Switches - Common Terms

Switches – what do these terms mean?

A switch is an electromechanical or electronic device used for controlling the continuity between two points in a circuit. It can cut off or allow current to flow in a circuit. A switch needs an actuator which can be manually or electrically operated for keeping a circuit open or closed. There are a wide variety of switches available depending on application and they are an important electronic component of any circuit.

A Normally Open switch closes the circuit when activated while a Normally Closed switch does the opposite.

The Central Office (CO) switch is the central network element in a telecommunication network that establishes temporary connection between 2 subscribers. The CO switch terminates subscriber lines and interoffice trunk lines. It is responsible for providing the basic features of placing a call like dial tone, signaling other equipments about the call, identifying touch tones as well as keeping a record of the call.

A momentary switch is a switch that returns to its normal position when released. A door bell is an example of momentary switch. A push switch can be a momentary switch or latching type. In the case of former, the switch acts only as long as the switch is pressed. In a latching type switch, the button stays down when pressed. The contacts may remain closed or open depending on the type of switch. In order to return to normal state, the button needs to be pressed again. Thus the switch is pushed once to switch on and pushed again to switch off or vice versa. This is known as latching action.