What does SPDT stand for in a 19mm SPDT micro switch

In a 19mm SPDT micro switch, "SPDT" stands for Single Pole Double Throw. A micro switch is a small, sensitive switch that can be used in a variety of applications. Some micro switches are designed with a snap action mechanism, which means they change state quickly when actuated, providing a distinct tactile feedback. These are often referred to as snap action micro switches. Micro limit switches, a type of micro switch, are used to detect the presence or position of an object.

An SPDT switch has three terminals: the Common (COM), Normally Open (NO), and Normally Closed (NC). By default, the COM terminal is connected to the NC terminal. When the switch is actuated, the connection shifts from NC to the NO terminal. This differs from a Single Pole Single Throw (SPST) switch, which has only two terminals (COM and either NO or NC). An SPST switch can only control one circuit and has a simpler on/off function. A Double Pole Double Throw (DPDT) switch, on the other hand, has six terminals and can control two separate circuits simultaneously, with each pole having its own COM, NO, and NC terminals. The SPDT configuration in a 19mm micro switch offers more flexibility in circuit control compared to SPST, while being simpler than the DPDT for applications that only require controlling one circuit with two possible states.