ELECTRONIC PRINCIPLES - OD1647 - LESSON 1/TASK 1
l. Fixed Capacitors. A fixed capacitor is constructed in such
a manner that it possesses a fixed value of capacitance which
cannot be adjusted. A fixed capacitor is classified according
to the type of material used as its dielectric, such as paper,
oil, mica, or electrolyte.
(1) Paper Capacitors. A PAPER CAPACITOR is made of flat think
strips of metal foil conductors that are separated by waxed
paper (the dielectric material). Paper capacitors usually range
in value from about 300 picofarads to about 4 microfarads. The
working voltage of a paper capacitor rarely exceeds 600 volts.
Paper capacitors are sealed with wax to prevent the harmful
effects of moisture and to prevent corrosion and leakage.
Many different kinds of outer coverings are used on paper
capacitors, the simplest being a tubular cardboard covering.
Some types of paper capacitors are encased in very hard plastic.
These types are very rugged and can be used over a much wider
temperature range than can the tubular cardboard type. Figure
41, view A, shows the construction of a tubular paper capacitor;
figure 41, view B, shows a completed cardboardencased capacitor.
FIGURE 41. PAPER CAPACITOR.