Improvements in Signalling and Telephonic Systems.
Year: 1891

page_text: Date of Application, 17th Mar., 1891
Complete Specification Left, 17th Dec., 1891-Accepted, 17th Mar., 1892
PROVISIONAL SPECIFICATION.
Improvements in Signalling and Telephonic Systems.
I, JOHN EDWARD KINGSBURY, of 79 Coleman Street, in the City of London,
Manager, (a communication to me from abroad by the Western Electric Company
of Chicago, Illinois, United States of America) do hereby declare the nature of
this invention to be as follows:-
The object of this invention broadly stated, is in a telephone circuit having a
number of stations to arrange the apparatus in parallel circuit or multiple arc,
preferably on a metallic circuit and to be able from any one station to signal
satisfactorily all of the other stations; and also to enable the telephonic trans-
mission and reproduction of conversation between any desired two of the said stations,
to be successfully effected.
To this end the invention comprises the employment of ringer magnets having a
high coefficient of self induction; the discontinuance of the ordinary practice of
including the call sending generator and the ringer magnets serially in the same
circuit when calling; the connection of the said appliance in different and parallel
bridge cross wire or derived circuits of the main line; the ringer magnet bridge
being normally and permanently closed or continuous at all stations; and the.
generator bridge circuit being normally open or discontinuous but adapted to be
closed while sending a call; and the connection of the telephones in a third bridge
circuit at each station this circuit also being open when the telephone is not actually
in
use, but closed in multiple arc with its own ringer magnet and of course with the
ringer magnets of other stations, when in use.
If the line employed were single instead of double the ringer magnets would be
included in a permanently closed earth branch. When the call bells are connected
at a number of stations on one circuit in multiple arc, it is of course required that
call signals transmitted from one station shall ring the bells at all the other stations,
that having signalled and attracted the attention of any given station conversation
may be readily exchanged and that the loudness of the reproduced speech shall not
be impaired or perceptibly diminished by the permanent connections between the
two main wires involved by the presence of the ringer magnets connected as
described at the unemployed stations.
This can best be accomplished by providing call hell electromagnets which have
a high co-efficient of self induction. To construct ringer magnets fulfilling this
requirement the iron cores which are yoked together by an iron heel as usual are
lengthened out and the electromagnet wound with fine wire to a resistance of about
1000 ohms.
When ringer magnets constructed, as above are used, the ordinary mode of
connecting them serially in the same circuit with the generator coils is
impracticable, for the reason that the resistance of the magnet helices virtually
becomes a portion of the internal resistance of the generator, and when the internal
resistance of the generator circuit is thus increased, the generator itself is not self
regulating, and it is not possible to ring satisfactorily or to receive calls from other
stations.
•
Having therefore, ringer magnets of high resistance and self induction I connect
No
them at the several stations in a permanent bridge of the main line.
other appliance is included in this permanent bridge or cross wire; and the
automatic telephone switch has no control over the said bell branch which is
unadjustable.
The outgoing signals are transmitted by a magneto generator as usual. This
is included in a second bridge or cross wire which however is normally open, and-

page_text: which is closed only while the station is in the act of transmitting a call. It is
brought into action by operating a circuit closer which may be a manually operated
key, or an automatically operated circuit closer.
When the generator bridge is closed in this way it forms a second bridge or
cross connection between the main wires in parallel circuit with the permanently
closed bridge circuit of its own ringer, and with the bridge circuits of the ringers
at all the other stations.
The telephonic instruments are placed also in a normally open cross wire or
bridge between the two sides of the line. This is controlled by the automatic
telephone supporting switch. When the receiver is in place the telephonic bridge
circuit is open or broken at the upper contacts of said switch; but when the
receiver is removed from its support, the switch closes the telephone bridge
circuit.
It will thus be seen that each station comprises a normally and permanently
closed bridge including the ringer magnets and two normally open bridges including
respectively the call sending generator and the telephones, and each adapted when
closed for use to form an additional bridge in the same station parallel to the
ringer bridge.
Sometimes the construction of the apparatus, is varied so as to cut the ringer
magnets out of the circuit when the generator of the same station is operated,
instead of placing them in a permanently closed bridge circuit. The loss of that
part of the generator current which would be shunted through the ringer of the
calling station is thus avoided. As it is desirable, however, to have a test to shew
whether the line is in order or not, the ringer magnets are wound with two coils,
one of fine wire, to a high resistance, and the other a low resistance coil, which
remains in the direct circuit when the generator is operated, while the high
resistance coil is shunted out. Or a separate ringer of low resistance is placed in
the generator circuit, instead of making the first mentioned ringer magnets double
wound.
On this plan the ringers on the several stations remain bridged across the
circuit, for receiving the signal, only the high resistance coils of the ringer of the
calling station or the high resistance ringer when two are employed being dis-
connected.
Or, the signalling apparatus at each station may be placed in a derived circuit
to earth, all these derived circuits being taken from one side of the metallic circuit,
when a double line is used. By attaching a part of these derived circuits however
to one side of the metallic circuit, and the rest to the other side, with a hand or
other switch for transferring the signalling apparatus of any given station from its
own side of the circuit to the other side, a system is arrived at which allows me to
connect a large number of stations together, while reducing by one half the
amount of ringing heard at each station but intended to call the attention of other
stations.
The principle of working, remains practically the same, namely, that the calling
shall be done by means of high resistance ringer magnets, connected in bridged or
derived circuits, operated by a generator whose current is divided between all the
ringer magnets left in circuit, while the talking is done with telephones in bridged
or derived circuits, disregarding the slight loss of current through the high
resistance ringer magnets from line to line or to earth.
Dated this 16th day of March 1901

page_text: COMPLETE SPECIFICATION.
Improvements in Signalling and Telephonic Systems.
I, JOHN EDWARD KINGSBURY, of 79 Coleman Street, in the City of London,
Manager, (a communication to me from abroad by the Western Electric Company,
of Chicago, Illinois, United States of America) 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:-
The object of this invention broadly stated, is in a telephone circuit having a
number of stations to arrange the apparatus in parallel circuit or multiple arc,
preferably on a metallic circuit; and to be able from any one station to signal
satisfactorily all of the other stations; and also to enable the telephonic trans-
mission and reproduction of conversation between any desired two of the said
stations, to be successfully effected.
To this end the invention comprises the employment of ringer magnets having a
high co-efficient of self induction; the discontinuance of the ordinary practice of
including the call sending generator and the ringer magnets serially in the same
circuit when calling; the connection of the said appliance in different and parallel
bridge cross wire or derived circuits of the main line; the ringer magnet bridge
being normally and permanently closed or continuous at all stations; and the
generator bridge circuit being normally open or discontinuous but adapted to be
closed while sending a call; and the connection of the telephone in a third bridge
circuit at each station this also being open when the telephone is not actually in
use, but closed in multiple arc with its own ringer magnet and of course with the
ringer magnets of other stations, when in use.
By adopting these improvements, and combining them as shewn in the drawings
and described as herein I am enabled to provide signalling and telephonic systems
which are self regulating.
In the drawings
Figure 1 is a diagram of a telephone circuit having a number of stations and
embodying the invention.
Figure 2 is a diagram of a station apparatus and its electrical connections
complete; and
Figure 3 is an elevation of the ringer magnets preferred indicating the actual
size of the same and showing thereby one mode of raising its self induction.
In Figure 1 the telephone circuit as a whole is represented by the letter L and
At station 9 the
its two line wires respectively are designated as 1 and 12.
apparatus and electrical connections are indicated and in Figure 2 the same
connections are more completely illustrated. It will be seen that at each station
the apparatus is connected with the two wires of the main line a wire 13 extending
inward from line wire 1 and a wire 14 from line wire 1. Should any telephone
station be nearer to one of these loops than it is to the main line, a second loop may
be connected with the two wires of the first as shewn at station 5 and 6 where a
branch 13 extends from junction with the wire 13 to station 6 returning by
wire 14 to a junction with wire 14.
As shown at station 9, B indicates the ringer magnets included permanently in a
bridge or cross wire extending across the loop between station wires 13 and 14;
although if the line employed were single instead of double the said magnets would
When the call bells are
be included in a permanently closed earth branch.
connected at a number of stations on one circuit in multiple arc, it is of course
required that call signals transmitted from one station shall ring the bells at all the
other stations, that having signalled and attracted the attention of any given
station conversation may be readily exchanged and that the loudness of the
reproduced speech shall not be impaired or perceptibly diminished by the
and 1 involved by
permanent connections between the two main wires

page_text: the presence of the ringer magnets connected as described at the unemployed
stations.
This can best be accomplished by providing call bell electro magnets which
have a high co-efficient of self induction. To construct ringer magnets fulfilling
this requirement the iron cores which are yoked together by an iron heel as usual
are lengthened out and the electromagnet wound with fine wire to a resistance of
about 1000 ohms.
When ringer magnets constructed as above are used, the ordinary mode of
connecting them serially in the same circuit with the generator coils is
impracticable, for the reason that the resistance of the magnet helices virtually
becomes a portion of the internal resistance of the generator, and when the internal
resistance of the generator circuit is thus increased, the generator itself is not self
regulating, and it is not possible to ring satisfactorily or to receive calls from other
stations.
Having therefore, ringer magnets of high resistance and self induction I connect
them at the several stations in a permanent bridge of the main line; as in the
diagram of station 9 where the bridge leads from the point on wire 13 by the
wires 24 and 25 and through the said ringer magnets B to the point on wire 14.
No other appliance is included in the permanent bridge or cross wire; and the
automatic telephone switch s has no control over the said bell branch which is
unadjustable. No other part goes through the station for the station is normally
closed so that the full force of any ringing current entering the said station if not
itself using the line necessarily traverses the ringer magnet helices and produces
the incoming signal.
The outgoing signals are transmitted by a magneto generator G, as usual. This
is included in a second bridge or cross wire which however is normally open, and
which is closed only while the station is in the act of transmitting a call. It is
brought into action by operating the circuit closer which as shewn is a
manually operated key, but which may of course be an automatically operated
circuit closer.
When the generator bridge is closed in this way it forms a second bridge or
cross connection between the wires 13 and 14, and hence between the main
wires 1 and 1', in parallel circuit with the permanently closed bridge circuit
of its own ringer, and with the bridge circuits of the ringers at all the other
stations.
The telephonic instruments are placed also in a normally open cross wire or
bridge between the two sides of the line. This is controlled by the automatic
telephone supporting switch 8. When the receiver is in place the telephonic bridge
circuit is open or broken at the upper contacts of said switch; but when the
receiver is removed from its support, the switch closes the telephone bridge
circuit.
These connections may be more easily comprehended by a study of Figure 2,
which however does not differ in any material point from station 9 of Figure 1 ;
and it will be seen by reference to either that each station comprises a normally
and permanently closed bridge including the bell magnets and two normally open
bridges including respectively the call sending generator and the telephones, and
each adapted when closed for use to form an additional bridge in the same station
parallel to the ringer bridge.
Sometimes the construction of the apparatus is varied so as to cut the ringer
magnets out of the circuit when the generator of the same station is operated,
instead of placing them in a permanently closed bridge circuit. The loss of that
part of the generator current which would be shunted through the ringer of the
calling station is thus avoided. As it is desirable, however, to have a test to shew
whether the line is in order or not, the ringer magnets are wound with two coils,
one of fine wire, to a high resistance, and the other a low resistance coil, which
remains in the direct circuit when the generator is operated, while the high
resistance coil is shunted out. Or, a separate ringer of low resistance is placed in

page_text: the generator circuit, instead of making the nrst mentioned ringer magotis uvuvi
wound.
On this plan the ringers on the several stations remain bridged across the
circuit for receiving the signal, only the high resistance coils of the ringer of the
calling station or the high resistance ringer when two are employed being dis-
connected.
Or, the signalling apparatus at each station may be placed in a derived circuit
to earth, all these derived circuits being taken from one side of the metallic circuit,
when a double line is used. By attaching a part of these derived circuits however
to one side of the metallic circuit, and the rest to the other side, with a hand or
other switch for transferring the signalling apparatus of any given station from its
own side of the circuit to the other side a system is arrived at which allows me to
connect a large number of stations together, while reducing by one half the
amount of ringing heard at each station but intended to call the attention of other
stations.
The variations in the system resulting from having the ringer magnets in
direct generator circuit, to be shunted out by their own generator, are shown in
Figure 4.
The variations resulting from placing the signalling apparatus in a derived earth
circuit are shewn in Figures 5 and 8 while the arrangement of the signalling
apparatus in two sets is shewn in Figures 6 and 7.
The principle of working remains practically the same, namely, that the calling shall
be done by means of high resistance ringer magnets, connected in bridged or derived
circuits, operated by a generator whose current is divided between all the ringer
magnets left in circuit, while the talking is done with telephones in bridged or
derived circuits, disregarding the slight loss of current through the high resistance
ringer magnet from line to line or to earth.
At the
In Figure 4 A is the magneto electric call mechanism. a is the crank handle by
which it is operated. The axis passes through the boss of the wheel a¹ and is
pressed towards the left by a coiled spring contained in the spring box a³.
extremity of the axis is a pin a which when the apparatus is at rest makes contact
upon a spring 6 as is seen to the left of the figure. When the handle is turned
however inclines a' upon the handle and the boss of the wheel a' cause an endwise
motion of the axis before the wheel a' begins to turn with it. This movement
takes the pin a out of contact with the spring as is seen to the right of the
figure. a is a flange on the axis which makes contact upon the spring c when the
axis moves to the right.
A call current from the station on the right of the figure may be traced through
the station on the left as follows:-by line wire d to spring b, thence to the metal
frame of the call mechanism A, onwards by the wire e to the main coils f on the
bell magnet, back by the test or auxiliary windings g of the magnet and so to the
line wire h.
The telephonic currents may be traced from d through the telephone connected
at i, through the secondary of the induction coil at k, through the switch hook /
and by the wire m to h; the switch hook at this time closing this circuit and also
the local or primary microphone circuit.
The outgoing call current may be traced in the instrument to the right of the
figure as follows from the armature of the magneto electric apparatus A to the
insulated pin n at one end of the armature axis thence to the spring b and the line
wire d. In the other direction; from the armature to the metal frame of the
apparatus A, thence by the spring c to the wire o, onwards by the test winding g of
the bell magnet and so to the line wire h.
In Figure 5 the call instruments of six stations are represented; the coils of the
bell magnet in each instrument are connected at one end to earth and at the other
end to one of the line wires, three instruments to one line wire and the remaining
three to the other line wire. The armature coil of the magneto electric generator
in each is connected by one end to earth and by the other end to a switch by which

page_text: it can at pleasure be put to one or the other of the line wires. The call will then
be received at three only of the six stations and which three depends on the
selection made between the two line wires.
In Figure 6 an arrangement suitable for one of the stations in Figure 5 is
shewn. Figure 6 also illustrates the use of a separate test bell. The circuits may
be traced as follows:-the outgoing call current passes from the armature of the
generator G to the insulated pin at the extremity of its axis, to the switch hook
contact at C (which is then closed) thence to the other switch S and by it to one
or other of the line wires, which are connected at L', L³, according to the position
in which the switch is placed. The return is from earth through the test bell B,
the key K which is depressed, to the frame of the generator and so back to the
armature coil.
The incoming call current passes from one or other of the line wires, by the
switch S to the contact at C, thence through the main bell M to earth.
The telephonic current may be traced from line 1 by switch S, switch hook H,
the secondary of the induction coil I, the telephone T to the line wire 12. The
primary or microphone circuit is arranged as is usual.
In Figure 81 and 1' are the line wires; 1, 2, 3 and 4 are the stations on the
line. The stations are connected to the respective lines by branches to the outer
terminals as shewn. The centre terminal is connected to earth. The circuits of
the instruments at the stations 1, 2, 3, 4 in Figure 8 are shewn in detail in Figure 7
where the ringer circuit may be traced from the point a to the centre terminal and
thence to earth.
Having now particularly described and ascertained the nature of my said inven-
tion and in what manner the same is to be performed I declare that what I
claim is :-
1. In a signalling and telephonic system the combination of ringer magnets of
high resistance and high co-efficient of self induction bridging across the two main
line wires of a telephone circuit or across a single wire and earth at each station
a generator of electricity for sending calls at each station also bridging across the
line wires when in action and a telephone instrument also in a bridged or derived
circuit when being used so that when talking the slight loss of current through the
high resistance ringer magnets is neglected.
2. In a signalling and telephonic system the combination of a call-bell magnet of
relatively high resistance at each station included in a branch circuit uniting the
two sides of the telephone circuit, or from one side to earth, and a generator of
electricity for sending calls at each station, adapted when operated to be connected
between the two sides of the telephone circuit, or between one side and the earth,
in multiple are with the call-bell magnet, substantially as described.
3. A telephone circuit having two or more stations upon it, ringer magnets of
high resistance and high co-efficient of self induction permanently bridged across the
line at each station.
Dated this 16th day of Danamba 1201