Automatic Electrical Ring-off Appliance for Telephone Stations.
Year: 1899

page_text: Date of Application, 11th May, 1899-Accepted, 24th June, 1899
COMPLETE SPECIFICATION.
Automatic Electrical Ring-off Appliance for Telephone Stations.
We, SIEMENS BROTHERS & Co., LIMITED, of 12, Queen Anne's Gate, West-
minster, in the County of London, Electrical Engineers, do hereby declare the
nature of this invention, (as communicated to us from abroad by Siemens &
Halske Aktien Gesellschaft, of Markgrafen Strasse 94, Berlin, S.W., Germany,
Electrical Engineers,) and in what manner the same is to be performed, to be
particularly described and ascertained in and by the following statement:-
This invention relates to an electric ring-off appliance whereby the ring-off
signal given automatically on hanging up the subscribers telephonic receiver.
The action of the appliance is such that during the speaking of two subscribers
there is introduced into their circuit a polarisation cell while at the switch board
of the telephone exchange there is connected between the point of the peg and
neck of the peg of each peg, a ring-off device, such as a galvanoscope and
battery, so that during the speaking the said cells prevent the passage of the
continuous current and consequently also the movement of the galvanoscope.
If, however, the telephone receiver be hung up at the one station, the correspond-
ing cell is cut out by means of the hook switch, and the battery current effects
a deflection of the galvanoscope whereby the attendant is informed of the ter-
mination of the speech.
As however it frequently occurs that the called subscriber hangs up his tele-
phone before the speaking is finished, in order either to call another person or
to refer to some matter, a third polarising cell requires to be introduced at the
telephone exchange in the point lead of the test peg, which is always connected
to the peg of the called subscriber, so that this circuit is permanently closed
against a continuous current whether the subscriber hangs up his telephone or
not.
The invention is applicable both for single and double wire circuits, as also
to a combination of both, as will be seen from the accompanying diagrammatic
drawing.
a and b are the telephones of two subscribers, of which a is connected by a
single wire circuit and 6 by a double wire circuit with the central station, c are
the ordinary hook switches d the call signal; e and f are the polarising cells
which can be put in or out of circuit by the hook switch.
In each of the switch boards of the telephone exchange is the calling peg
and the test peg. The connecting lead of the two peg necks has a branch
lead in which is included a battery element i and a galvanoscope k, and which
is connected with the two contacts and m of the speaking switch, with which,
in the position for through communication the peg points are connected through
the contact springs no which then have the position shewn in dotted lines.
is also a polarising cell which, as above stated, serves for only enabling the call-
ing subscriber to ring-off.
If now a connection between the two subscribers be established the pegs g and h
are inserted, as indicated by the dotted positions. and the contact spring m

page_text: are upon the contacts 1 m. The telephones are lifted off the hook switches
whereby the call signal is cut out and the polarising cells ef are included. The
speaking current then passes through the cells as follows, for instance, from
hook switch c of subscriber a through line wire q jack spring r point of peg g
contact spring o contact m, polarising cell p contact 1, spring n, point of h jack
spring s line wire t hook switch c and telephone of subscriber 6, polarising cell f
socket lead u neck of h neck of g, socket lead v central station earth, subscribers
station earth, and thence through cell e and telephone back to the hook switch c
of a.
As a battery element i and ring-off indicator k are included between the connect-
ing lead of the two peg necks on the one hand and the connecting lead of the
two contacts I m which connect the two peg points by the springs no, on the
other hand, a current might pass from the element through a subscribers
apparatus and actuate a ring-off signal, if the polarisation cell were not included
in this circuit and did not stop the battery current.
The passage of the current takes place as follows:-
For example from the +-pole of element i through ring-off signal k contact m
spring o point of g spring r lead q hook switch c, telephone, polarising cell e,
subscribers earth, central station, earth, socket lead v neck of g and back to
pole of . But as the polarising cell does not allow the passage of a continuous
current, the ring-off signal cannot be actuated. Only after the telephone has
been hung on the hook switch will the cell e be cut out by the latter, as shewn
in full lines on the drawing, and the current from i can then pass through the
call signal and actuate the ring-off signal k.
If were omitted, the above action would also be effected by the circuit
passing through peg and subscriber b's apparatus; if however it be desired
to prevent this for the above stated reasons, the polarising cell p is introduced
at the central station, between the ring-off signal and the point of the test peg,
whereby the passage of a ring-off current in this direction is permanently
prevented.
Consequently, according to requirements, the ring-off signal may either be
actuated by both subscribers or, by the addition of the cell p, this may be limited
to the one subscriber.
Having now particularly described and ascertained the nature of this inven-
tion and in what manner the same is to be performed, we declare that what we
claim is:-
1. Appliance for effecting an automatic electric ring-off at a telephone exchange
consisting in the inclusion in the telephone circuit or parallel thereto of a low
potential and a ring off signal controlled by a polarisation cell at the subscribers
station which is alternately put in and out of circuit by the action of the tele-
phone switch, substantially as described.
2. In the automatic ring-off appliance referred to in the first claim, the arrange-
ment whereby on connecting the potential and the ring-off signal in parallel, the
ring-off circuit passing through the test peg is permanently closed by a polar-
ising cell, so that the ring-off signal can only be given by the calling subscriber,
substantially as described.
thin 11th dow of M 1800