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Figure 3-7.—Rotary switch in automobile ignition system.
The rotor in the distributor rotates continually (when in use) in one direction and makes a complete
circle. This is not true for all rotary switches. The ignition switch in an automobile is also a rotary switch.
It usually has four positions (accessory, off, on, start). Unlike the rotor, it does not rotate continually
when in use, can be turned in either direction, and does not move through a complete circle.
Some rotary switches are made with several layers or levels. The arrangement makes possible the
control of several circuits with a single switch. Figure 3-8 is an illustration of a rotary switch with two
layers. Each layer has a selector and 20 contacts. As this switch is rotated, both layers select a single
circuit (contact) of the 20.
Figure 3-8.—Two-layer rotary switch.
The channel selector on some television sets is a multilayer rotary switch. It is also called a WAFER
SWITCH. In a wafer switch, each layer is known as a wafer.
The schematic of the wafer is always drawn to represent the wafer as it would look if viewed from
opposite the operating handle or mechanism. If the wafer has contacts on both sides, two drawings are
used to show the two sides of the wafer. The two drawings are labeled "front" and "rear." The drawing
labeled "front" represents the side of the wafer closest to the operating mechanism.
