c. Inductors.
While not used as extensively as resistors and
capacitors, inductors (or coils) are still a common basic component
of many electrical and electronic circuits.
An inductor has the
property of opposing a change in the existing current. The standard
symbol for an inductor is shown in figure 1-9.
Inductors are
generally labeled with the letter "L" and are rated in henrys, the
basic unit of inductance. In most practical applications, the actual
rating will be given in millihenrys or microhenrys.
Figure 1-9.
Air Core Inductor.
Inductors, like the other basic components, come in a variety of
configurations.
They may be variable, tapped, aircore, iron core,
etc. Figure 1-10 illustrates the symbols used for some variations of
inductors.
Figure 1-10.
Special Purpose Inductors.
4.
Every electrical circuit must have a source of
electrical power. Some electrical and/or electronic devices have an
internal power source, but most rely on some external source to
supply the power necessary to operate them.
When the power source is external to the particular schematic diagram
being examined, generally only the connectors bringing in the power
are identified and labeled with the appropriate originating source.
However, when the source of the power for a given circuit is internal
to the schematic, it must be identified and represented by the
appropriate schematic symbol.
Most electrical and electronic equipment is operated by "plugging" it
into an external power source, or by some installed power source
(usually a battery).
As previously stated, external power sources
are usually identified on a schematic diagram by their point of entry
into the circuit.
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OD1725
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