18/11/2014
Various electronic components
An electronic component is any basic discrete
device or physical entity in an electronic
system used to affect electrons or their
associated fields. Electronic components are
mostly industrial products, available in a
singular form and are not to be confused with
electrical elements , which are conceptual
abstractions representing idealized electronic
components.
Electronic components have two or more
electrical terminals (or leads ) aside from
antennas which may only have one terminal.
These leads connect, usually soldered to a
printed circuit board, to create an electronic
circuit (a discrete circuit) with a particular
function (for example an amplifier , radio
receiver , or oscillator). Basic electronic
components may be packaged discretely, as
arrays or networks of like components, or
integrated inside of packages such as
semiconductor integrated circuits, hybrid
integrated circuits , or thick film devices. The
following list of electronic components
focuses on the discrete version of these
components, treating such packages as
components in their own right.
Classification
A component may be classified as passive,
active , or electromechanic. The strict physics
definition treats passive components as ones
that cannot supply energy themselves,
whereas a battery would be seen as an active
component since it truly acts as a source of
energy.
However, electronic engineers who perform
circuit analysis use a more restrictive
definition of passivity . When only concerned
with the energy of signals , it is convenient to
ignore the so-called DC circuit and pretend
that the power supplying components such as
transistors or integrated circuits is absent (as
if each such component had its own battery
built in), though it may in reality be supplied
by the DC circuit. Then, the analysis only
concerns the AC circuit, an abstraction that
ignores DC voltages and currents (and the
power associated with them) present in the
real-life circuit. This fiction, for instance, lets
us view an oscillator as "producing energy"
even though in reality the oscillator consumes
even more energy from a DC power supply,
which we have chosen to ignore. Under that
restriction, we define the terms as used in
circuit analysis as:
Active components rely on a source of
energy (usually from the DC circuit, which we
have chosen to ignore) and usually can inject
power into a circuit, though this is not part of
the definition. [1] Active components include
amplifying components such as transistors,
triode vacuum tubes (valves), and tunnel
diodes.
Passive components can't introduce net
energy into the circuit. They also can't rely on
a source of power, except for what is
available from the (AC) circuit they are
connected to. As a consequence they can't
amplify (increase the power of a signal),
although they may increase a voltage or
current (such as is done by a transformer or
resonant circuit). Passive components include
two-terminal components such as resistors,
capacitors, inductors, and transformers.
Electromechanical components can carry
out electrical operations by using moving
parts or by using electrical connections
Most passive components with more than two
terminals can be described in terms of two-
port parameters that satisfy the principle of
reciprocity—though there are rare exceptions.
[2] In contrast, active components (with more
than two terminals) generally lack that
property.
