Welcome to my web page dedicated to electronics and electrical engineering.

On this page I will try to define in simple words the immense world that lies behind electrical engineering and electronics, it is not an easy task but I will try, making available my long experience in the field. Of course it is impossible to condense a very vast subject in this small text, but if you intend to deepen or need professional advice, you can contact me via the Contact page. At the end of this document you will find links to the in-depth pages dedicated to active and passive electronic components.

                                                                      Electrical engineering

Let's start with the raw material, that is, what we need to make everything work, we are talking about electric current.

The classic definition is, "a flow of electrons circulating in a conductor subjected to a potential difference or electrical imbalance", the unit of measurement is the Ampere, abbreviated with a capital A, in honor of the French physicist Andrè Marie Ampère who he studied it and defined it. In the definition of the electric current we have introduced another primary parameter, the difference in electric potential  or electric voltage, or electromotive force, that is the force that creates the electrical imbalance in the atoms of a generic conductor, and therefore the circulation of the electrons, which in the attempt to re-establish the equilibrium create the flow of electrons mentioned above, it is measured in Volta, abbreviated in Volt and indicated with a capital V, all this in honor of the illustrious Italian scientist Alessandro Volta, who carried out many studies and created the first voltage generator in the world (the Volta electric battery), there are two types of electric voltage, the continuous one which it is constant (it does not vary in value over time in a regular way) and can have a positive or negative sign, and the alternating one (varies in value over time in a regular way and can have both positive and negative signs).

Having defined the main architects of the whole electrical world, a third force remains to be defined, we are talking about electrical resistivity, that is, the force that hinders the movement of electrons in a generic conductor (bond between electrons and nucleus of the atom), it is measured in Ohm, in honor of the German physicist Georg Ohm who studied and defined it, it is indicated with the symbol omega Ω. Electric power, on the other hand, is the work done by current and voltage to achieve a given purpose and is measured in Watts, symbol W.

From what has been said it is clear that applying an electric voltage (V) to a generic conductor causes a flow of electrons (A), however hindered by the intrinsic resistivity (Ω) to the conductor itself to be crossed by the current.

This can be said when working in direct currents (constant value over time and of non-variable polarity), in alternating current (variable value and polarity that changes between positive and negative) various other non-negligible parameters intervene which must necessarily be taken into account, they are the frequency f (how many times a certain current passes through zero in the unit of time (1 second), the period S (the inverse of the frequency) the capacitive reactance Xc (capacitor), the inductive reactance Xl (inductor) and the phase shift φ (fi), these quantities combined with the resistance create another equivalent quantity (i.e. born from the combination of all the parameters) called impedance and indicated with the capital Z symbol, besides the alternating current (used in sinusoidal form) must be represented in vector form, and therefore being a mixed quantity it has a real part and an imaginary part, the imaginary part is in the formulas if parade from the imaginary part by the letter Ι (iota).

This is a very large chapter and cannot be dealt with here, otherwise the web page would take on gigantic dimensions and complicate things too much for those who are now approaching the subject, for further information you can use this page in the link or contact me by going to the Contacts page.

There are materials that oppose the circulation of the current more than others, that is, they have a higher specific resistivity, they are the insulators (rubber, glass, PVC, dry wood, plastic, distilled water), otherwise the conductive materials have a very low specific resistivity  and have little opposition to the passage of electric current (copper, gold, silver, aluminum, brass, generally metallic materials). All this is due, as mentioned before, to the specific resistivity (symbol ρ) typical of each material, which can be defined as the bond between electrons and a more or less strong nucleus, which opposes the movement of electrons from one atom to another.

There are also particular materials called semiconductors (germanium and silicon) which have a specific neutral resistivity, they, through a process called "doping", form the basis for obtaining the transistors and integrated circuits that we will discuss later in the active components page.

But how is electrical voltage produced? The simplest generator is the electric battery, it produces a continuous voltage and is formed by disks of different conductive material (galvanic effect) superimposed and immersed in an electrolyte, for further information you can go to the following link.

At present, rechargeable batteries are also available, to be correctly called "electric accumulators" which, after a recharging procedure, subsequently return the accumulated energy in a variable percentage depending on the type of technology used. For small capacities nickel-cadmium accumulators are used or the improved nickel-manganese type, for large capacities lead-acid accumulators are used, or lithium ion accumulators each has positive and negative aspects, to learn more click on this link .

The electricity that arrives in our homes is of the alternating and sinusoidal type, and can be produced from renewable sources, i.e. that are regenerated in a short time (photovoltaic panels, biomass power plants, hydroelectric, wind, geothermal) or from non-renewable sources. (oil, coal, methane, nuclear), however almost all of it is obtained by converting an energy that can be solar, nuclear, geothermal or other into electrical energy through a machine called alternator, which works according to the principle of electromagnetic induction, you can learn more by going to this link.

The energy is then distributed as indicated in the figure below.

To conclude, I quote the formulas for calculating at least the main parameters mentioned above, ie voltage, current and resistance, to do this we are helped by the "Ohm's law" which allows us to calculate one of the parameters knowing the other two. by convention the voltage is indicated with V, the current with I and the resistance with R, having said this let's move on to the formulas:

Voltage V = R * I    Current I = V / R    Resistance R = V / I.

the value of the electric power is instead given by the multiplication between the voltage and the current, in essence, W = V * I.

By clicking on this text you can download a file in XLSX format to calculate all the parameters of Ohm's law.

                              Wind farm with wind generators.                                                                                                                                  Solar farm with photovoltaic panels

                                                 220 KV power line                                                                                                                                               Transformer and distribution substation

                                                                                      Electronic

After having clarified what electric current is, how it is produced and distributed up to our homes and how to calculate its main parameters, we can now devote ourselves to the more refined aspect, that is to the actual electronics, but what is the electronics?
It can be defined simply as the science that uses electrical voltages and currents (low power electrical signals) to create and operate instruments, which use "signals" to condition and process other physical quantities.
The aforementioned electronic instruments are formed by "electronic circuits" in turn formed by passive and active components, which are assembled and connected to each other in order to achieve the purpose set in the design phase.

Electronics is further divided into two major sectors, Analog Electronics and Digital Electronics.

Analogue electronics are those where electronic circuits process electrical signals that can have any voltage value from zero to infinity at any time, for example analog amplifier circuits with operating class A-AB-C or circuits fall within this branch. radio frequency.

On the other hand, digital electronics can be defined as the one where logic signals are processed, that is, whose values can be only two, 0 or off, or 1 or on (true or false, Boolean logic), all of which fall into this now dominant sector. equipment processing logic signals, such as personal computers, smartphones, heat engine control units, etc. However, analog signals can also be processed by converting them into digital by means of special electronic circuits (A / D converters).

The main components used in electronics are the active and the passive ones, the passive components are those that use energy but do not carry out signal amplification or production or processing, they serve as a contour to the active ones to polarize them and make them work, on the contrary the active components are those which can produce, amplify or process signals.

The active and passive components are dealt with on separate pages, you will find the links to access them at the end of this page.

In both electrical engineering and electronics, in order to understand the operation of a given circuit, the operating scheme is necessary, which can be both electrical and practical. The electrical or theoretical one uses standardized symbols to represent the components used and serves to facilitate understanding of the operation, while the practical one represents the construction diagram of the circuit.
At this link you will find some symbols used in the wiring diagrams.

                                             Digital electronic circuit                                                                                                                  Digital electronic circuit with SMD components and PCI interface bus

Of course it is impossible to condense all these concepts in a small space, mine is just a good guide for those who are looking into this fantastic world, it is still possible to deepen or request professional advice by contacting me, for this go to the contact page.

Thank you for visiting my website and following my guide, please come back and visit it.

                                       Passive components                                   Active components