In message , Roger Mills
writes
In an earlier contribution to this discussion,
The Natural Philosopher wrote:


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...

So? I thought this thread was about *old* telephones - which *do* use the
bell wire when connected to a modular socket - and even when hardwired if
they were not the first in line.

ISTR that old bells had an impediance of 1k ohms - thus having a REN of 4 -
whereas later ones with a REN of 1 had an impedance of 4k ohms. So,
basically, you need to wire a 3k ohm (some say 2.2k - not quite sure why)

2.2k being a preferred value of a power series perhaps



--
geoff