A rotary switch is a mechanical electrical switch that selects one or more circuits by turning a shaft or knob to discrete positions. Unlike a simple toggle, a rotary switch provides multiple fixed settings, frequently held by detents so the operator can feel each position. A typical assembly mounts on a panel and connects via solder lugs, spade terminals or board-mounted pins.

Construction and characteristics

Internally, a rotary switch uses a rotor that brings a movable contact into contact with one or more stationary contacts arranged in a circle. Switches are described by poles and throws (for example, single-pole, multi-throw), and may be built as stacked wafers to provide multiple independent circuits in the same shaft. Contact materials (silver, gold plating) and the mechanical design determine current and voltage ratings, life expectancy and suitability for signal or power applications.

Types and operation

Common variants include single-pole multi-throw (SPnT), multi-pole multi-throw (MPnT), cam or wafer types, and continuous rotary selectors. Some are "break-before-make" to avoid shorting adjacent circuits; others are "make-before-break" where overlap is desirable. The operator changes state by rotating the shaft; keyed shafts, knobs and indexing mechanisms control position and travel. For general information about electrical switches see switch basics, and for details on mechanical actuation see rotation mechanisms.

Uses and examples

  • Range selection on measurement instruments, such as multimeters.
  • Input or source selection on audio and video equipment.
  • Channel or function selection on industrial control panels and test gear.
  • Routing signals in laboratories, communication systems and legacy telephone or radio equipment.

Rotary switches remain useful where a clear, tactile choice among multiple fixed states is required and where simple, reliable electrical isolation or routing is preferred over digital controls.

Selection, maintenance and distinctions

When choosing a rotary switch consider pole/throw configuration, current and voltage rating, contact material, shaft style and mounting. Maintenance mainly involves keeping contacts clean and replacing worn switches after many cycles; lubrication is rarely used on contact surfaces. A rotary switch is distinct from a rotary encoder: the encoder produces electrical pulses or digital output and often has no fixed contact positions, while the rotary switch provides discrete, hard-wired circuit connections.