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Pushbutton Switches

Pushbutton switches are a type of control switch used to turn on or off electronic circuits or devices. They are also known as momentary contact switches, because they require continuous pressure to remain in the engaged position. These switches typically consist of a set of contacts located within a sealed housing, and pushed against each other with spring tension when the button is pressed. They can be either manually operated or connected to a computer or other control system for automated operation.

1.1 Applications

Pushbutton switches are used to control a wide variety of electronic equipment, such as microwaves, blenders, espresso machines, computers and cell phones. They can also be used to operate door locks, motor vehicle transmission systems, monorail systems and other automated systems. The switch design depends on the application: some designs may be suitable for low current intensity and be triggered by a short contact (for example, a simple pushbutton switch used to switch between two device settings); whilst others are designed to handle high-current intensity and require a longer contact (for example a pushbutton switch used to control an electric motor).

1.2 Principle of Operation

The principle of operation of a pushbutton switch is fairly straightforward. When the button is pressed, the mechanical contacts inside the switch move into contact with each other, creating a conducting path that enables power to be transmitted from one terminal to another. When the button is released, the contacts move apart and the path is broken, thus stopping the power transmission.Pushbutton switches are typically made from a conductive material such as metal, with a plastic housing and a spring-loaded plunger to created the electrical connection. The contacts may be either normally open (NO) or normally closed (NC), meaning they remain open or closed until the switch is activated.In addition, certain switches can be latched, meaning they remain in the activated position after the button has been released.

1.3 Types of Pushbutton Switches

Pushbutton switches come in a variety of forms, including toggle (two contact positions, one normally open and one normally closed), rotary (where the switch is triggered at different positions by rotating the contact) and push-on, push-off (where a single contact is switched on or off with each press of the button).There are also numerous specific designs available, such as illuminated switches (which have an LED embedded in the contact button), vandal resistant switches (which are stronger and more robust against impact), and waterproof/dustproof switches (which are sealed against moisture and dust).Each specific type of switch also varies according to its electrical ratings, with voltage and current ratings clearly indicated on the switching device. Ratings are generally expressed in volts and amperes (V, A) or milliamps (mA).