On 10/30/2013 07:11 PM, Arfa Daily wrote:


"Jerry Peters" wrote in message
...
Arfa Daily wrote:


"dave" wrote in message
...
On 10/28/2013 02:43 PM, John Robertson wrote:
On 10/28/2013 12:57 PM, William Sommerwerck wrote:
If anyone is still confused, look at page 2 of this document.

http://www.alliedelec.com/images/pro...S/70155763.pdf





ON - None - ON simply means the DPDT switch only has TWO positions
- ON
& ON with no center spot (OFF). Consider it ON (A circuit) and ON (B
circuit) relative to the commons.

Wouldn't that be 'or' rather than 'and' ??


Think of a 3-Way switch as used in house wiring - but with an extra
pole
- then it is obvious.

John :-#)#


A "3 Way" switch in the wall is an SPDT (the only thing a 3 port
switch
can be.)

Neither of those statements make any electrical sense to me at all. By
"three port" do you mean (more conventionally) "three connection"
?? If
so, then yes, if it's a wall switch, then the only thing it is
'likely' to
be is SPDT, as I have never seen a wall switch with anything other
than two
positions. However, in the case of a toggle switch, it's not strictly
true,
as there are versions with a centre "off" position, and three
connections
also, which is how this thread came about. The "DT" bit is then not
*quite*
the case. It then becomes SPDTCO ...

Arfa

There are 3 position wall switches available. The middle position puts
a diode in series to dim the lights, full-on bypasses the diode. My
parents had one of these switches in their dining room, until the
diode opened, when it was replaced with a regular dimmer.

There are also "4-way" switches available for controlling a light from
more than 2 locations.


Ah, ok. They must be something special to your side of the pond
(assuming that's the left, of course ...) Can't say that I've ever seen
a three position wall switch for dimming, nor a four position one, here.
I've just checked a catalogue that sells electrical fittings, and
nothing like that offered.

Arfa

The imagination is a wonderful thing, but there are a lot of variations
on the wall mounted lamp dimmer, and 99% make my radios buzz.