RE: Reversing phone line polarity, was Re: windows calle r id and answermachine solution

["Keith Doxey" <ukha@xxxxxxx>]

Hi Robert,

Look at http://www.diyha.co.uk/telephones/pots.html
and http://www.diyha.co.uk/projects/silent_phones.html

if the site is up and running. It is suffering from router problems at the
moment :-((

The incoming line is A & B
The bell wire is connected to B via a capacitor
The bells connect to A & Bell Wire

Reversing A&B after the socket effectively connects the bells across
the
capacitor B & Bell. This leaves no connection to the A wire so no
return
path for the ringing.

If you do the revesal between sockets that have phones connected to them
you
end up putting two bells in series across the line. The usual effect is the
line is permanently busy and if the phones have electronic ringers instead
of bells they will squeal continuously.

Keith

> -----Original Message-----
> From: Robert Chasmer [mailto:robert.chasmer@xxxxxxx]
> Sent: 01 June 2001 14:28
> To: 'ukha_d@xxxxxxx'
> Subject: RE: Reversing phone line polarity, was Re: [ukha_d] windows
> calle r id and answermachine solution
>
>
> Keith Doxey [mailto:ukha.diyha@xxxxxxx] wrote:
> > Cant see why it would work unless the CallerID unit was polarity
> > sensitive which is bad design as telephone lines often get
reversed
> > when cables are worked on.
> >
> > If you do try reversing the line, you need to do it at the main
> > incoming point.
> >
> > REVERSING THE LINE BETWEEN SOCKETS WILL CAUSE BELLS TO RING
> > PERMANENTLY.
>
> The fun I had the other day.  I've recently been retro fitting Cat 5
at
> home, and finally got my Patch Pannel installed.  I ran a cable from
my BT
> master socket (one of those big boxes where you attach extensions
> to a sort
> of fited plug socket pannel).
> The other end I attached to 8 of the ports on the patch panel.  This
would
> allow me to patch the phone line into any rooms when needed.
>
> Once it was all finished I noticed that none of the phones
> connected via the
> patch panel were ringing.  Except our new Caller ID cordless phone.
>
> So I started investigating assuming that I'd somehow miss wired the
bell
> wire.  After a few hours and a lot of trial and error moving the
> bell wire,
> checking it wasn't broken, listening to all the phones ringing, it
still
> wasn't working.  I discovered that one of the other OLD
> extensions was also
> a master socket, so I removed that thinking that could be the problem,
but
> no.
>
> As a last ditch attempt I swapped over the two main line wires
> comming from
> the BT master to the patch pannel.  Hey presto everything was up and
> running.
>
> So a few questions:-
> * Why does the polarity of the line wire matter after its been
> through a BT
> master socket?
> * Why did the Caller ID phone work? (I pressume it must detect
> the ring from
> the line wires)
> * Does having addtional master sockets on the extension matter?
>
> --
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>  / /__/ / / /  / / / /  / / _____/ / Rob Chasmer, MMT Computing
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>
>
>
>
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