A New or Improved Method of Connecting Electric Telephonic Apparatus as a System.
Year: 1899

page_text: Date of Application, 2nd Feb., 1899
Ath Awe 1000 Accented 21st Oct
1800
PROVISIONAL SPECIFICATION.
A New or Improved Method of Connecting Electric Telephonic
Apparatus as a System.
We, FRANCIS GEORGE BELL, Electrician, and MAX BYNG, Electrical Engineer,
both of 69-71-88-92, Queen Victoria Street, in the City and County of
London, do hereby declare the nature of this invention to be as follows:-
Our invention relates to a new or improved method of connecting electric
telephonic apparatus as a system, and has for its object the use of a single
central source of current, such as a battery, in a part of the circuit, so that
two or more telephone sets with an induction-coil may be operated thereby.
In order that our invention may be the better understood we have appended
the accompanying sheet of drawings in which Figure 1 represents a diagram of
connection in which the battery in included in one circuit. Figure 2 is a
similar diagram showing the battery included in the line circuit. Similar letters
of reference indicate corresponding parts in both views.
In carrying our invention into practice we couple the primary (or what is
ordinarily known as the series coil) P in series with the microphone M, and in
parallel with the secondary coil s, the receiver R being in series with this
member of the parallel circuit in the same manner that M is with P, as afore-
said. A battery, or other source of electric current B is connected to the
parallel circuit ff by the conductors e e, and also operates the distant apparatus
through the line wires c.
Here, again, the microphone M is placed in series with the primary coil P¹
and the receiver R¹ in series with the secondary coil s¹, both branches being con-
nected in parallel as shown. In this case, there is a closed circuit, with the
combined resistances of the secondary coils s s and the microphones M M plus
the coils of the receivers R R¹ the essential feature being in that the primary
and induced currents are carried by the same conductors e, from one battery B,
or like source of current, which may be two or more sets of apparatus according
to its power.
Figure 2 illustrates a modification of arrangement in which the battery or
other source of current B is included in the line circuit c, and operates the two
sets of primary P shunt s microphone M and receiver R, and also P¹¹ M¹ and R¹.
From the foregoing description it is obvious that from the battery B or the
equivalent thereof, the line wires c may be extended on each side to carry sets
of telephonic apparatus connected in parallel to any number within the range
of the power relatively to the resistances. According to Figure 1 the battery or
source of current B is at one end of the system, which may be extended within
its range in a similar manner. A separate signalling system may be employed
in combination with this device, employing the ordinary line wires c or another
and distinct circuit.
FREDK. WALKER,
73, St. Stephen's Road, Upton Park, London, E.,
Agent for the Applicants.

page_text: A New or Improved Method of Connecting Electric Telephonic
Apparatus as a System.
We, FRANCIS GEORGE BELL, Electrician, and MAX BYNG, Electrical Engineer,
both of Nos. 69-71-88-92, Queen Victoria Street, in the City and County of
London, 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:
Our invention relates to a new or improved method of connecting telephonic
apparatus as a system, and has for its object the use of a single central source of
current such as a battery in a part of the circuit, so that two or more telephone
sets with induction coils may be thereby operated.
In order that our invention may be the better understood, we appended a sheet
of drawings to our Provisional Specification in which Figure 1 Sheet 1 repre-
sents a diagram in which the battery is included in one circuit. Figure 2 is a
similar diagram showing the battery included in the line circuit. To our Com-
plete Specification we have appended two sheets of drawings which correspond
therewith and are consecutively lettered. Figure 3 shows three stations and a
central, with diagrammatic illustration of the system of connecting and wiring
Figure 4 shows a single station with connections.
In carrying our invention into effect we couple the "primary" (or what is
ordinarily known as the series coil P in series with the microphone M and in
parallel with the secondary coils, the receiver R being in series with this
member of the parallel circuit in the same manner that M is coupled with P
as aforesaid.
A battery or other source of electric current B is connected to
the parallel circuits of fl by the conductors e e¹ and also operates the distant
apparatus through the line wires c. The microphone M is placed in series with
the primary coil P¹ and the receiver R¹ in series with the secondary coil s¹ both
branches being connected in parallel as shown. Thus, there is formed a closed
circuit with the combined resistances of the secondary coils ss and the micro-
phones M M plus the coils of the receivers R R¹, the essential feature being
in that the primary and induced currents are carried by the same conductors e
from one battery B or like source of current, and may constitute two or more
sets of apparatus according to the power thereof.
Figure 2 illustrates a modification of the foregoing arrangement in which the
battery or other source of current B is included in the line circuit c and operates
the two sets of primary coils P P¹ shunt s microphone M, receiver R, and s¹ M
and R as shown.
We use any type of the ordinary component parts of a telephone, viz.-
microphone, receiver and induction coil, and referring to Figure 2 it will be
seen that the primary coil P of the induction coil is connected in series with
the microphone M and forms one branch of a circuit, a second branch thereof
being formed by the secondary coils of the induction coil being connected in
series with the receiver R. If two telephone sets are so arranged and con-
nected by the line wire L and return wire L' including a battery B in circuit,
as shown by Figure 2, the speaking communication is both loud and clear.
The application of this principle is wide and diverse, such as "police calls"
"
fire calls communications along train or tramway tracks and the like..
Referring to Sheet 2 appended to our Complete Specification, Figure 3, the
system of arranging the instruments and connecting them up, so that any one
of a number of substations can call or converse with a central station is shown.
At each station an oblong metal case C C C is fitted with an induction coil
66
•

page_text: with a primary coil P and secondary coils and is coupled up to a hand combina
tion micro-telephone as shown by C, and C and C are presumed to be smilarly
fitted but this arrangement is not necessarily shown repeated-a flexible con-
ductor or conductors connect the coil with the micro-telephone combination.
On the containing case C C or C" but insulated therefrom, two connecting
terminals L L are fixed, being separated electrically from the case by a sheet
of mica a a¹. The connections of station C are arranged as follows. The line
wire enters by terminal L to the lever k of the hand combination. The return
wire enters by terminal L¹ and passes through the parallel circuit with
primary coil P and microphone M in one branch; and secondary s and receiver R
in the other, to the contact 1. At the central station we employ a relay ga
local belli, receiver R, induction coil s P, coupled as shown, and an automatic
switch hook of the ordinary type operated by the receiver R being hung
upon or removed from it, and a battery B which practically operates all the
stations in the circuit. The switch j is shown in the midway position between
the contacts f and b. But the automatic connection of the switch j is arranged
so that the weight of the receiver R causes j to be in contact with f, when R
is on the hook. When R is removed, the weight or a spring in tension causes j
to make contact with b. When the receiver R is upon the hook switch j the
circuit is as follows, that is to say:
From the terminal L by the wire d to the relay g, through these coils and
thence to the switch contact f, and the switch hook j, to terminal C, which is
the carbon of the battery. Then through the battery to terminal z and thence
to L'. If now L L are electrically connected, the armature of the relay g
will be attracted by the magnet coils so as to make contact with h thus closing
the local bell circuit, in this manner; through C which is the battery carbon,
switch contact f relay armature contact point h; to bell i to terminal B Z
and thence to the third or fourth zinc element of the battery from the carbon
end thereof. So long as the terminals L L¹ are connected and the receiver on
the hook switch j, the bell i will continue to ring, being operated by as many
cells of the battery B as we may prefer to use.
We may as an alternative employ a separate bell battery, and also may in
some cases dispense with the relay, using a direct current from the line wires.
If instead of shortcircuiting L L' we connect two wires thereto, and extend
them for any distance, insulating one from the other, and connect the apparatus
shown at C Figure 3 with terminal L on one wire and L' on the other, the
relay at central is not active until key K of telephone is pressed when a circuit
is completed, through the parallel circuits P and M in one branch and s and R
in the other, and a call may then be given to the central station. In order to
reply the attendant raises the receiver R from the hook j, and holding, it to his
car replies by speaking into the microphone M.
Now to follow the circuit of two stations commencing from the central at L,
which is connected to L of station C switch lever contact stud z where the
circuit is divided, one branch passing through R and s, the other passing
through M and P where they again join and pass to terminal L¹ thence along
return wire to L' at the central station. Then from terminal Z (zinc of battery B)
through said battery to carbon terminal C, hook switch j, contact b, from which
the circuit is again divided into two branches, R and s and M and P respectively,
completing the circuit at L which was the starting point.
It is obvious that when the lever k at station C is pressed and the receiver R
at the central station is off the hook switch j, the circuit is relatively the same
as shown by Figure 2, Sheet 1.
We do not confine ourselves to any particular form of receiver or transmitter
or the adjuncts thereof, but may adapt the whole device to the "feeder" pillars
of electric traction systems, or to any kind of device which may readily be
accessible from the street or pavement.
Figure 4 is a sectional view of one of our stations arranged according to

page_text: our invention as herein described, showing a plug contact X suitably adapted
to allow of spring or plunger contacts w w₁ well w fitting into suitable sheaths
in the box C. This enables the policeman or other official to carry, or have
access to the combined receiver and microphone R, M, the box C forming one
of the stations aforesaid, and the plugs and plug holes wwww being inter-
changeable.
We may in this latter case dispense with the lever switch k since the act of
inserting the plug contacts establishes the required circuit between the line and
return wires.
Referring to Figure 3 at C it will be seen that the conductors are used to
connect the hand combination R T with the induction coil s P in the case C,
and in Figure 4, as before described four wires are employed, two being con-
nected to the receiver R and two to the microphone M. That is to say that w¹ wll
are the microphone contacts, and will and w the receiver contacts corresponding
respectively to M M¹ R' R. The sockets ww are connected together so that
the plug X with its contacts w, we will, will may be operative in any position of
insertion, hence the necessity of employing 4 conductors. But we might employ
three plugs and corresponding conductors making a distinctive mark on the
plug and case so as to show the correct method of insertion.
When the 4 way plug is inserted and its circuit established it is identical
with that of sub-station C, Figure 3.
We may use the "hand combination" R, M, as shown, or any other suitable
device, and may carry the line wires to any distance and interpose any number
of substations subject to the battery power available at the central station.
Having now particularly described and ascertained the nature of our said
invention we declare that what we claim is:-
First. In an electrical telephone system the method of and means for employ-
ing a central station with a battery or like source of current, with a number of
substations, included in the circuit, substantially as herein described and shown
by the drawings hereto appended.
Second. In an electrical telephone system the employment and
use of a
switch which by making one contact closes both primary and secondary circuits
of the induction coil or coils, substantially as herein described and shown.
Third. In an electrical telephone system the method of joining or connecting
the primary and secondary circuits of the induction coil and its adjuncts, sub-
stantially as herein described and shown by the drawings.
Fourth. In an electric telephone system, the method of, and means for adapt-
ing a single contact switch movement which whilst making contact closes the
calling signal circuit, and also closes the primary and secondary circuits of the
induction coil, substantially as herein described and shown by the drawings.
.
Fifth. In an electric telephone system, the arrangement of a plug, trans-
mitter and receiver, fitting any substation with connections substantially as
herein described and shown by Figure 4 of the appended drawings.
Sixth. In an electric telephone system the method of and means for allowing
for the reversibility of the plug contact referred to in the preceding claim, in
which four contacts are used substantially as herein described and shown by
the drawings.
D
800
•
1000
FREDK. WALKER,
73, St. Stephen's Road, Upton Park, London, E.,
Agent for the Applicants.