Chapter 8 Electrical Engineering 151
There are a wide variety of capacitors, but
the ceramic disc and electrolytic are the most
common. Both work the same way, but electro-
lytic capacitors can hold much more charge. See
Figure 8-20.
A capacitor is made up of two conductive
plates separated by a thin layer of insulation
called a dielectric. When a capacitor is connected
to a power source, current will fl ow for a short
period of time until the negative plate has gained
enough electrons to reach saturation. This nega-
tive charge repels electrons from the opposite
plate causing it to take on a positive charge. See
Figure 8-21.
Capacitors can maintain a charge long after
the power source is removed. When working with
capacitors, it is important to treat them as if they
are charged and capable of delivering a shock.
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Enlarged view of
NPN transistor construction
Collector
P-type
base
c
c
b
b
e
e
Emitter
Substrate
N-type
N-type
Enlarged view of
PNP transistor construction
Collector
N-type base
c
b
e
Emitter
Substrate
P-type
P-type
c
b
e
A
B
Figure 8-19.
Bipolar transistor
construction and schematic
symbols are shown. The
three junction points are the
emitter (e), the base (b),
and the collector (c).
A—An NPN transistor.
B—A PNP transistor.
Shown are types of ceramic disc and electrolytic
capacitors.
Figure 8-20.
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