What is the function of DPDT switch?

Adding another pole to the SPDT creates a double-pole, double-throw (DPDT) switch. Basically two SPDT switches, which can control two separate circuits, but are always switched together by a single actuator. DPDTs should have six terminals. A DPDT circuit symbol, and a 6-terminal DPDT rocker switch.

Correspondingly, how does a DPDT toggle switch work?

A Single Pole Single Throw toggle switch connects or disconnects one terminal either to or from another. It is the simplest switch. A DPDT switch works just like two separate SPDT switches attached to the same switch bat.

What is the use of SPST switch?

These terms have given rise to abbreviations for the types of switch which are used in the electronics industry such as "single-pole, single-throw" (SPST) (the simplest type, "on or off") or "single-pole, double-throw" (SPDT), connecting either of two terminals to the common terminal.
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