Electronics, appliances, circuits and various applications

Electronics The term e. was introduced around 1940 to indicate that part of electrical science dedicated to the study of phenomena associated with the motion of electron beams in vacuum and gases ( American standard definition of electrical terms, 1941).

The definition of e. it also included the various devices, circuits and applications based on these phenomena and, in particular, the vacuum and gas pipes and many of the circuit devices used in radio engineering and telephone transmission systems.

Since in all these cases the intensities of the electric currents and the power levels were far lower than those used in traditional electrical engineering, the term ‘weak current technique’ was also used as a synonym for e., As opposed to ‘current technique strong ‘as a synonym of electrical engineering.

From 1940 onwards, the panorama of devices, applications and the same physical phenomena of electronic interest has increased so rapidly that the original definition was completely inadequate. The progress of e. they can be classified into three categories:

  • introduction and development of solid-state devices with consequent miniaturization of electronic components;
  • development of devices and apparatuses at ever higher frequencies, up to microwaves and optical devices;
  • the extraordinary increase in the complexity of the devices and possible applications. Consequently, the identification of e. with the technique of weak currents, if we also take into account the fact that there is a part of E, called industrial electronics, which deals with a large class of electronic devices for medium and high powers.


The beginnings of electronics

With the discovery of the electron ( JJ Thomson, 1897), as the essential component of matter and ‘how much’ of electricity, the first phase of the history of e begins. properly so-called.

In the same year, the first cathode ray tube was created by F. Braun, which is the progenitor of the display devices used in oscilloscopes, televisions and computer terminals.

In the following years, the process of electron emission from heated metals (thermoelectric emission) was clarified and set in quantitative terms by OW Richardson.

In 1902 JA Fleming created the vacuum diode, which is the fundamental component for transforming a bidirectional current into a unidirectional one. A decisive step in the development of e. occurred in 1906 when L. De Foresthe managed to insert a third grid-shaped electrode into the diode in order to control the flow of electrons between the two main electrodes, thus creating the triode.

With this component it was possible to make for the first time a device equipped with amplification, that is, capable of obtaining an amplified copy of the electrical signal present at the input. Various electron tubes with multiple electrodes followed the triode.

The electronic tubes became the essential components in the realization of telecommunication apparatuses and systems (long-distance telephony, radiocommunications, etc.) and in various other applications. Further progress was made with the creation of the first bistable circuits, with which the field of digital electronics was opened and the possibility of storing information in electronic circuits was shown; these circuits represented the basis of the subsequent realizations of the first digital processors.


Before and during the Second World War research in the field of e. they aimed to create electronic tubes for high frequencies and, secondly, to replace electronic tubes with solid-state devices. The first field of studies gave rise, during the Second World War, to the realization of the magnetron which represented the first electronic tube to generate high power electrical signals in the microwave field. This component, which was followed by a large class of similar devices, allowed the invention and development of the radar. of strategic interest in the context of the conflict.

The second field of research allowed the realization of the transistor by W. Shockley, J. Bardeen and WH Brattain (1947). This component laid the foundations of solid-state electronics and produced a real revolution. itself, so as to make most of the circuits and devices previously made obsolete. The first pointed transistor (because it was made by point contacts placed at close distance on a germanium plate) was successively overcome by the junction transistor (1951), much more stable and reliable. This invention was followed, in a few years, by the introduction of an extensive variety of solid-state electronic devices (diodes of various types, photovoltaic components, particle detector diodes, thyristors, field-effect transistors, etc.).

From the mid-1950s, the ‘transistorization’ of e. Applications began. (the first transistor radio dates back to 1954, the first transistor calculator to 1957). Subsequently, a new revolution. it was accomplished with the construction of integrated circuits, the first of which was made in the laboratories of the texas instruments in 1958. It was an inevitable consequence of the invention of the transistor, which made it possible to create an entire circuit inside a tiny plate of semiconductor material.

The integration of electronic apparatuses appeared immediately advantageous and such as to make once again most of the previous devices outdated.

The advantages achieved have been innumerable, from the possibility of miniaturization to the greater frequency of use, to the increase in reliability (that is, the possibility of correct operation in long periods of time). Then there is the improvement of the operating speed of digital devices, up to obtain switching times of the order of nanoseconds. Finally, another very important advantage concerns the strong reduction in manufacturing costs.


This has allowed the development of a new part of E., known by the name of microelectronics.

The progress made subsequently mainly concerned the growing complexity of the integrated circuits, identifiable with the number of components that can be made on the same silicon plate (chip) and the improvement of the performance of the devices.

Integrated circuits have been developed which contain over one million transistors in the area of ​​a few square millimeters (VLSI, very large scale integration).

Among the most common integrated circuits are ultra-high-density memories, which store data in the digital form up to several billion bits and the so-called microcomputers, which make a complete computer of its main parts in a single chip.

Other innovative electronic devices concerned the applications of superconductivity and the Josephson effect.

This effect allows the creation of amplifiers for extremely low input signals and logic circuits at very high speed, with very low power consumption.

Parallel to the development of integrated electronics, the foundations of optoelectronics have been laid, founded on the use of lasers, optical fibers and a wide range of optical components.

The development of such devices finds wide applications in various fields, among which that of telecommunications.


The most important distinction that can be made is that between analog electronics and digital (or numerical ) electronics, although this tends to fade in the hardware design phases, as each digital circuit must be designed and verified on analog bases, considering the evolution of electrical quantities continuously over time.

This distinction is also overcome in some types of computers that use hybrid circuits, that is, containing an analog and a digital part, as happens in the case of neural networks.

Analog electronics

L’e. analog deals with circuits and devices in which the various signals can take on a continuous set of values. The study of analog electronic circuits is addressed by means of the methodologies of the theory of electrical networks.

It is typical of e. the consideration of active circuits, in which transistors are present. In the case of passive circuits, that is, containing only resistors, capacitors and inductors, the terms electric circuit or electronic circuit are substantially equivalent.

uses the methods of electromagnetism in all problems involving aspects of propagation of electromagnetic waves or circuits at very high frequencies (microwaves or millimeter waves ).

Digital electronics

Digital deals with circuits and devices in which the various signals can only take on a discrete set of values ​​( typically two values). In this case the e. it borders on computer science, digital processes signals that can be identified with logical variables.

The various logic circuits, which can be made according to different techniques, are grouped into logical families which are distinguished on the basis of the technology used for the construction of the elementary cells (logic gates), the power consumption and the switching speed.

Logical families are identified with abbreviations (TTL, NMOS, CMOSetc.). From the IT point of view, the electronic devices and architectures used in the creation of computing devices are indicated with the term hardware, as opposed to the programming methodologies, known with the term software.

It is evident that the hardware is based on the type of technology adopted and that the modification of a computer’s hardware represents a radical change in the characteristics of the machine compared to a modification in the software.

Power electronics

Denomination introduced in the 1980s and established internationally in the 1990s, to indicate that part and e. which treats electronic components with non-low voltage and/or with high operating current, and studies the schemes, equipment, and systems that use them in order to convert electrical energy so as to supply loads in an optimal manner in relation to their type of operation. The denomination, sometimes used as opposed to signal electronics, highlights that the characterizing aspect is the high level of the converted power and also that the aforementioned equipment is used in the sector of distribution and use of electricity. Sometimes it is confused and superimposed with industrial electronics, which includes wider application sectors.

The great diffusion of e. of power and the consequent introduction of the denomination took place following the construction and development of semiconductor devices, such as the thyristor (also called SCR), the GTO, the bipolar power transistors, the IGBT, power MOSFETs, etc .; in almost all cases these devices are used in the saturation zone, or as controlled switches.

The most important application sectors include: variable speed drives in industry and for vehicle traction; power supplies and in particular static uninterruptible power supplies; the large converters (rectifier and inverters) for direct current electricity transmission systems.

From a scientific and technological point of view, e. power is now to be considered mature and autonomous in terms of both teachings in the university and research programs. The problems that most characterize e. of power, in addition to the aspects of analysis similar to those of e. traditional, concern power flows and therefore performance problems, protections from voltage gradients and overcurrents, cooling modes and problems of induced disturbances.


The electronics industry recorded huge increases in terms of turnover in the 1990s, a consequence of the ever-wider range of products and significant progress in their characteristics.

In fact, the use and diffusion of electronic techniques have assumed an increasingly important role in relation to other industrial sectors, and more generally in the economic progress of modern society.

in the fields of telecommunications, automation and information technology. Among the causes that have determined the strong expansion of the sector, in addition to technological advances and new components with increasingly advanced features, the continuous decrease in the cost-performance ratio of products that use electronic components assumes fundamental importance.

The use of highly concentrated integrated circuits, a fundamental aspect in the development of information technology, has rapidly expanded to the telecommunications and automation sectors, now becoming widely associated with digital techniques. To these sectors must be added those of electronic office and home equipment, instrumentation and systems measurement, and control of electromedical instruments and special devices.

The main countries producing electronic components worldwide are the USA, Japan, and South Korea. Europe is present with two important semiconductor companies: the Franco-Italian STMicroelectronics and the Dutch NXP (the independent company founded by Philips Semiconductor).

As far as the Italian electronics industry is concerned, the dependence from abroad for the supply of active and passive components (especially the most valuable ones) is high.

Electronic music

Type of musical expression in which the composer creates sounds from their constituent elements and then manipulates them with the instruments of electroacoustics and sound recording. The beginning of research on the new possibilities offered by.

the musical creation took place with the establishment, in Cologne in 1951, of the Studio für Elektronische Musik directed by Eimert. He was then joined by several musicians such as Stockhausen, Pousseur, Evangelisti.


In imitation of the Cologne study, similar centers sprang up in various countries: in Gravesano, in canton Ticino, the UNESCO Electroacoustic Experimental Study was founded in 1955 under the direction of Scherchen; in Milan, in 1956 the Musical Phonology Studio was established, of which Berio and Maderna were the animators. Among the most important developments of the 1980s and 1990s, a significant role lies with the numerous applications of information technology to musical and musicological work.

The development of audio-digital technologies, in addition to allowing the close interaction between sound and visual media, which gave rise to the wide range of multimedia works, has helped to release the execution of music. from the mere reproduction of the magnetic tape: more and more often the interpretation takes place to live, both as live electronics, both as real-time manipulation of the sound of traditional instruments.


Related Articles

Leave a Reply

Your email address will not be published. Required fields are marked *