On Fri, 15 Feb 2008 00:41:08 +0000, The Natural Philosopher
wrote:

Dave Plowman (News) wrote:
In article ,
The Natural Philosopher wrote:
I cannot remember which wires go where though: there will be two signal
and one bell wire..so if you can identify which plug wires to connect to
in the first place..two will have about 50V DC across them, so that's
one way to find them....the bell wire will give you a nasty tingle when
someone rings you, so conncect theh hamster across various pairs and
dial in from yer mobile. When he leaps, that's teh bell wire..
there are only a finite number of combinations to try, and you won't
screw the exchange up. Not sure about the hamster tho..

Problem with older phones is the bells are low impedance with effectively
a REN of several and will likely stop any others in the house ringing. But
there are ways round this.

BUT EVERYONE ON UK.TELECOM.BRODBAND SWERARS BLIND MODERN PHONES DON'T
USE THE BELL WIRE ANYWAY...

Some modern phones use the bell wire, some modern phones don't.
Besides, that is not relevant to the REN. Most modern electronic
phones are high impedance and don't load the phone line with low
impedance bells and electromagnetic earpieces. The ring detection is
done electronically, maybe across the pair, maybe from the ring line,
either way, it has very little effect on the rest of the circuit.


--
Regards, Paul Herber, Sandrila Ltd.
Electronics for Visio http://www.electronics.sandrila.co.uk/