sum of the two things.

Â And inductors work the same way.

Â The total inductance between this point.

Â And this point is the sum of the two individual inductances.

Â And again, this would be in Ohms, and Inductors would be in Henrys.

Â Now the parallel connection's a little bit different.

Â Parallel connections,

Â meaning that the resistors are connected together at one end and

Â again at the other end, whereas in series they're connected only between them.

Â The resistance, total resistance between this and this, so it's equivalent

Â resistance across everything, is the inverse of the sum of the inverses.

Â Now if I only have 2 resistors I can simplify this.

Â So if R3 is equal to 0 and I only have R1 in parallel with R2.

Â So that represents the fact that R3 is equal to 0 and

Â I've only got two resistors in parallel.

Â Then that would be equal to R1 times R2 over R1 plus R2.

Â And we can get that by setting R3 to equal to 0 here or dropping that off of here.

Â And then just simplifying this form.

Â So, then we've got the same relationship for

Â inductors in parallel, this, this relationship here.

Â So, we would also say L1 in parallel with L2, L1 times L2 over L1 plus L2.

Â Now capacitors are little bit different.

Â They operate at, in a different way.

Â The series capacitors has a same equation that we use

Â before when we were looking at parallel resistors or any parallel inductors.

Â So.

Â Capacitors in series, you use this relationship.

Â Capacitors in parallel are easier.

Â The equivalent capacitance between this point and

Â this point is just the sum of the individual capacitances.

Â So, connections and sources.

Â When we look at a schematic, we'll see a ground.

Â It's very commonly used and the ground looks like this.

Â It's a reference for zero volts.

Â When we look at linear circuits with DC voltages maybe batteries supplying it,

Â we often times pick a ground and say that's our reference node.

Â And reference node meaning that we're going to say the voltage with respect to

Â anything else any other point in that circuit.

Â Is the potential, with respect to that Ground Node.

Â And so, it's just a reference node.

Â And when we get to electronic circuits,

Â it usually has a little bit more meaning to it.

Â Because we often times,

Â power these electronic circuits with AC or wall power, you know?

Â You plug it into the wall.

Â And when you plug it into the wall, we're connected to a power system.

Â In that power system, the power that comes into your house.

Â Usually is grounded, meaning that there's a connection down to the ground and

Â to the real ground, to Earth.

Â And so when the power supplies are connected to the wall and then they're

Â connected to your circuit, often times we are required to ground our circuit.

Â So in that case, the ground often times has a more physical meaning to it,

Â really relating to the ground, the true ground.

Â A Node is anything that has the same potential,

Â that's connected electrically together.

Â So, every point on here, is the same node.

Â Now, I might have different current going through these branches, leaving this node.

Â But the voltage everywhere on this node, is the same.

Â With respect to Ground.

Â Our Voltage Source, we have Independent Sources for both the Voltage Source and

Â the Current Sources.

Â Independent Sources will show as circles.

Â The volt, the units on a Voltage Source are going to be in volt.

Â Units on a Current Source are going to be in amps.

Â Oftentimes.

Â We supplied them with smaller amps, maybe milliamps.

Â Dependent sources have the little, the little tri, diamond shape.

Â Now the difference between the independent source and the dependent source is

Â that the independent source doesn't depend on the rest of the circuit.

Â It's going to be.

Â It's going to be independent, no matter what you do to the rest of the circuit,

Â you define a function for that independent source.

Â Now dependent source, there's a dependence on some other part of it.

Â For example, I might have this voltage supply, gives me a voltage, but

Â it might be dependent on current in one of my branches, or I might have.

Â A dependent current source which might be

Â dependent on a current in one of my branches.

Â It might be, be dependent on a voltage at one of my nodes.

Â So, these two are dependent on something else that's happening in the circuit.

Â This right here.

Â Is independent of what's going on in the circuit.

Â Now all of these, all voltage sources have the units of volts, and

Â all current sources have the unit of amps.

Â Let's look at a common, common connection here.

Â This is a, a circuit schematic.

Â We've got a independent.

Â Voltage source.

Â An independent currant source.

Â We've got our ground right here.

Â We've got our resistors.

Â This case, we don't have any capacitors or inductors.

Â We've got some nodes here.

Â These are all connected together.

Â That's one node.

Â That's another node.

Â Here's a node right here.

Â And then we've got some nodes that only connect to resistors.

Â So this resistor, this is a series combination because the resis,

Â they're connected right in the middle.

Â I don't see any other obvious connections.

Â These two are not series.

Â Because they're connected in the middle, but

Â they're also got something coming off of it.

Â So that means they're not in series.

Â And similarly, these for example, they're not in series nor are they in parallel.

Â To be in parallel, they'd have to be connected together at both ends.

Â So, this particular circuit, we show with this ground and

Â ground is very commonly shown in electronic circuits.

Â But they're shown oftentimes in a different way, they're shown this way

Â because every, everything along this bottom node is connected to ground.

Â So, I could just separate them out and

Â just show each point coming down to ground.

Â So this is equivalent, if I'm trying to do Kirchoff's Voltage Law or

Â Kirchoff's Current Law.

Â In this circuit versus this one, I'm going to treat this as if these are all

Â connected together with a line, just like this is.

Â So this lesson just gave some summary review of basic circuit components.

Â In the next lesson we will cover Kirchhoff's Laws.

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