Vol. EE Reference
Chapter 9 Circuit Schematic Symbols

Switches, Hand Actuated

A switch is an electrical component that can “make” or “break” an electrical circuit.

Hand actuated switch means that the switch is operated manually using physical contact.

Above are schematic symbols of the most common hand actuated switches. 

Single Pole, Single Throw (SPST) is a simple on-off switch, the two terminals are either connected together (normally closed) or disconnected from each other (normally open).

Double Pole, Double Throw (DPDT) is equivalent to two(2) SPST switches but it is neither normally closed nor normally open. 

Push button is another type of hand actuated switch, like SPST, it is either a normally closed or normally open switch.

Single Pole, Double Throw (SPDT) is a simple break-before-make changeover switch. Four Pole, Double Throw (4PDT) is similar to four (4) SPDT switches.



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