Digital electronics

Digital electronics represent signals by discrete bands of analog levels, rather than by a continuous range. All levels within a band represent the same signal state. Relatively small changes to the analog signal levels due to manufacturing tolerance, signal attenuation or parasitic noise do not leave the discrete envelope, and as a result are ignored by signal state sensing circuitry.

In most cases the number of these states is two, and they are represented by two voltage bands: one near a reference value (typically termed as "ground" or zero volts) and a value near the supply voltage, corresponding to the "false" ("0") and "true" ("1") values of the boolean domain respectively.

• 

  An industrial digital controller

• 

  Intel 80486DX2 microprocessor

Digital techniques are useful because it is easier to get an electronic device to switch into one of a number of known states than to accurately reproduce a continuous range of values.

Digital electronic circuits are usually made from large assemblies of logic gates, simple electronic representations of Boolean logic functions.^[1]

• 1 Advantages
• 2 Disadvantages
• 3 Analog issues in digital circuits
• 4 Construction
  • 4.1 Structure of digital systems
  • 4.2 Automated design tools
  • 4.3 Design for testability
  • 4.4 Trade-offs
  • 4.5 Logic families
• 5 Non-electronic logic
• 6 Recent developments
• 7 See also
• 8 References
• 9 External links

Electronic engineering

Electronic components

Electronics engineering,^[1] also referred to as electronic engineering,^[2][3] is an engineering discipline where non-linear and active electrical components such as electron tubes, and semiconductor devices, especially transistors, diodes and integrated circuits, are utilized to design electronic circuits, devices and systems, typically also including passive electrical components and based on printed circuit boards. The term denotes a broad engineering field that covers important subfields such as analog electronics, digital electronics, consumer electronics, embedded systems and power electronics. Electronics engineering deals with implementation of applications, principles and algorithms developed within many related fields, for example solid-state physics, radio engineering, telecommunications, control systems, signal processing, systems engineering, computer engineering, instrumentation engineering, electric power control, robotics, and many others.^{[4][verification needed]}

The Institute of Electrical and Electronics Engineers (IEEE) is one of the most important and influential organizations for electronics engineers.

• 1 Relationship to electrical engineering
• 2 History of electronic engineering
  • 2.1 Early electronics
  • 2.2 Tubes or valves
    • 2.2.1 The vacuum tube detector
  • 2.3 Television
  • 2.4 Radar and radio location
  • 2.5 Computers
  • 2.6 Microprocessors
• 3 Electronics
• 4 Typical electronic engineering undergraduate syllabus
  • 4.1 Electromagnetics
  • 4.2 Network analysis
  • 4.3 Electronic devices and circuits
  • 4.4 Signals and systems
  • 4.5 Control systems
  • 4.6 Communications
• 5 Education and training
• 6 Professional bodies
• 7 Subfields
  • 7.1 Overview of electronic engineering
  • 7.2 Project engineering
• 8 See also
• 9 References
• 10 External links

Electronic circuit

The die from an Intel 8742, an 8-bit microcontroller that includes a CPU, 128 bytes of RAM, 2048 bytes of EPROM, and I/O in the same chip.

A circuit built on a printed circuit board (PCB).

An electronic circuit is composed of individual electronic components, such as resistors, transistors, capacitors, inductors and diodes, connected by conductive wires or traces through which electric current can flow. The combination of components and wires allows various simple and complex operations to be performed: signals can be amplified, computations can be performed, and data can be moved from one place to another.^[1] Circuits can be constructed of discrete components connected by individual pieces of wire, but today it is much more common to create interconnections by photolithographic techniques on a laminated substrate (a printed circuit board or PCB) and solder the components to these interconnections to create a finished circuit. In an Integrated Circuit or IC, the components and interconnections are formed on the same substrate, typically a semiconductor such as silicon or (less commonly) gallium arsenide.^[2]

Breadboards, perfboards or stripboards are common for testing new designs. They allow the designer to make quick changes to the circuit during development.

An electronic circuit can usually be categorized as an analog circuit, a digital circuit or a mixed-signal circuit (a combination of analog circuits and digital circuits).

• 1 Analog circuits
• 2 Digital circuits
• 3 Mixed-signal circuits
• 4 References
• 5 External links

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Engineering

The Watt steam engine, a major driver in the Industrial Revolution, underscores the importance of engineering in modern history. This model is on display at the main building of the ETSIIM in Madrid, Spain

Engineering is the discipline, art, skill and profession of acquiring and applying scientific, mathematical, economic, social, and practical knowledge to design and build structures, machines, devices, systems, materials and processes that safely realize improvements to the lives of people.

The American Engineers' Council for Professional Development (ECPD, the predecessor of ABET)^[1] has defined "engineering" as:

[T]he creative application of scientific principles to design or develop structures, machines, apparatus, or manufacturing processes, or works utilizing them singly or in combination; or to construct or operate the same with full cognizance of their design; or to forecast their behavior under specific operating conditions; all as respects an intended function, economics of operation and safety to life and property.^[2][3][4]

One who practices engineering is called an engineer, and those licensed to do so may have more formal designations such as Professional Engineer, Chartered Engineer, Incorporated Engineer, Ingenieur or European Engineer. The broad discipline of engineering encompasses a range of more specialized subdisciplines, each with a more specific emphasis on certain fields of application and particular areas of technology.

• 1 History
  • 1.1 Ancient era
  • 1.2 Renaissance era
  • 1.3 Modern era
• 2 Main branches of engineering
• 3 Methodology
  • 3.1 Problem solving
  • 3.2 Computer use
• 4 Social context
• 5 Relationships with other disciplines
  • 5.1 Science
  • 5.2 Medicine and biology
  • 5.3 Art
  • 5.4 Other fields
• 6 See also
• 7 References
• 8 Further reading
• 9 External links

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Triode

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Structure of a vacuum tube triode

A triode is an electronic amplification device having three active electrodes. The term most commonly applies to a vacuum tube (or valve in British English) with three elements: the filament or cathode, the grid, and the plate or anode. The triode vacuum tube is the first electronic amplification device. The word is derived from the Greek τρίοδος, tríodos, from tri- (three) and hodós (road, way), originally meaning the place where three roads meet.

• 1 Invention
• 2 Operation
• 3 Applications
• 4 Characteristics
• 5 See also
• 6 References
• 7 External links

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Transmitter

Antenna tower of Crystal Palace transmitter, London

In electronics and telecommunications a transmitter or radio transmitter is an electronic device which, with the aid of an antenna, produces radio waves. The transmitter itself generates a radio frequency alternating current, which is applied to the antenna. When excited by this alternating current, the antenna radiates radio waves. In addition to their use in broadcasting, transmitters are necessary component parts of many electronic devices that communicate by radio, such as cell phones, Wifi and Bluetooth enabled devices, garage door openers, two-way radios in aircraft, ships, and spacecraft, radar sets, and navigational beacons. The term transmitter is usually limited to equipment that generates radio waves for communication purposes; or radiolocation, such as radar and navigational transmitters. Generators of radio waves for heating or industrial purposes, such as microwave ovens or diathermy equipment, are not usually called transmitters even though they often have similar circuits.

The term is popularly used more specifically to refer to transmitting equipment used for broadcasting, as in radio transmitter or television transmitter. This usage usually includes both the transmitter proper as described above, and the antenna, and often the building it is housed in.

An unrelated use of the term is in industrial process control, where a "transmitter" is a device which converts measurements from a sensor into a signal, and sends it, usually via wires, to be received by some display or control device located a distance away.

• 1 Description
• 2 Legal restrictions
• 3 How it works
• 4 History
• 5 Broadcast transmitters
  • 5.1 Frequency Control
  • 5.2 Power output
  • 5.3 Power supply
  • 5.4 Cooling of final stages
  • 5.5 Protection equipment
  • 5.6 Building
  • 5.7 Legal and regulatory aspects
  • 5.8 Planning
  • 5.9 Main and relay (repeater) transmitters
• 6 Transmitters in culture
• 7 Records
• 8 References
• 9 See also
• 10 External links

Receiver (radio)

A radio receiver is an electronic circuit that receives its input from an antenna, uses electronic filters to separate a wanted radio signal from all other signals picked up by this antenna, amplifies it to a level suitable for further processing, and finally converts through demodulation and decoding the signal into a form usable for the consumer, such as sound, pictures, digital data, measurement values, navigational positions, etc.^[1]

Early broadcast radio receiver--wireless Truetone model from about 1940

In consumer electronics, the terms radio and radio receiver are often used specifically for receivers designed for the sound signals transmitted by radio broadcasting services – historically the first mass-market radio application.

• 1 Types of radio receivers
• 2 Consumer audio receivers
  • 2.1 Hi-Fi / Home theater
  • 2.2 Portable radios
• 3 History of radio receivers
  • 3.1 Early development
  • 3.2 Valves (Tubes)
  • 3.3 Autodyne and superheterodyne
  • 3.4 War and postwar developments
  • 3.5 Semiconductors
  • 3.6 Digital technologies
  • 3.7 DSP technology
  • 3.8 PC controlled radio receivers
  • 3.9 Radio control software
  • 3.10 Software-defined radios
• 4 See also
• 5 Notes
• 6 References

Wire

It has been suggested that this article be split into articles titled Wire (electrical conductor) and Wire (metal rope), accessible from a disambiguation page. (Discuss)

Wires overhead

A wire is a single, usually cylindrical, flexible strand or rod of metal. Wires are used to bear mechanical loads and to carry electricity and telecommunications signals. Wire is commonly formed by drawing the metal through a hole in a die or draw plate. Standard sizes are determined by various wire gauges. The term wire is also used more loosely to refer to a bundle of such strands, as in 'multistranded wire', which is more correctly termed a wire rope in mechanics, or a cable in electricity.

Although usually circular in cross-section, wire is also made in square or flattened rectangular cross-section, either for decorative purposes, or for technical purposes such as high-efficiency voice coils in loudspeakers. Edge-wound^[1] coil springs, such as the "Slinky" toy, are made of special flattened wire.

• 1 History
• 2 Uses
• 3 Production
• 4 Finishing, jacketing, and insulating
• 5 Solid versus stranded
  • 5.1 Number of strands
• 6 Varieties
• 7 See also
• 8 References
• 9 External links

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Transformer

Pole-mounted power distribution transformer with center-tapped secondary winding (note use of grounded conductor, right, as one leg of the primary feeder). It transforms the high voltage of the overhead distribution wires to the lower voltage used in house wiring.

A transformer is a static device that transfers electrical energy from one circuit to another through inductively coupled conductors—the transformer's coils. A varying current in the first or primary winding creates a varying magnetic flux in the transformer's core and thus a varying magnetic field through the secondary winding. This varying magnetic field induces a varying electromotive force (EMF) or "voltage" in the secondary winding. This effect is called mutual induction.

If a load is connected to the secondary, an electric current will flow in the secondary winding and electrical energy will be transferred from the primary circuit through the transformer to the load. In an ideal transformer, the induced voltage in the secondary winding (V_s) is in proportion to the primary voltage (V_p), and is given by the ratio of the number of turns in the secondary (N_s) to the number of turns in the primary (N_p) as follows:

By appropriate selection of the ratio of turns, a transformer thus allows an alternating current (AC) voltage to be "stepped up" by making N_s greater than N_p, or "stepped down" by making N_s less than N_p.

In the vast majority of transformers, the windings are coils wound around a ferromagnetic core, air-core transformers being a notable exception.

Transformers range in size from a thumbnail-sized coupling transformer hidden inside a stage microphone to huge units weighing hundreds of tons used to interconnect portions of power grids. All operate with the same basic principles, although the range of designs is wide. While new technologies have eliminated the need for transformers in some electronic circuits, transformers are still found in nearly all electronic devices designed for household ("mains") voltage. Transformers are essential for high-voltage electric power transmission, which makes long-distance transmission economically practical.

• 1 History
  • 1.1 Discovery
  • 1.2 Induction coils
  • 1.3 Closed-core transformers and the introduction of parallel connection
  • 1.4 Other early transformers
• 2 Basic principles
  • 2.1 Induction law
  • 2.2 Ideal power equation
  • 2.3 Detailed operation
• 3 Practical considerations
  • 3.1 Leakage flux
  • 3.2 Effect of frequency
  • 3.3 Energy losses
  • 3.4 Dot convention
• 4 Equivalent circuit
• 5 Types
  • 5.1 Autotransformer
  • 5.2 Polyphase transformers
  • 5.3 Leakage transformers
  • 5.4 Resonant transformers
  • 5.5 Audio transformers
  • 5.6 Instrument transformers
• 6 Classification
• 7 Construction
  • 7.1 Cores
    • 7.1.1 Laminated steel cores
    • 7.1.2 Solid cores
    • 7.1.3 Toroidal cores
    • 7.1.4 Air cores
  • 7.2 Windings
  • 7.3 Coolant
  • 7.4 Insulation drying
  • 7.5 Terminals
• 8 Applications
• 9 See also
• 10 Notes
• 11 References
• 12 External links

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Resistor

A typical axial-lead resistor

Partially exposed Tesla TR-212 1 kΩ carbon film resistor

Axial-lead resistors on tape. The tape is removed during assembly before the leads are formed and the part is inserted into the board.

Three carbon composition resistors in a 1960s valve (vacuum tube) radio

A resistor is a two-terminal passive electronic component which implements electrical resistance as a circuit element. When a voltage V is applied across the terminals of a resistor, a current I will flow through the resistor in direct proportion to that voltage. This constant of proportionality is called conductance, G. The reciprocal of the conductance is known as the resistance R, since, with a given voltage V, a larger value of R further "resists" the flow of current I as given by Ohm's law:

Resistors are common elements of electrical networks and electronic circuits and are ubiquitous in most electronic equipment. Practical resistors can be made of various compounds and films, as well as resistance wire (wire made of a high-resistivity alloy, such as nickel-chrome). Resistors are also implemented within integrated circuits, particularly analog devices, and can also be integrated into hybrid and printed circuits.

The electrical functionality of a resistor is specified by its resistance: common commercial resistors are manufactured over a range of more than 9 orders of magnitude. When specifying that resistance in an electronic design, the required precision of the resistance may require attention to the manufacturing tolerance of the chosen resistor, according to its specific application. The temperature coefficient of the resistance may also be of concern in some precision applications. Practical resistors are also specified as having a maximum power rating which must exceed the anticipated power dissipation of that resistor in a particular circuit: this is mainly of concern in power electronics applications. Resistors with higher power ratings are physically larger and may require heat sinking. In a high voltage circuit, attention must sometimes be paid to the rated maximum working voltage of the resistor.

The series inductance of a practical resistor causes its behavior to depart from ohms law; this specification can be important in some high-frequency applications for smaller values of resistance. In a low-noise amplifier or pre-amp the noise characteristics of a resistor may be an issue. The unwanted inductance, excess noise, and temperature coefficient are mainly dependent on the technology used in manufacturing the resistor. They are not normally specified individually for a particular family of resistors manufactured using a particular technology.^[1] A family of discrete resistors is also characterized according to its form factor, that is, the size of the device and position of its leads (or terminals) which is relevant in the practical manufacturing of circuits using them.

• 1 Units
• 2 Theory of operation
  • 2.1 Ohm's law
  • 2.2 Series and parallel resistors
  • 2.3 Power dissipation
• 3 Construction
  • 3.1 Lead arrangements
  • 3.2 Carbon composition
  • 3.3 Carbon film
  • 3.4 Thick and thin film
  • 3.5 Metal film
  • 3.6 Metal Oxide film
  • 3.7 Wirewound
  • 3.8 Foil resistor
  • 3.9 Ammeter shunts
  • 3.10 Grid resistor
  • 3.11 Special varieties
• 4 Variable resistors
  • 4.1 Adjustable resistors
  • 4.2 Potentiometers
  • 4.3 Resistance decade boxes
  • 4.4 Special devices
• 5 Measurement
• 6 Standards
  • 6.1 Production resistors
  • 6.2 Resistance standards
• 7 Resistor marking
  • 7.1 Four-band resistors
  • 7.2 Preferred values
  • 7.3 5-band axial resistors
  • 7.4 SMD resistors
  • 7.5 Industrial type designation
• 8 Electrical and thermal noise
• 9 Failure modes
• 10 See also
• 11 References
• 12 External links