S

SECOND s
The second is the basic unit of time. It is defined as the length of time taken for 9192631770 periods of vibration of the caesium-133 atom to occur.
The caesium clock.

SEMICONDUCTOR
A semiconductor is an electronic conductor with a resistivity between metals and insulators. The term 'solid state' refers to semiconductor components.

SHIELDING
Imposing a metallic barrier to reduce the coupling of undesirable signals, such as in a shielded cable that is necessary in multiplexing, or domestically in hi-fi connectors.

SINGLE POLE SINGLE THROW
See Switching

SOLENOID
An electrical relay that enables a low current control circuit to switch a power circuit of higher amperage.
Conventional solenoids are electromechanical, involving an electromagnetic coil, but electronic solenoids are also available.
Cole Hersee manufactures both types: see our interactive catalog.

Electromechanical solenoid M-449-04


Electronic solenoid 48785

STRESS
An external force applied to a component or assembly that tends to damage or destroy it.

STINGER
Trucker's poetry for a trailing tag axle that is also liftable. See AXLE

SWITCHING
Using an electrical or electronic component (a switch) to transfer current from one route to another. In its simplest form (On -Off) to make or break a circuit.
Common types are:
Single Pole Single Throw SPST
Single Pole Double Throw SPDT
Double Pole Single Throw DPST
Double Pole Double Throw DPDT

SPST switches control a single wire circuit


SPDT switches control two single wire circuits, allowing only one circuit to be energized at a time


DPST switches control two circuits simutaneously. They act as two switches actuated by a single lever


DPDT switches control four circuits, allowing only two circuits to be energized at the same time