Rotary Switches

A rotary switch is used on devices which have two or more different modes of operation or "states" of operation. For example such types of switch is used in in three-speed fan having multiple frequencies or a CB radio with multiple channels of receptions. .

This electromagnetic rotary switch has a rotating shaft connected to one terminal and is capable of making or breaking a connection to one or more other terminals.

The switch consists of a shaft or "rotor", having a contact arm or "spoke" which projects from its surface like a cam. The switch has an array of terminals that are arranged in a circle around the rotor. Each of these serve as a contact for the "spoke" through which any one of a number of different electrical circuits can be connected to the rotor.

The switches move in a circle and can stop in several positionsand are available in two styles: single-deck and multi-deck. Both the types of switches can be actuated with the help of a bare or knobbed shaft, a flush actuator, or a key.

Materials of Construction
These rotary switches are mostly made of plastic or metallic materials. Certain parameters should be kept in mind while selecting rotary switches. These are:

• Stop style: Switches are available in adjustable or continuous stop.
  
  
• Contact style: Switches are available in shorting and non-shorting contact styles.
  
  
• Terminal type: These include PCB pins, solder terminals, screw terminals and wire leads.
  
  

Rotary Switches Approvals: Switches get approval and certifications from reputed associations and industrial bodies including Canadian Standards Association (CSA), and Underwriters Laboratories (UL).


Applications
Rotary switches are used in diverse areas and products including:

• Channel selectors on older television sets
• Range selectors on electrical metering equipment
• Band selectors on multi-band radios