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Figure 3-17A.—Silicon controlled rectifier.
Figure 3-17B.—Silicon controlled rectifier.
Although it is not the same as either a diode or a transistor, the SCR combines features of both.
Circuits using transistors or rectifier diodes may be greatly improved in some instances through the use of
SCRs.
The basic purpose of the SCR is to function as a switch that can turn on or off small or large amounts
of power. It performs this function with no moving parts that wear out and no points that require
replacing. There can be a tremendous power gain in the SCR; in some units a very small triggering
current is able to switch several hundred amperes without exceeding its rated abilities. The SCR can often
replace much slower and larger mechanical switches. It even has many advantages over its more complex
and larger electron tube equivalent, the thyratron.
