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Electronics is the study and use of electrical devices that operate by controlling the flow of electrons or other electrically charged particles in devices such as thermionic valves and semiconductors. The pure study of such devices is considered as a branch of physics, while the design and construction of electronic circuits to solve practical problems is part of the fields of electrical, electronic and computer engineering.

The main uses of electronic circuits are the controlling, processing and distribution of information, and the conversion and distribution of electric power. Both of these uses involve the creation or detection of electromagnetic fields and electric currents. More broadly, most electronics systems fall into the category of either control systems or communication systems.

While electricity had been used for some time to transmit data over telegraphs and telephones, the development of electronics truly began in earnest with the advent of radio. Today, electronic devices perform a much wider variety of tasks.

One way of looking at an electronic system is to divide it into the following parts:

  1. Inputs - Electrical or mechanical sensors (or transducers), which take signals (in the form of temperature, pressure, etc.) from the physical world and convert them into current/voltage signals.
  2. Signal processing circuits - These consist of electronic components connected together to manipulate, interpret and transform the signals.
  3. Outputs - Actuators or other devices (also transducers) that transform current/voltage signals back into useful physical form.

Take as an example a television. Its input is a broadcast signal received by an antenna or fed in through a cable. Signal processing circuits inside the television extract the brightness, colour and sound information from this signal. The output devices are a cathode ray tube that converts electronic signals into a visible image on a screen and magnet driven audio speakers.

AC electronics frequencies are ultimately limited by a heat dissipation barrier at around 50 gigahertz and a plasma resonance barrier at approximately 1 terahertz. Instead of signals manifest in electrical currents, signals in polaritonics are manifest as admixtures of lattice vibrations and electromagnetic waves, and operate in the range of frequencies from 100 gigahertz to approximately 10 terahertz. Photonics, in which signals are manifest purely as electromagnetic waves propagating in non-dispersive media, operates at frequencies on the order of hundreds of terahertz, but is limited in functionality as compared to polaritonics or electronics. Polaritonics bridges the gap between electronics and photonics.


Electronic test equipment

Interconnecting electronic components

Passive components

Active components (solid-state)

Active components (thermionic)

Display devices

Electromechanical sensors and actuators

Thermoelectric devices

Photoelectric devices


Analog circuits

Most analog electronic appliances, such as radio receivers, are constructed from arrays of a few types of circuits.

Digital circuits

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


Complex devices:

Mixed-signal circuits

Mixed-signal circuits, also known as hybrid circuits, are becoming increasingly common. Mixed circuits contain both analog and digital components. analog to digital converters and digital to analog converters are the primary examples. Other examples are transmission gates and buffers.

Heat dissipation

Heat generated by electronic circuitry must be dissipated to improve reliability. Techniques for heat dissipation can include heatsinks and fans for air cooling, and other forms of computer cooling such as liquid cooling for computers .


Associated with all electronic circuits is noise. Types of noise include

Electronics theory

See also

External links

Tutorials and projects

Some other good sites

Last updated: 06-02-2005 14:05:37
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