On 16 Jan 2006 11:25:38 -0800, "Larry Bud"
wrote:


mm wrote:
On Mon, 16 Jan 2006 12:02:15 GMT, (Beachcomber)
wrote:


Three way (and four way) switches are mis-named but no-one ever
bothered to change the term for a better understanding of common
electrical use. A three way switch is more correctly termed a Single
Pole Double Throw switch (SPDT). Why then, is it called a three
way switch? Because it has three terminal screws on it?! Very
strange.

LOL. Good point.

'm sure whoever called it "3-way" first knew exactly how it worked. I
wonder what he was thinking.

It's 3-way because there are 3 different ways the light can be on.

S #1 "up" S #2 "Up"
S #1 "up" S #2 "down"
S #1 "down" S #2 "up"


This would be a logical OR (switches in parallel). Not a 3-way
connection. With this S#1 "up" would make S#2 irrelevant. This does
not happen with a 3-way (XOR function) where each switch is always
active.



or Switch #2 "

--
Mark Lloyd
http://notstupid.laughingsquid.com

"Democracy is two wolves and a lamb voting on what
to have for lunch. Liberty is a well armed lamb
contesting the vote." - Benjamin Franklin