Electronics

Electronic circuit on a plate for prototypes or protoboard.

Details of an integrated SMD circuit.

Electronics is a branch of applied physics comprising the physics, engineering, technology, and applications that deal with the emission, flow, and control of electrons or other charged particles electrically—in vacuum and matter. The identification of the electron in 1897, together with the invention of the vacuum tube, which could amplify and rectify small electrical signals, launched the field of electronics and the age of the electron.

Electronics deals with electrical circuits involving active electrical components such as vacuum tubes, transistors, diodes, integrated circuits, optoelectronics, and sensors, associated with passive electrical components and interconnection technologies. Electronic devices generally contain circuitry that consists primarily, or exclusively, of active semiconductors supplemented by passive elements; such a circuit is described as an electronic circuit.

The non-linear behavior of active components and their ability to control electron flows makes it possible to amplify weak signals. Electronics are widely used in data processing, telecommunications, and signal processing. The ability of electronic devices to act like switches makes the digital processing of information possible. Interconnection technologies, such as printed circuits, electronic packaging technology, and various other forms of communication infrastructures, complete the functionality of the circuit and transform the mixed electronic components into a regular working system, called an electronic system; Examples are computers or control systems. An electronic system can be a stand-alone device or a component of another designed system.

Electrical and electromechanical science and technology is concerned with the generation, distribution, switching, storage, and conversion of electrical energy to and from other forms of energy (using cables, motors, generators, batteries, switches, relays, transformers, resistors and other passive components). This distinction began around 1906 with Lee De Forest's invention of the triode, which made electrical amplification of weak radio signals and audio signals possible with a non-mechanical device. Until 1950, this field was called "radio technology" because its primary application was the design and theory of radio transmitters, receivers, and vacuum tubes.

Today, most electronic devices use semiconductor components to control the electrons. The study of semiconductor devices and related technology is considered a branch of solid-state physics, while the design and construction of electronic circuits to solve practical problems is the concern of electronic engineering. This article focuses on the engineering aspects of electronics.

The branches of electronics

Electronics has the following branches:

History

Printed circuit card

Edison was the first to observe the thermionic emission or Edison effect in 1883, by placing a sheet inside a light bulb to prevent the blackening that the carbon filament produced in the glass bulb. When the metal foil was positively biased with respect to the filament, a small current was produced between the filament and the foil. This fact occurred because the electrons of the atoms of the filament, upon receiving a large amount of energy in the form of heat, escaped from the attraction of the nucleus (thermionic emission) and, crossing the empty space inside the bulb, were attracted by the positive polarity of the sheet.

The British engineer Sir John Ambrose Fleming (1849-1945) applied the Edison effect to a tube to detect Hertzian waves and thus invented the diode, the first electronic tube in which a vacuum had been created and inside which existed an anode (positive electrode) and a cathode (negative electrode). Upon reaching the state of incandescence, the cathode emitted negatively charged electrons that were attracted to the anode; that is, the diode acted as a valve that only allowed current to pass in one direction.

The other big step was taken by Lee De Forest when he invented the triode in 1906. This device is basically like the vacuum diode, but a control grid was added between the cathode and the plate, in order to modify the electron cloud of the cathode, thus varying the plate current. This was a very important step for the manufacture of the first sound amplifiers, radio receivers, televisions, etc.

Lee De Forest is considered the "father of electronics", since before the triode, only alternating current could be converted into direct or direct current, that is, only power supplies were built, but with the creation of the vacuum triode, came the amplification of all kinds of signals, especially audio, radio, TV and everything else, this caused the industry of these equipment to have such a big rebound that it already for the decades superior to 1930 the word of "electronics" to refer to the technology of these emerging equipment.

As time passed, vacuum tubes were perfected and improved, appearing other types, such as tetrodes (four-electrode tubes), pentodes (five electrodes), other tubes for high-power applications, etc. Within the improvements of the valves was their miniaturization.

But it was definitely with the transistor, introduced by Bardeen and Brattain of the Bell Telephone Company, in 1948, that further miniaturization of devices such as radios was allowed. The junction transistor appeared somewhat later, in 1949. This is the device used today for most electronics applications. Its advantages with respect to valves are, among others: smaller size and fragility, greater energy efficiency, lower supply voltages, etc. The transistor does not work in a vacuum like tubes, but in a solid state semiconductor (silicon), which is why it does not need hundreds of volts to work. Despite the spread of semiconductors, tubes are still used in small audiophile circles, because they are one of their most widespread myths.

The transistor has three terminals (the emitter, the base, and the collector) and resembles a triode: the base would be the control grid, the emitter the cathode, and the collector the plate. By properly polarizing these three terminals, it is possible to control a large collector current from a small base current.

In 1958 the first integrated circuit was developed, which housed six transistors on a single chip. The first microprocessor, the Intel 4004, was developed in 1970. At present, the fields of development of electronics are so vast that it has been divided into several specialized disciplines. The biggest division is the one that distinguishes analog electronics from digital electronics.

Electronics is, therefore, one of the branches of engineering with the greatest projection in the future, along with computing.

Electronics applications

Electronics currently performs a wide variety of tasks. The main uses of electronic circuits are the control, processing, distribution of information, conversion and distribution of electrical energy. These uses involve the creation or detection of electromagnetic fields and electrical currents. Then it can be said that electronics generally covers the following application areas:

• Electronic control
• Telecommunications
• Power Electronics

Electronic systems

An electronic system is a set of circuits that interact with each other to obtain a result. One way to understand electronic systems is to divide them into the following parts:

1. Tickets or Inputs – Electronic or mechanical sensors (or transducers) taking the signals (in the form of temperature, pressure, etc.) of the physical world and making them signals of current or voltage. Example: Thermocouple, photoresistance to measure the intensity of light, etc.
2. Signal Processing Circuits – They consist of electronic devices connected together to manipulate, interpret and transform voltage and current signals from transducers.
3. Departures or Outputs – Actuators or other devices (also transducers) that convert current or voltage signals into physically useful signals. For example: display to register the temperature, a focus or system of lights that are automatically turned on when it is darkening.

Basically there are three stages: The first (transducer), the second (processor circuit) and the third (actuator circuit).

As an example let's assume a television. Its input is a broadcast signal received by an antenna or by a cable. Signal processing circuitry inside the TV extracts information about brightness, color, and sound from this signal. The output devices are a cathode ray tube or LCD monitor that converts electronic signals into images visible on a screen and speakers.

Another example can be that of a circuit that reveals the temperature of a process, the transducer can be a thermocouple, the processing circuit is responsible for converting the input signal into a voltage level (voltage comparator or window) at an appropriate level and send the information decoding it to a display where it gives us the real temperature and if it exceeds a preprogrammed limit, activate an alarm system (actuator circuit) to take the pertinent measures.

Electrical signals

It is the representation of a physical phenomenon or material state through an established relationship; the inputs and outputs of an electronic system will be variable signals among themselves.

In electronics we work with variables that take the form of voltage or current, these can be called signals. Signals can primarily be of two types:

• Variable analog– These are those that can take an infinite number of values between two limits. Most phenomena of real life give signs of this type (pressure, temperature, etc.).
• Digital variable- Also called discrete variables, understood by these, the variables that can take a finite number of values. Because physical components with two different states are easily realized, this is the number of values used for these variables, which are therefore binary. Being these variables easier to treat (in logic they would be the V and F values) are those that are usually used to relate several variables between themselves and their previous states.

Voltage

It is the potential difference generated between the ends of an electrical component or device. We can also say that it is the energy capable of moving the free electrons of a conductor or semiconductor. The unit of this parameter is the volt (V). There are two types of voltage: direct and alternating.

• Continuous voltage (VDC)– It is the one who has a defined polarity, such as the one that provides batteries, batteries and power supplies.
• Alternate voltage (ACV)– It is the one whose polarity is changing or alternating over time. The most common alternate voltage sources are generators and domestic energy networks.

Electric current

It is the flow of free electrons through a conductor or semiconductor in one direction. The unit of measure for this parameter is the ampere (A). Just as there are direct or alternating voltages, currents can also be direct or alternating, depending on the type of voltage that is used to generate these current flows.

Stamina

It is the physical property by which materials tend to oppose the flow of current. The unit of this parameter is the ohm (Ω). The inverse property is electrical conductance.

Electronic circuits

An electronic circuit is called a series of electrical elements or components (such as resistors, inductances, capacitors, and sources) or electronics, electrically connected to each other for the purpose of generating, transporting, or modifying electronic signals. Electronic or electrical circuits can be classified in several ways:

Analog Circuits

Hitachi J100 adjustable frequency drive chassis

Most analog electronics, such as radio receivers, are built from combinations of a few basic types of circuits. Analog circuits use a continuous range of voltage or current instead of discrete levels as in digital circuits.

The number of different analog circuits that have been devised so far is enormous, especially since a "circuit" It can be defined as anything from a single component to systems containing thousands of components.

Analog circuits are sometimes called linear circuits although many non-linear effects are used in analog circuits, such as mixers, modulators, etc. Some good examples of analog circuits are transistor and vacuum tube amplifiers, operational amplifiers, and oscillators.

Modern circuits that are fully analog are rarely found. Today, analog circuits can use digital or even microprocessor techniques to improve their performance. This type of circuit is often called a "mixed-signal" instead of analog or digital.

Sometimes it can be difficult to tell the difference between analog and digital circuits, as they have both linear and non-linear operating elements. An example is the comparator, which receives a continuous range of voltage but only outputs one of the two levels of a digital circuit. Similarly, an overdriven transistor amplifier can take on the characteristics of a controlled switch that has essentially two output levels. In fact, many digital circuits are implemented as variations of analog circuits similar to this example...after all, all aspects of the real physical world are essentially analog, so digital effects are only realized by constraining analog behavior.

Digital Circuits

Digital circuits are electrical circuits based on a number of discrete voltage levels. Digital circuits are the most common physical representation of Boolean algebra, and are the basis of all digital computers. For most engineers, the terms "digital circuit", "digital system" and "logic" they are interchangeable in the context of digital circuitry. Most digital circuits use a binary system with two voltage levels called "0" and "1". Often the "0" logic is a lower voltage and is called "Low", while the "1" logical is named "Stop". However, some systems use the reverse definition ("0" is "High") or are current based. Often the designer of the logic can reverse these definitions from one circuit to another, at his convenience to facilitate his design. Defining levels as "0" or "1" it is arbitrary.

Ternary logic (with three states) (with three states) logic has been studied, and some prototype computers have been made.

Computers, electronic clocks, and programmable logic controllers, used to control industrial processes, are built with digital circuitry. Digital Signal Processors are another example.

Heat dissipation and thermal management

Heat generated by electronic circuitry must be dissipated to prevent immediate failure and improve long-term reliability. Heat dissipation is mainly achieved by passive conduction/convection. Means of achieving higher dissipation include heat sink and fans for air cooling, and other forms of computer cooling such as liquid cooling. These techniques use convection, conduction, and radiation of thermal energy.

Noise

Electronic noise is defined as "unwanted disturbances superimposed on a useful signal that tend to obscure its informational content." Noise is not the same as signal distortion caused by a circuit. Noise is associated with all electronic circuits. Noise can be generated electromagnetically or thermally, which can be decreased by lowering the operating temperature of the circuit. Other types of noise, such as shot noise, cannot be removed, as they are due to physical property limitations.

Theory of electronics

Mathematical methods are an integral part of the study of electronics. In order to become proficient in electronics, it is also necessary to master the mathematics of circuit analysis.

Circuit analysis is the study of methods of solving generally linear systems for unknown variables, such as the voltage at a given node or the current through a given network path. A common analytical tool for this is the SPICE circuit simulator.

It is also important for electronics to study and understand the theory of the electromagnetic field.

Electronics Laboratory

Due to the complex nature of electronics theory, laboratory experimentation is an important part of developing electronic devices. These experiments are used to test or verify the engineer's design and detect errors. Historically, electronics labs have consisted of electronic devices and equipment located in a physical space, although in more recent years the trend has been toward electronics lab simulation software, such as CircuitLogix, Multisim, and PSpice.

Computer Aided Design (CAD)

Today's electronics engineers have the ability to design circuits using pre-made building blocks such as power supplies, semiconductors (ie semiconductor devices such as transistors), and integrated circuits. Electronic design automation software programs include schematic capture programs and printed circuit board design programs. The most popular names in the world of EDA software are NI Multisim, Cadence (ORCAD), EAGLE PCB and Schematic, Mentor (PADS PCB and LOGIC Schematic), Altium (Protel), LabCentre Electronics (Proteus), gEDA, KiCad and many others..

Packaging methods

Over the years many different methods have been used to connect components together. For example, early electronics often used point-to-point wiring with components attached to wooden boards to build circuits. Other methods used were Cordwood construction and wire wrap. Today, most electronics use printed circuit boards made of materials such as FR4, or the cheaper (and less resistant) Synthetic Resin Bonded Paper (SRBP, also known as Paxoline/Paxolin (trade names) and FR2), characterized by its brown color. Concern for health and the environment in relation to the assembly of electronic products has increased in recent years, especially in the case of products destined for the European Union.

Design of electronic systems

Electronic systems design addresses the cross-disciplinary design issues of complex electronic devices and systems, such as mobile phones and computers. The subject covers a wide spectrum, from the design and development of an electronic system to ensuring its proper functioning, useful life and recycling. Electronic system design is, therefore, the process of defining and developing electronic devices. complex to meet specified user requirements.

Components

For the synthesis of electronic circuits, electronic components and electronic instruments are used. Below is a list of the most important components and instruments in electronics, followed by their most common use:

• Speaker: Sound playback.
• Cable: electricity driving.
• Switch: relay an entry to a chosen output between two or more.
• Switch: opening or closing of circuits, manually.
• Pill or battery: electric power accumulator.
• Transducer: transformation of a physical magnitude into an electric one.
• Viewer: data sample or images.

Analog devices (some examples)

• Operational amplifier: amplification, regulation, signal conversion, switching.
• Capacitor: energy storage, filtering, impedance adaptation.
• Diode: signal rectification, regulation, voltage multiplier.
• Diodo Zener: tension regulation.
• Inducer: adaptation of impedances.
• Potentometer: variation of electric current or voltage.
• Relay: opening or closing of circuits using control signals.
• Resistor: division of intensity or tension, limitation of intensity.
• Transistor: amplification, switching.

Digital devices

• Bistable: control of sequential systems.
• Memory: digital data storage.
• Microcontroller: digital system control.
• Logic computer: control of combination systems.

Power devices

• DIAC: power control.
• Fusible: protection against over-currents.
• Tiristor: semiconductor switch for power control.
• Transformer: elevate or decrease voltages, currents, and apparent impedance.
• Silicon controlled counter (SCR).
• Triac: power control.
• Varistor: protection against envelopes.

Measuring equipment

Electronics measurement equipment is used to create stimuli and measure the behavior of devices under test (DUTs). The measurement of mechanical, thermal, electrical and chemical magnitudes is carried out using devices called sensors and transducers. The sensor is sensitive to changes in the quantity to be measured, such as a temperature, a position or a chemical concentration. The transducer converts these measurements into electrical signals, which can feed instruments for reading, recording or controlling the measured quantities. Sensors and transducers can work in locations remote from the observer, as well as in environments that are unsuitable or impractical for humans.

Some devices act simultaneously as a sensor and transducer. A thermocouple consists of two junctions of different metals that generate a small voltage that depends on the differential term between the junctions. The thermistor is a special resistor, the resistance value of which varies depending on the temperature. A variable rheostat can convert mechanical movement into an electrical signal. Specially designed capacitors are used to measure distances, and photocells are used to detect light. Other types of devices are used to measure velocities, acceleration or liquid flows. In most cases, the electrical signal is weak and must be amplified by an electronic circuit. Below is a list of the most important measuring equipment:

• Galvanometer: measures the change of a certain magnitude, such as current intensity or voltage (or voltage). It is used in the construction of analog Amperimeters and Voltimeters.
• Amperimeter and amperimetric clamp: measure electrical current intensity.
• Wheatstone oximeter or bridge: measure electrical resistance. When the electrical resistance is very high (over the 1 MΩ) an insulation meter or meter is used.
• Voltmeter: measure the tension.
• Finemeter or polmeter: measures the three quantities mentioned above, in addition to electrical continuity and the B value of the transistors (both PNP and NPN).
• Vatmeter: measure electrical power. It is composed of an amperimeter and a voltmeter. Depending on the connection configuration you can deliver different electrical power measurements, such as active power or reactive power.
• Oscilloscope: measure the change of current and voltage over time.
• Logical analyzer: digital circuit test.
• Spectrator: measure the spectral energy of the signals.
• Signal vector analyzer: like the spectral analyzer but with more digital demodulation functions.
• Electrometer: measure the electric charge.
• Frequency or frequency counter: measure frequency.
• Time Domain Reflectometer (TDR): Test the integrity of long cables.
• Layer: measure electrical capacity or training.
• Electric counter: measure electrical power. Like the vatmeter, it can be configured to measure active (consumed) energy or reactive energy.

Theory of electronics

• Digital circuits
• Analog electronics