Switches are the foundation on which nearly all electrical devices are built. They are designed to connect or disconnect a circuit. When connected, the circuit is closed. When disconnected, the circuit is open. To achieve this goal, however, switches require contacts. What are switch contacts exactly, and how do they work?
What Is a Switch Contact?
A switch contact is a conductive component or surface that’s used to control a circuit. Circuits, of course, generally consist of nothing more than a conductive path. The conductive path allows electricity to flow from one end to the opposite end when the circuit is closed. If the circuit is open, on the other hand, electricity won’t pass through it.
Switches contain contacts to provide a conductive path for electricity. Most switches have two contacts. The contacts are made of a conductive material, such as metal, that create little or no resistance for electricity. When you press a switch’s button, the two contacts will meet, thereby completing the circuit.
Pressing a switch’s button will cause a top contact to push into a bottom contact. Since both the contacts are conductive, electricity can flow through them. This essentially completes the circuit so that the keypad or device can register your command. While all switches have contacts, though, there are many different types of switches.
A push-button switch is a type of switch that requires pressing or pushing each time to change the orientation of its circuit. In other words, you have to repress a push-button switch to open or close the circuit back to its original state.
Some switches revert back to their circuit’s original state naturally when you release your finger from the button. You may be able to close the circuit by pressing a switch’s button, and when you release your finger, the switch will “spring” back to its original position where the circuit is closed. A push-button switch works in a different way. Its circuit will remain open until you repress the button.
There are also capacitive switches. Capacitive switches are unique because they generally don’t contain electrical contacts — at least not the same type of electrical contacts found in traditional switches. Instead, they measure capacitance to determine when the circuit should open or close.
Capacitive switches use a similar technology as capacitive touchscreens. They apply a voltage to the button. When you press the button, its voltage will change. Capacitive switches will register this information, and they’ll use it to open or close the circuit.