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Rotary switch

technology Maturity 11-13 Next article →

A rotary switch is a tool used to control electricity.

rotaryswitch
rotaryswitch

It works by turning in a circle to pick different paths. You might use one for a fan with three speeds. They also work for radios with many channels. This tool is great when you need more than two positions. It lets you choose between many different electrical circuits.

rotaryswitch
rotaryswitch

Inside, the switch has a spinning part called a rotor. A small arm called a spoke sticks out from it. This spoke moves around a circle of metal points called terminals. When the spoke touches a terminal, the circuit connects.

rotaryswitch
rotaryswitch

Most switches have a detent mechanism to help them work. This makes the switch click into a set position. It stops the switch from getting stuck in the middle.

Many switches use layers to do more work. Each layer is called a pole. Using multiple poles lets the switch control many paths at once.

rotaryswitch
rotaryswitch

Some switches only turn a fraction of a circle. They might only turn a third or a half of a circle. This can still let each layer have many poles. This design gives the switch many different ways to work.

Modern switches use a special star wheel mechanism. This part helps the switch move to exact spots. It might move every 30, 45, 60, or 90 degrees.

rotaryswitch
rotaryswitch

Nylon cams sit behind this wheel to guide the parts. Spring-loaded contacts slide around these notched cams. The notches tell the contact when to close a circuit. This makes the switching very precise.

People used these switches in many old machines. They were in television receivers until the early 1970s. They also worked in radios to select different bands.

rotaryswitch
rotaryswitch

You can even change how many spots a switch has. A special toothed washer can limit the positions. You could turn a twelve-position switch into a four-position switch. This makes the tool fit exactly what you need.

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