Re: gEDA-user: spdt, spst

[Dave McGuire <mcguire@xxxxxxxxxxxxx>]

On Jan 19, 2005, at 1:31 PM, Karel Kulhavy wrote:
> > SPST ..... Single Pole, Single Throw
> > SPDT ..... Single Pole, Double Throw
>
> What does "pole" and "throw" mean? I know just what north and south 
> pole is.
> And also telephone pole.

  Picture a switch with three connections, labeled 1, 2, and 3.  At any 
time, electrical contact is made either between 2 and 1, or between 2 
and 3, depending upon the direction of the switch handle.  This would 
be an SPDT switch...One "pole"...one movable contact, and two 
"throws"...two positions in which that contact can reside.

  Like this:

  /---\                       /---\
  o    o    o            o    o    o
  1    2    3            1    2    3

  Get it?

          -Dave

--
Dave McGuire              "I've watched Harley people throw up
Cape Coral, FL                      on the ceiling."    -Krissi