[Tfug] Yet another poser

[George Cohn]

jblais wrote:

> 
> I guess this is how X-10 stuff works -
> I also remember an old house where we lived, where only one phone wire came
> into the house, the circuit was closed through ground, and from the
> grounding block there were 2 wires through the house.
> 
> joe
>

X10 is a carrier current system, the signal is superimposed on the A/C 
power line.  If you go to http://www.X10.com you might be able to find 
the specs.  I use X10 throughout my house, been using it since BSR 
originally developed the first commercial product.

Telecom is different.  The single pair, green = tip, red = ring, was not 
grounded.  However, they did go through a lightning arrestor and it did 
have a ground wire.  Sometimes they use white = green and blue = red.

BTW, the positive or red side is signal ground at the central office. 
Conceivably they could have used just one wire but it potentially would 
be very noisy due to the resistance of "ground" at the customer premise.

The terms tip and ring come from the old cord board days when the 
operator had to plug in a patch cord to connect parties.  The cord 
actually had three contacts, tip on the very end, ring was next, then 
sleeve was closest to the cord.

In the old days of party lines, IE more than one subscriber on a pair, 
they often used various methods for the bell.  On one party it might be 
connected to tip and ground, on another ring and ground, on a third it 
might be bridged across tip and ring, and they even used harmonic 
ringers that responded to different frequencies for 4 to 8 party lines.

Imagine trying to do dial-up on an 8 party line!  ;-)

George Cohn