Improvements in the Application of Telephones to Electric Bell Systems.
Year: 1895

page_text: Date of Application, 17th June, 1895
Complete Specification Left, 10th Jan., 1896-Accepted, 17th Jan., 1896
Improvements in the Application of Telephones to Electric Bell
Systems.
FREDERICK HODGSON Electrician 8 Agincourt Road Hampstead N.W.
GEORGE ALFRED EDWARDS, Electrician 13 St. George's Street, Peckham S.E.
do hereby declare the nature of this invention to be as follows:-
The object of this our invention relates to being able to communicate to, and
from, press buttons and indicator, for signalling and speaking purposes, without the
aid of extra wires or batteries at the press buttons.
At the press button of an electric bell system, we connect a telephonic apparatus,
with a condenser or resistance to the two wires, so that practically there would be
little, or no, current passing from batteries, when the apparatus is at rest.
At the indicator of an electric bell system, we connect a plugging arrangement;
and a telephonic apparatus fitted with plug and necessary battery power, or inductive
generator, for actuating call arrangement at outlying stations.
Intercommunication can be accomplished by usual known methods.
Deted 17th day of June 1805
FREDERICK HODGSON.
GEORGE ALFRED EDWARDS.
Improvements in the Application of Telephones to Electric Bell
Systems.
We, FREDERICK HODGSON, of 8, Agincourt Road, Hampstead, in the County
of Middlesex, Electrician, and GEORGE ALFRED EDWARDS, of 13, St. George's
Street, Peckham, in the County of Surrey, Electrician, do hereby declare the
nature of this invention 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 improved means applicable to electric-bell systems or
circuits, whereby such systems or circuits may be utilized for telephonic
communication and for signalling in both directions; the employment of an
additional wire, battery and bell for effecting such modes of communication being
rendered unnecessary, and the expense incidental to their supply and installation
saved.
In the accompanying drawings, we have illustrated diagrammatically three modes
of applying our invention;
Fig. 1 showing an arrangement in which a condenser is employed at the
out-station

page_text: Fig. 2 an alternative arrangement in which an open resistance is used, and
Fig. 3 a modified arrangement, a closed resistance being employed at the out-
station and a galvanometer or relay at the indicator-station.
are
"cut out
"
Referring to Fig. 1, in which is illustrated one mode of applying a telephone
service to an electric-bell circuit according to our invention, when the line is
required for telephonic communication or for signalling to the out-station O, the
bell with its battery and the indicator pertaining to the signalling or call-line wire
of the circuit at the indicator-station I by means of a plug herein-
after more particularly referred to. In the circuit at the out-station are arranged
in suitable positions a switch a, a condenser b, a transmitter c and a receiver d;
same being so disposed that when the receiver is at rest on the lever of the switch a
the latter makes contact with the stud a¹ (as showu) and thereby establishes
electrical connection with one side of the condensor 6; the other side of the
condenser, meanwhile, being in series with the receiver d and in connection with
the battery-line-wire a°. The line wire a* is led to the switch a. The system is
now in condition for transmitting a call to the out-station. On depressing a press-
button e arranged across the circuit at that station, such circuit is close and the
current permitted to pass for the purpose of actuating the indicator and ringing
the bell at the indicator-station I. In the circuit at the indicator-station, a pair
of metallic springs or clips are arranged for the introduction between then of a
suitable, plug. These springs or clips f, previous to the introduction of the plug,
are in electrical contact, so that on the press-button -e, at the out-station, being
depressed, a call or signal is given at the indicator-station by the aid of the bell
and indicator in the usual manner. The requisite call and reply having been given,
the receiver d, at the out-station O, is removed from the switch-lever a, which
operation has the effect of automatically establishing contact between the switch a
and the stud a²; the latter being in series with the transmitter c and the receiver a
and in connection with the battery-line-wire aº. Through communication having
been established between the instruments at the indicator- and out-station by the
introduction of the plug f¹ between the springs or clips f, and the receiver removed
from the switch-lever at both the indicator- and the out-station, telephonic speaking
can be accomplished in the usual way; the call-bell with its battery and the
indicator being cut out of the circuit. The plug is so constructed as to establish
electrical connection with the operator's telephonic and signalling instruments and
the line-wire a*, but to disestablish the connection with the line pertaining to the
indicator and call-bell.
To effect a call at the out-station O, the plug f' is first introduced between the
springs or clips f. A transmitter i and a receiver i¹, the respective diaphragms of
which are preferably arranged parallel and close to one another, are disposed so
that the transmitter i is in the primary circuit of an induction coil k, which derives
its current from the battery B, while the receiver is placed in the secondary
circuit. Both these circuits are open until connection is established at the
contacts, pertaining to the press-button L, whereupon both the respective
circuits are simultaneously closed." The primary circuit of the induction coil k is
now in series with the transmitter i, battery B and contact 1. The secondary
circuit of the coil k is connected in series with the receiver ', contact 1, plug f',
springs, line wire a* and out-station switch a, stud a' and with one side of the
condenser ; the other side of the condenser being connected in series with the
receiver d and terminating with the battery-line-wire a to the opposite end of
the coil k. The two circuits being closed, with the aid of the currents generated
by the induction coil k, a musical sound is produced by reason of the peculiar
disposition of the diaphragms pertaining to the transmitter i and the receiver ;
the said musical sound being repeated in the receiver d at the out-station O with
sufficient intensity to attract attention. Should a louder call .be required at the
out-station than that which is produced by the receiver d, a bell may be arranged
in the circuit and be connected in series with the condenser b, or this bell may be
connected with an induction coil, one circuit of the latter being connected in series

page_text: Or a
with the call-circuit, while the other is connected directly with the bell.
condenser may be employed, arranged with moveable coatings so that they are
attracted when charged until they touch each other and so close a bell-circuit.
According to an alternative arrangement, illustrated in Fig. 2, in the out-station O,
an open resistance takes the place of the condenser shown in Fig. 1, and, in
the indicator-station I an intensifying induction coil with its interrupter 4* is
inserted in substitution for the transmitter i and the receiver of the previously
described arrangement. In effecting a call to the indicator-station, the press-
button e at the out-station O is manipulated as before explained. The plug fis
then inserted between the springs fas herein before described, with the result that
the indicator and call-bell with its battery are cut out of the circuit, and electrical
connection established between the out-station and the operator's telephonic and
signalling instruments. When the receiver d is in the position of rest on the
switch-lever a, a call may be given at the out-station by depressing the press-
button L at the indicator-station; currents of sufficient strength, or electromotive
force, being generated in the induction coil * to effect a passage over the open
resistance and convey the call by repeating the sounds, caused by the vibrations
of the interrupting armature of the intensifying induction coil k*, which are
emitted from the receiver d. The requisite call and reply having been given, and
the receiver having been removed from the switch-lever at both the indicator- and
The
out-station, the system is now in condition for telephonic communication.
open resistance may consist of two silk-covered wires twisted together, as in a
lightning protector. Or it may comprise two pieces of conducting material
arranged in close proximity to, but not actually touching one another; same being
by preference enclosed in a vacuum.
The arrangement illustrated in Fig. 3 is similar to that of Fig. 1, a closed
resistance 6, in the out-station O, being substituted for the condenser (Fig. 1).
At the indicator-station I, the indicators are divided between two circuits and each
circuit is connected to one of two coils of a galvanometer or of a relay. The
current passing through the closed resistances and lines is ineffective to operate
the indicators or to disturb the balance of the galvanometer; but on depressing the
press-button e at the out-station, the full current passes through the line-wire a a
and actuates the indicator. At the same time, the increased current passing
through one coil of the galvanometer causes the needle or contact-maker of that
instrument to be attracted and a local bell-circuit to be brought into action, the
desired call resulting. Without such an arrangement, it will be apparent that,
although the current passing the closed resistance 62 would be insufficient to ring
a bell, a current of sufficient strength would pass to continuously ring the bell in
the event of several or many circuits being connected up. The battery-line-wire a°
and the line-wire L' lead to another out-station. For the closed resistance, we
prefer to use a fine carbon filament, but other substances may be employed.
Although we have spoken of a condenser in reference to Fig. 1, it must be
understood that by a condenser we mean any arrangement of conductors and
dielectrics that will accomplish our object, i.e., working a telephone call without
allowing the battery current to flow through the circuit.
Having now particularly described and ascertained the nature of this inven-
tion and in what manner the same is to be performed, we claim :—
1. In an electric-bell system utilized for telephone purposes, the employment of
a condenser, substantially as herein described, and whereby the flow of current
through the call circuit is arrested whilst the circuit is out of use.
2. In an electric-bell system utilized for telephone purposes, the employment of
a resistance, substantially as herein described, and whereby the flow of current
through the call circuit is avoided or retarded whilst the circuit is out of use.
3. In an electric-bell system utilized for telephone purposes, the employment of
the telephoue-receiver at the out-lying station as a call," substantially as herein
described.
66

page_text: 4. In an electric-bell system utilized for telephone purposes, the employment of
an induced current to operate the call at the out-lying station, substantially as
herein described.
Dated this 0th day of Tonu 1906