What Is a Rotary Switch?
A rotary switch is a switch that switches contact points by turning.
Rotary switches are used for volume control of audio components, knobs of microwave ovens, etc. Most rotary switches are used to switch multiple contacts, but they are sold with only one contact. Most rotary switches are used to switch multiple contacts, but switches that switch only one contact are also available. Recently, ultra-compact rotary switches have been developed, contributing to the miniaturization of audio equipment and other devices.
Uses of Rotary Switches
Rotary switches are used in a wide range of applications, from familiar home appliances to industrial equipment.
Specific applications are as follows:
- Volume control of audio components
- Setting the output of microwave ovens
- Switching power and strength of electric fans
- Switching the volume of measuring machines and communication equipment
- Switching of control board settings for inverters, air conditioners, etc.
Recently, pendant lights that use a single-contact rotary switch to operate the power supply are also available to create a retro atmosphere. Also, in recent years, they are sometimes used as power switching switches for portable LED lighting as part of DIY projects.
Principle of Rotary Switches
A rotary switch consists of a sliding element, a case/fixed contact, and a terminal.
The sliding element moves simultaneously with the movable contacts and switches the contacts according to the operation. The switched contacts conduct two or more fixed contacts attached to the case. The contact output of the fixed contacts is output to the outside through the terminals.
Types of Rotary Switches
There are two types of rotary switches: non-shorting type and shorting type. Proper selection is necessary because the circuit may break down if an inappropriate type is chosen for the intended use.
1. Shorting Type
The shorting type is a type in which two or more contacts conduct simultaneously when switching contacts. It is characterized by the fact that there is no moment of circuit breakdown. Therefore, a temporary state of electrical connection between contacts occurs.
This type is used when temporary disconnection is unacceptable, such as in the tap-switching circuit of a transformer. The shorting type is also called make-before-break. In English, it means “connected before the contacts are separated.”
2. Non-Shorting Type
The Non-Shorting Type is a type in which adjacent terminals are completely independent of each other, and the circuit is disconnected once when the contacts are switched. In this type, when switching contacts, both contacts are electrically disconnected for a moment.
Therefore, this type is used when temporary disconnection due to switching is not a problem. In general applications, the non-shorting type is used in most cases. The non-shorting type is also called break-before-make. In English, it means “to leave before the contacts are connected.
Other Information on Rotary Switches
1. How to Use a Rotary Switch
Rotary switches are used to switch circuits by rotating the actuator. They are often used to set up digital circuits. They are used when the switching frequency is not high, for example, for setting purposes.
There are various types of rotary switches, such as those with flat actuators or shaft-shaped actuators. Depending on the shape, some products can be operated with a finger, while others require a screwdriver or similar tool.
2. Thumb Rotary Switch
Among rotary switches, there are thumb rotary switches. This is a rotary switch that uses a disk-shaped part with numbers written on the switch display. They are characterized by their ease of visual confirmation and are used for setting channels on old radio equipment.
A typical thumb rotary switch consists of parts such as a case, pushbutton, slide, rotor, printed circuit board, and mounting plate.