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 behind at the electrical engineering and electronics, it is not an easy task but I will try, using and making available my long experience in the field.
Of course it is impossible to condense such a 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

We start from the raw material, that is, from 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 studied and defined it.

In defining the electric current we have introduced another primary parameter, the difference in electrical potential D.D.P. or electric voltage, or electric motor force F.E.M. that is, the force that creates the electrical imbalance in the atoms of a generic conductor, and therefore the circulation of electrons, which in an attempt to restore equilibrium create the aforementioned flow, it is measured in Volta, abbreviated as 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 electrical voltage, the continuous one which is constant (it does not vary over time), and the alternating one (it varies in value over time and can have both a positive and a negative sign).
Defined as the main architects of the entire electric world, a third force remains to be defined, we are talking about electrical resistivity, that is, of the force that hinders the movement of electrons in a generic conductor (link between electrons and the atom's nucleus), it is measured in Ohm, in honor of the German physicist Georg Ohm who studied and defined it, it is indicated with the omega Ω symbol.
The electric power is instead the work done by the current and the voltage to obtain a given purpose and is measured in W.

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

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 given 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 s eparata from the imaginary part by the letter Ι (iota).

There are materials that oppose the circulation of the current more than others, ie 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 specific resistivity low and hardly oppose the passage of electric current (copper, gold, silver, aluminum, brass, generally metallic materials).
There are also particular materials called semiconductors (germanium and silicon) which have a specific neutral resistivity, they use a procedure called "doping" to form the basis for obtaining the transistors and integrated circuits that we will see later.

But how is electricity produced? The simplest generator is the electric battery, which produces a continuous type voltage and is formed by disks of different conductive material superimposed and immersed in an electrolyte. Currently, rechargeable batteries can also be supplied to correctly call "electric accumulators" which, after a recharge procedure, return at a later date the accumulated energy.
For small capacities, nickel-cadmium accumulators are used, or the perfected nickel-manganese type, for large capacities lead-acid accumulators are used, each having positive and negative aspects.

The electric energy that arrives in our homes is of alternating type, and is produced from renewable sources, that is that they are regenerated in a short time (photovoltaic panels, biomass, hydroelectric, wind power plants) 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 or else into electricity, or from mechanical energy, through a machine called an alternator, which works on the principle of electromagnetic induction.
The energy is then distributed as shown in the figure below.
             
               

To conclude, I quote the formulas to calculate at least the main parameters exposed before, ie voltage, current and resistance, to do this we are helped by the "Ohm's law" which allows 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 that we pass 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 substance, W = V * I

By clicking on this text you can download an XLS file that I created specifically with which you can calculate all the parameters required by the "Ohm law".

              
                  Wind farm with wind generators.                   Solar farm with photovoltaic panels

                            220 KV power line                              Transformer and distribution substation

                                       Electronics

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 in the case of some radio frequency circuits and some low frequency.

Instead 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 (electrical 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.