Unsourced material may be challenged and removed. Please help improve this article by adding citations to reliable sources. For example, if only four positions are required on a twelve position switch, the washer can be positioned so that only four switching positions can be selected when in use. A special toothed washer that sits below the holding nut can be positioned so that the tooth is inserted into one of a number of slots in a way that limits the number of positions available for selection. Some rotary switches are user configurable in relation to the number of positions.
The cams are notched or cut where the contact should close to complete an electrical circuit. Nylon cams are then mounted behind this mechanism and spring-loaded electrical contacts slide around these cams. Modern rotary switches utilise a "star wheel" mechanism to provide the switching positions, such as at every 30, 45, 60, or 90 degrees. Rotary switches were used as channel selectors on television receivers until the early 1970s, as range selectors on electrical metering equipment, as band selectors on multi-band radios, etc. Thus a rotary switch provides greater pole and throw capabilities than simpler switches do. Usually such a switch has a detent mechanism so it "clicks" from one active position to another rather than stalls in an intermediate position. The switch is layered to allow the use of multiple poles, each layer is equivalent to one pole. It has an array of terminals, arranged in a circle around the rotor, each of which serves as a contact for the "spoke" through which any one of a number of different electrical circuits can be connected to the rotor. These are often chosen when more than 2 positions are needed, such as a three-speed fan or a CB radio with multiple frequencies of reception or "channels".Ī rotary switch consists of a spindle or "rotor" that has a contact arm or "spoke" which projects from its surface like a cam. A rotary switch is a switch operated by rotation.
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