The Theory Behind Electronics - A Beginners Guide

Starting our journey with a basic definition of Current, Voltage and Power.

Atoms (OMG!) are the building blocks of materials around use, Electric Charge is the amazing property of electrons and protons inside each atoms. Did you know that electric charge is holding the all universe from falling parts...... I am not kidding.... 

OK, but what is the relation to Current ? 

Current is the organized flow of free electrons in a closed loop, measured in Amperes. Current can be translated to other forms of energy like heat or light, making electric circuits extremely useful for end-less applications. 

Voltage is the potential electric motive force pushing the electrons in one direction, measured in volts.

As said by Bob Marley, "No Women No Cry...." --> in our case No Voltage No Current....

Power is the rate of energy being consumed in specific component and it is based on the amount of voltage drop and current flowing in that component. Power is measured using watts. To measure power consumption we need to add the time scale so in that case, power consumption is measured using Watts-Hours. In addition, to measure the energy capacity of some limited energy source like a battery we use Amperes-Hours.

Mind Mapping summary of this section. Please download also the mind mapping template file. 

To create voltage potential we need a power source, such a power source can be based on direct current or alternate current. But really, what's the different between them ? why do we need this AC power source if most of the things around us are working on DC ?

Direct Current is current that travels in one direction only, it is unidirectional with constant polarity. DC is very common method to operate low power digital circuit and devices so we will find it in almost electric circuit. 

Alternating Current is a type of power source that causes current to periodically change direction. AC today is the most common method to deliver electricity for long distance. The frequency of changing direction is measured in Hertz. 

AC today is the most common method to deliver electricity for long distances. But Why ? 

AC waveform is defined by frequency, amplitude and phase. 

It is TIME to understand the AC socket in our house, what is Hot, Neutral and the Ground wires ? 

To easily handle voltage, current and power in AC we used RMS (Root Mean Square ) values. 

Resistance, Capacitance, Inductance are the building blocks of almost any electric component, device or a circuit. We will find them everywhere...

Resistance is the property of a material, measured in ohms. What happens when some material resist to current flow ?    "I think it is getting HOT in here..."

Resistors devices are used to limit the current flow and set voltage levels across the circuits. 

So simple and so useful...

Let's start to use the Circuit Simulator ! 

How do we measure Current and Voltage strength in some location in our circuit ? 

Resistance, Capacitance, Inductance are the building blocks of almost any electric component, device or a circuit. We will find them everywhere...

Capacitance is a property of a body for storing energy in electric field, measured in farad. 

OK great, but for what ? 

Capacitors devices are used to store and release electric energy. 

Capacitors are charged and discharged in an exponential pattern (don't run away please...). So how can we calculate the specific TIME they will be charged/discharged ? what are the applications of capacitors ?

Time constant is the easiest parameter to handle capacitors charging and discharging time.

There are all sorts of capacitor types out there, each with certain features and drawbacks which make it better for some applications than others.

Capacitors are widely used as parts of electrical circuits:

• Blocking direct current while allowing alternating current to pass

•  Smooth current fluctuations for signal or control circuits

• Filter specific frequencies (e.g. radio)

• Generate signal waves used for timing

• And more….so commonly used that in almost every circuit we will find them pushing their big nose...

Let's see the MAGIC of charge of discharge. 

Electromagnetism = Electro + Magnetism

Magnets?!? , what are you talking about ?

Not easy but really interesting stuff !

Based on Electromagnetism, we can create magnetic field using current ? did you ever created Electromagnet as a kid ? 

What will happen when a current connected to a circuit with a wire coil, will vary on the time scale, like using AC signal as input ?

Self-inductance is how inductors store energy in magnetic field. 

Inductance is a property of an electrical conductor by which a change in current flowing through it induces an electromotive force. Inductance is measured in Henry.

In the preceding sections, we learned how to calculate the RC time constant for a resistor-capacitor circuit. A similar calculation can be done for inductors, except that instead of calling it the RC time constant, we call it the RL time constant. But the Idea is almost the same. 

Time-varying magnetic field (flux) induces an electromotive force in nearby conductors. The induced force is called Electromotive Force (EMF). A device specifically designed to produce the effect of mutual inductance between two or more coils is called a transformer. All our AC to DC converters are working based on this effect. 

Transformers, Electric Motor and AC Generator are based on the principle of inductance.

Let's see some simple example of Self-Inductance.

p.s. the circuit simulator is not smart enough to present mutual inductance....

Semi-conductors are the most important step in moving to digital electronics, as they are the building blocks for other more complicated components. 

Materials are classified by their ability to conduct electricity. Substances that easily pass an electric current, are referred to as conductors. Materials that have a difficult time passing an electric current are called insulators. A third category of material whose conductivity lies between those of conductors
and insulators. This third category of material is referred to as a semiconductor. 

Diode is simple application of Semi-Conductors while fusing together N-type and P-type semiconductor materials. Diode are basically a one way gate for current.

A transistor is like a diode with a additional third layer of either p-type or n-type semiconductors on one end. Two common types of transistors – PNP and NPN. Transistors are used to amplify electrical power or switch electronic signals.

First application of transistor is just as simple controlled SWITCH. 

Next applications is to create a digital logic gate ! all the chips the you see everywhere are based on such applications, just they are very, very, very small created during the chip production process. 

Give me some more power please...  that's another useful application of transistor, to amplify signals. 

Ohm’s Law and Kirchhoff's Laws are the basic laws of electric circuits helping to perform simple to complex circuit analysis.

We first defined some basic circuit topology – branch, node and loop and how to combine components in series and in parallel.

R, L, C components are commonly places in series and in parallel. Why ? many reasons and one of them is to create variety of values that we can't find off-the-shelf in the store. 

Ohm’s Law is used to define the relation between  Voltage, Current and Resistance. The electrical current (I) flowing through a fixed linear resistance is directly proportional to the Voltage applied across it (V).

KCL also called the junction rule saying that at any node (junction) in an electrical circuit, the sum of currents flowing into that node is equal to the sum of currents flowing out of that node.

KVL also called the closed loop rule saying that the algebraic sum of the voltages around any loop of a circuit is zero meaning the amount generated equal to the amount used.

All most finished !

Let's review the flow of topics and some key things to remember. 

Ok, what NEXT ?