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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 called electronic engineering.
The main uses of electronic circuits are the controlling, processing and distribution of information, and the conversion and distribution of electrical power. Both of these uses involve the creation or detection of electromagnetic fields and electric currents.
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:
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.
Signal processing circuits - These consist of electronic components connected together to manipulate, interpret and transform the signals.
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.
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Ammeter, e.g. Galvanometer (Measure current)
Ohmmeter, e.g. Wheatstone bridge (Measure resistance)
Voltmeter (Measures voltage)
Multimeter (Measures all of the above)
Logic analyzer (Tests digital circuits)
Oscilloscope (Measures all of the above as they change over time)
Electrometer (Measures charge)
electrical connectors, plugs and sockets etc.
printed circuit boards
integrated circuit
point-to-point construction
wire-wrap
breadboard
resistor
capacitor
inductor
transformer
piezoelectric crystal
magnetic amplifier (toroid)
diode
light emitting diode
photodiode
laser diode
Zener diode
Schottky diode
transient voltage suppression diode
variable capacitance diode
transistor
field effect transistor
bipolar transistor
IGBT transistor
Darlington transistor
photo transistor
other active components
triac
thyristor
unijunction transistor
varistor
Silicon Controlled Rectifier (SCR)
thermionic valve
cathode ray tube
klystron
magnetron
microphone
loudspeaker
strain gauge
switch
thermistor
thermocouple
thermopile
Peltier cooler
light-dependent resistor
photodiode
photovoltaic cell (solar cell)
radio antenna
Most analog electronic appliances, such as radio receivers, are constructed from arrays of a few types of circuits.
Analog computer
Analog multipliers
electronic amplifiers
electronic filters
electronic oscillators
electronic mixers
electronic power supply
impedance matchers
operational amplifiers
Computers, electronic clocks, and programmable logic controllers (used to control industrial processes) are constructed of digital circuits. Digital Signal Processors are another example.
logic gates
flip-flops
counters
registers
multiplexers
microprocessors
microcontrollers
DSP
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.
Associated with all electronic circuits is noise. Types of noise include
Shot noise in resistors.
Thermal noise in resistors.
White noise
Coloured noise
Mathematical Methods of Electronics
Digital Electronics
Analog Electronics
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