Microswitches are tiny switching elements which are characterized by the fact that the distance between the contacts in the open state is less than three millimetres. They are used in a wide range of applications: in consumer electronics as well as in professional and industrial applications. For example, a microswitch can be used to switch an electrical consumer on and off or to automatically close a circuit due to a mechanical load. Fields of application include door locks and microwave ovens. In the latter case, the microswitch ensures that the power supply to the device is only guaranteed after the door has been closed. Similar application principles can be found in many other fields.
A microswitch requires only a small amount of physical force to ensure the power supply. Accordingly, they are particularly suitable for applications that are operated with a finger and for systems that measure small pressure differences in air or gas.
Structure of a microswitch
In many cases, a microswitch is a spring-loaded version with a lever. A spring mechanism ensures that the switch returns to its initial position after an operation.
In most cases, a microswitch has three connection points: C (Common), N/O (Normally Open) and N/C (Normally Closed). Depending on the switching function, these points are switched differently. With a toggle switch, one of the two connection points, also called terminals, N/O or N/C, is always supplied with power. Microswitches also have N/C and N/O contacts. A normally closed contact is the term used for a closed contact in the idle state: it is opened, for example, when actuated. Here the C terminal is connected to the N/C terminal in idle state and this connection is interrupted when switching. With a normally open contact, on the other hand, the contact is only closed during the switching process. In this case, C and N/O terminals are connected when actuated.
Depending on the variant, microswitches have different connection terminals. They can either be plugged directly onto a breadboard, soldered onto a circuit board or attached using a screw mechanism. Robust materials are used as materials that reliably withstand mechanical and thermal influences. These include thermosets, fiberglass and rubber. All in all, microswitches have a particularly long service life with several million switching cycles.
Further construction methods of microswitches are so-called snap-action switches or detector switches.