Re: OT, proper phone wire question?/Twists & Guage ?
----- Original Message -----
From: "lee" <lnx@alltel.net>
To: <debian-user@lists.debian.org>
Sent: Wednesday, November 26, 2003 17:30
Subject: Re: OT, proper phone wire question?/Twists & Guage ?
On Tuesday 18 November 2003 15:36, Derrick 'dman' Hudson wrote:
>
> Why are twists so important and why do the faster technologies need
> more twists in the cable? As an electric signal varies along a pair
> of wires, a magnetic field around the wires is created and then
> collapses. This field will induce a current in another wire that
> passes through the field. That induced current is "noise", because it
> intereferes with the electric current (signal) that is intentially
> being sent over that wire. Twisting the wires reduces the size of the
> generated magnetic field, and also reduces the cable's ability to pick
> up a signal from a nearby magnetic field.
>
> For voice-grade telephone, no twists are needed most of the time. For
> better signalling and less noise, get more twists. Using Cat 0 or Cat
> 3 should be fine, but the Cat 3 will cost more money. You *may* have
> noise problems with Cat 0 which will hurt your ability to connect,
> maintain a connection, and will limit transfer rates. Basically "more
> is better" when it comes to twists, but also "more costs more". It's
> up to you to find the desired return-on-investment for cable quality.
>
> HTH,
> -D
Thank you very much for the discussion on twists, I have a question..what
about actual wire size..cat 3 and 5 are usually 22 or 24 guage..suppose one
was to use say 18 guage speaker wire..it's twisted(like cat), it's
unshielded(like cat)..but a bit larger..less resistance is my
thinking..where
am i wrong here..not enuff twists perhaps?
Thank you all very very much for your time..
Lee
The reason for twisting wires is to reduce 'common mode' noise and it
depends on the noise environment that the wire passes through. More twists
mean a wider range of environments can be handled. Since the voltage
induced in both wires is closer to the same amount. If you would like to
experment try connecting one wire of a pair and a good ground to an
oscilloscope and look at the noise. Modern telephones require very little
current to operate properly so 22 to 24 gauge is entirely adequate and
electronics can require much less, if you do not adhere to telco specs.
Therefore I would not expect any gain from 18 guage wire.
My Opinion for what its worth;
Hoyt
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