electronics

1. (used with a sing. verb) The science and technology of electronic phenomena.
2. (used with a pl. verb) Electronic devices and systems: The electronics aboard the new aircraft are very sophisticated.

For more information on electronics, visit Britannica.com.

Technology involving the manipulation of voltages and electric currents through the use of various devices for the purpose of performing some useful action. This large field is generally divided into two primary areas, analog electronics and digital electronics.

Analog electronics

Historically, analog electronics was used in large part because of the ease with which circuits could be implemented with analog devices. However, as signals have become more complex, and the ability to fabricate extremely complex digital circuits has increased, the disadvantages of analog electronics have increased in importance, while the importance of simplicity has declined.

In analog electronics, the signals to be manipulated take the form of continuous currents or voltages. The information in the signal is carried by the value of the current or voltage at a particular time t. Some examples of analog electronic signals are amplitude-modulated (AM) and frequency-modulated (FM) radio broadcast signals, thermocouple temperature data signals, and standard audio cassette recording signals. In each of these cases, analog electronic devices and circuits can be used to render the signals intelligible.

Commonly required manipulations include amplification, rectification, and conversion to a nonelectronic signal. Amplification is required when the strength of a signal of interest is not sufficient to perform the task that the signal is required to do. However, the amplification process suffers from the two primary disadvantages of analog electronics: (1) susceptibility to replication errors due to nonlinearities in the amplification process and (2) susceptibility to signal degradation due to the addition, during the amplification process, of noise originating from the analog devices composing the amplifier. These two disadvantages compete with the primary advantage of analog electronics, the ease of implementing any desired electronic signal manipulation. See also Amplifier; Distortion (electronic circuits); Electrical noise.

Digital electronics

The advent of the transistor in the 1940s made it possible to design simple, inexpensive digital electronic circuits and initiated the explosive growth of digital electronics. Digital signals are represented by a finite set of states rather than a continuum, as is the case for the analog signal. Typically, a digital signal takes on the value 0 or 1; such a signal is called a binary signal. Because digital signals have only a finite set of states, they are amenable to error-correction techniques; this feature gives digital electronics its principal advantage over analog electronics. See also Electron tube; Transistor.

In common two-level digital electronics, signals are manipulated mathematically. These mathematical operations are known as boolean algebra. The operations permissible in boolean algebra are NOT, AND, OR, and XOR, plus various combinations of these elemental operations. See also Boolean algebra.

Electronic circuits are composed of various electronic devices, such as transistors, resistors, and capacitors. In circuits built from discrete components, the components are typically soldered together on a fiberglass board known as a printed circuit board. On one or more surfaces of the printed circuit board are layers of conductive material which has been patterned to form the interconnections between the different components in the circuit. In some cases, the circuits necessary for a particular application are far too complex to build from individual discrete components, and integrated-circuit technology must be employed. Integrated circuits are fabricated entirely from a single piece of semiconductor substrate. It is possible in some cases to put several million electronic devices inside the same integrated circuit. Many integrated circuits can be fabricated on a single wafer of silicon at one time, and at the end of the fabrication process the wafer is sawed into individual integrated circuits. These small pieces, or chips as they are popularly known, are then packaged appropriately for their intended application. See also Capacitor; Integrated circuits; Printed circuit; Resistor.

The microprocessor is the most important integrated circuit to arise from the field of electronics. This circuit consists of a set of subcircuits that can perform the tasks necessary for computation and are the heart of modern computers. Microprocessors that understand large numbers of instructions are called complete instruction set computers (CISCs), and microprocessors that have only a very limited instruction set are called reduced instruction set computers (RISCs). See also Digital computer; Microprocessor.

Other circuit designs have been standardized and reduced to integrated-circuit form as well. An example of this process is seen in the telephone modem. Modulation techniques have been standardized to permit the largest possible data-transfer rates in a given amount of bandwidth, and standardized modem chips are available for use in circuit design. See also Modem.

The memory chip is another important integrated electronic circuit. This circuit consists of a large array of memory cells composed of a transistor and some other circuitry. As the storage capacity of the memory chip has increased, significant miniaturization has taken place. See also Circuit (electronics); Semiconductor memories.

A later development of the work of Albert Abrams (1863-1924) that employs therapeutic apparatus to produce shortwave low-power electromagnetic and alternating magnetic currents to correct disease conditions. Abrams believed that diseases produced peculiar radiations, and that these radiations in turn produce a reflex in living tissue that can be detected by apparatuses and normalized by the appropriate electro-magnetic energy produced by other apparatuses.

In 1922 the College of Electronic Medicine was founded in San Francisco. It was superseded in 1947 by the Electronic Medical Foundation. The magazine Physio-Clinical Medicine, started in 1916, later became the Electronic Medical Digest, reviewing a wide range of developments relating to electromagnetic theories and research in cell radiation and disease therapies.

Sources:

Abrams, Albert. Human Energy. San Francisco: The Author, 1914.

Barr, James. Abrams' Methods of Diagnosis and Treatment. London, 1925.

For personal-use electronic devices, see consumer electronics.

Surface mount electronic components

Electronics is that branch of science and technology which makes use of the controlled motion of electrons through different media and vacuum. The ability to control electron flow is usually applied to information handling or device control. Electronics is distinct from electrical science and technology, which deals with the generation, distribution, control and application of electrical power. This distinction started around 1906 with the invention by Lee De Forest of the triode, which made electrical amplification possible with a non-mechanical device. Until 1950 this field was called "radio technology" because its principal application was the design and theory of radio transmitters, receivers and vacuum tubes.

Most electronic devices today use semiconductor components to perform electron control. The study of semiconductor devices and related technology is considered a branch of physics, whereas the design and construction of electronic circuits to solve practical problems come under electronics engineering. This article focuses on engineering aspects of electronics.

Contents 1 Electronic devices and components 2 Types of circuits 2.1 Analog circuits 2.2 Digital circuits 3 Heat dissipation and thermal management 4 Noise 5 Electronics theory 6 Computer aided design (CAD) 7 Construction methods 8 See also 9 References 10 Further reading 11 External links

Electronic devices and components

Main article: Electronic component

An electronic component is any physical entity in an electronic system used to affect the electrons or their associated fields in a desired manner consistent with the intended function of the electronic system. Components are generally intended to be connected together, usually by being soldered to a printed circuit board (PCB), to create an electronic circuit with a particular function (for example an amplifier, radio receiver, or oscillator). Components may be packaged singly or in more complex groups as integrated circuits. Some common electronic components are capacitors, resistors, diodes, transistors, etc. Components are often categorized as active (e.g. transistors and thyristors) or passive (e.g. resistors and capacitors).

Types of circuits

Circuits and components can be divided into two groups: analog and digital. A particular device may consist of circuitry that has one or the other or a mix of the two types

Analog circuits

Main article: Analog circuits

Hitachi J100 adjustable frequency drive chassis.

Most analog electronic appliances, such as radio receivers, are constructed from combinations of a few types of basic circuits. Analog circuits use a continuous range of voltage as opposed to discrete levels as in digital circuits.

The number of different analog circuits so far devised is huge, especially because a 'circuit' 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. Good examples of analog circuits include vacuum tube and transistor amplifiers, operational amplifiers and oscillators.

One rarely finds modern circuits that are entirely analog. These days analog circuitry may use digital or even microprocessor techniques to improve performance. This type of circuit is usually called "mixed signal" rather than analog or digital.

Sometimes it may be difficult to differentiate between analog and digital circuits as they have elements of both linear and non-linear operation. An example is the comparator which takes in a continuous range of voltage but only outputs one of two levels as in a digital circuit. Similarly, an overdriven transistor amplifier can take on the characteristics of a controlled switch having essentially two levels of output.

Digital circuits

Main article: Digital circuits

Digital circuits are electric 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. To most engineers, the terms "digital circuit", "digital system" and "logic" are interchangeable in the context of digital circuits. Most digital circuits use two voltage levels labeled "Low"(0) and "High"(1). Often "Low" will be near zero volts and "High" will be at a higher level depending on the supply voltage in use. Ternary (with three states) logic has been studied, and some prototype computers made.

Computers, electronic clocks, and programmable logic controllers (used to control industrial processes) are constructed of digital circuits. Digital Signal Processors are another example.

Building-blocks:

• Logic gates
• Adders
• Binary Multipliers
• Flip-Flops
• Counters
• Registers
• Multiplexers
• Schmitt triggers

Highly integrated devices:

• Microprocessors
• Microcontrollers
• Application-specific integrated circuit (ASIC)
• Digital signal processor (DSP)
• Field-programmable gate array (FPGA)

Heat dissipation and thermal management

Main article: Thermal management of electronic devices and systems

Heat generated by electronic circuitry must be dissipated to prevent immediate failure and improve long term reliability. Techniques for heat dissipation can include heat sinks and fans for air cooling, and other forms of computer cooling such as water cooling. These techniques use convection, conduction, & radiation of heat energy.

Noise

Main article: Electronic noise

Noise is associated with all electronic circuits. Noise is defined^[1] as unwanted disturbances superposed on a useful signal that tend to obscure its information content. Noise is not the same as signal distortion caused by a circuit. Noise may be electromagnetically or thermally generated, 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 limitations in physical properties.

Electronics theory

Main article: Mathematical methods in electronics

Mathematical methods are integral to the study of electronics. To become proficient in electronics it is also necessary to become proficient in 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 certain node or the current through a certain branch of a network. A common analytical tool for this is the SPICE circuit simulator.

Also important to electronics is the study and understanding of electromagnetic field theory.

Computer aided design (CAD)

Main article: Electronic design automation

Today's electronics engineers have the ability to design circuits using premanufactured building blocks such as power supplies, semiconductors (such as transistors), and integrated circuits. Electronic design automation software programs include schematic capture programs and printed circuit board design programs. Popular names in the EDA software world are NI Multisim, Cadence (ORCAD), Eagle PCB and Schematic, Mentor (PADS PCB and LOGIC Schematic), Altium (Protel), LabCentre Electronics (Proteus) and many others.

Construction methods

Main article: Electronic packaging

Many different methods of connecting components have been used over the years. For instance, early electronics often used point to point wiring with components attached to wooden breadboards to construct circuits. Cordwood construction and wire wraps were other methods used. Most modern day electronics now use printed circuit boards made of materials such as FR4, or the cheaper (and less hard-wearing) Synthetic Resin Bonded Paper (SRBP, also known as Paxoline/Paxolin (trade marks) and FR2) - characterised by its light yellow-to-brown colour. Health and environmental concerns associated with electronics assembly have gained increased attention in recent years, especially for products destined to the European Union, with its Restriction of Hazardous Substances Directive (RoHS) and Waste Electrical and Electronic Equipment Directive (WEEE), which went into force in July 2006.

See also

Electronics portal

Wikipedia:Books has a book on: An introduction to electronics

Wikibooks has more on the topic of Electronics

• Index of electronics articles
• Audio engineering
• Broadcast engineering
• Computer engineering
• Electronic engineering
• Power electronics
• Marine electronics

References

1. ^ IEEE Dictionary of Electrical and Electronics Terms ISBN 978-0-471-42806-0

Further reading

• The Art of Electronics ISBN 978-0-521-37095-0

External links

• Electrical and electronics web portal
• Electronics tutorials, projects and software
• Navy 1998 Navy Electricity and Electronics Training Series (NEETS)
• DOE 1998 Electrical Science, Fundamentals Handbook, 4 vols.
  • Vol. 1, Basic Electrical Theory, Basic DC Theory
  • Vol. 2, DC Circuits, Batteries, Generators, Motors
  • Vol. 3, Basic AC Theory, Basic AC Reactive Components, Basic AC Power, Basic AC Generators
  • Vol. 4, AC Motors, Transformers, Test Instruments & Measuring Devices, Electrical Distribution Systems
• Electronics at the Open Directory Project
• Lessons in Electric Circuits - A free series of textbooks on the subjects of electricity and electronics.

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Dansk (Danish)
n. - elektronik, elektroniske kredsløb

Nederlands (Dutch)
elektronica

Français (French)
n. - électronique

Deutsch (German)
n. - Elektronik, %

Ελληνική (Greek)
n. - ηλεκτρονική (φυσική ή επιστήμη)

Italiano (Italian)
elettronica

Português (Portuguese)
n. - eletrônica (f)

Русский (Russian)
электроника

Español (Spanish)
n. - electrónica

Svenska (Swedish)
n. - elektronik

中文（简体）(Chinese (Simplified))
电子学

中文（繁體）(Chinese (Traditional))
n. pl. - 電子學
n. - 電子學

한국어 (Korean)
n. pl. - 전자 공학
n. - 전자 장치, 전자 장치의 일부

日本語 (Japanese)
n. - 電子工学, エレクトロニクス

العربيه (Arabic)
‏(الاسم) الالكترونيات‏

עברית (Hebrew)
n. pl. - ‮אלקטרוניקה, ענף הפיסיקה והטכנולוגיה העוסק בהתנהגות אלקטרונים ובתנועתם בתוך חומרים שונים‬
n. - ‮אלקטרוניקה‬

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