Jim Redelfs wrote:
Ralph Mowery wrote:

US standard ring voltage is 90
volts AC at 20 Hz unless you're on a party
line and the ringers will be of the type
that are filtered to ring at different
AC frequencies.

Multi-party service did NOT use "filtered ringers". I don't believe
such a thing ever existed.

On two-party service, the ringing current is sent down one "side" or the
other of the serving pair. At the station, the phone's ringer was
connected to either the ring or tip side of the pair and the other side
to ground. As mentioned earlier here, most station wiring was, for
DECADES, three conductor. The third conductor was to provide a ground
for partyline use.

A private line-wired set, "illegally" connected to a 2FR, would ring for
ALL calls because its ringer was wired ACROSS the pair instead of as I
described above.

Really OLD, multi-party installations? That was even more complicated.

A 4FR (four parties on the same cable pair): One party on the ring side
was assigned a LONG ring, the other party was assigned two, short rings.

The same held true for the two parties whose phone ringers were wired to
the TIP side of the pair.

I looked this one up in an electrical engineering reference ca. 1968.

In addition to what you wrote above there was tip-to-ground with
positive and negative ringing and similar ring-to-ground positive and
negative ringing. That gives 4 party full selective ringing.

The text refers to frequency selective ringing. What I remember is the
ringers were mechanically or electrically resonant at different frequencies.

I have no idea how common either of these schemes were. They require
different ringers (frequency selective) or added cold cathode tubes (+/-
ringing).

--------------------------------
Thanks for all the great phone info (this thread and all the others).
Tidbits like construction of quad cable to eliminate crosstalk are
priceless.

--
bud--