Improvements in Telephone Systems.
Year: 1897

page_text: Date of Application, 15th Dec., 1897--Accepted, 15th Dec., 1898
Improvements in Telephone Systems.
I, GEORGE RITTER, of 12, Hohenstaufenstrasse, of Stuttgart, in the Kingdom of
Wurttemberg, German Empire, Chief-Inspector, do hereby declare the nature of
this invention, and in what manner the sane is to be performed; to be particularly
described and ascertained in and by the following statement:-
This invention relates to improvements in telephone systems differing from
ordinary systems by the property that the operator's telephone is automatically put
in or out of the circuit and that further the clearing-out indicator i.c., the flap
indicating the end of a speech is also put in or out of the subscribers circuits which.
are either connected with the central-office or with each other and finally that the
call signals are automatically effected.
In the telephone systems hitherto in use it has been necessary to operate the
commutator and the electric bells by hand, whereby the same are either so arranged,.
that they must be operated separately or in such manner connected with each other
by means of plugs, that the commutator and the electric, bells are operated
simultaneously.
I
11.
In the system hereinafter described the commutator and electric bells are.
operated by means of electro-magnets switched on an auxiliary circuit formed, by
the use of plugs to establish the communication between subscribers, and excited
by contact.
In Figure 1 of the accompanying drawing two subscriber's lines 11 11, 12 12 are'
shown with earth return; kare spring-commutators with sockets h¹h².
In this figuro 2 plug-pairs S¹ S² (1), S³ S4 (II) are shown with the connections
belonging thereto.
::
Both arrangements I, I are alike, and either the one or the other can be used for,
the present case, the said arrangement of the circuits only varying in the location,
of the battery r, i.c., for the plug-pair S³ S (II), the battery is in au auxiliary,
circuit, whereas for the plag-pairs S₁ S2 (I) the said battery is in the speech
circuit.
.:
'
The object of representing two plug-pairs in Fig. 1 is simply to show the above
indicated varying position or location of the battery.
In the central office is arranged a battery p'one pole of which is connected with
the sockets h¹ h². . . ¸, the other pole being electrically connected with the.
ferrules of the alarm plugs SS by means of the line x-x and the winding of the
electro-magnets m.
1
As shown in the drawing the latter pole of the battery p is also electrically*
connected with the ferrules of the control plugs S. and S³. This connection, when
multiple-switches are used, serves to test whether the lines are free or, engaged.
Besides this an auxiliary winding of the flaps f is arranged between the
sockets h¹h and the battery p, in order to raise said flaps automatically. These,
connections are only indicated in Figure 1 in order to give a complete diagram of
the plant but they do not form any part of the present invention.
With the pairs of switch plugs I and II commutators v v² are connected having,
the purpose of alternately connecting the operator's telephone t or the windings e¹

page_text: of the flaps c indicating the end of a speech with the circuit of the pairs of plugs.
The armatures a¹ a² of the electro-magnets m are connected in such manner with
the levers of these commutators, that when no current is. passing the line, the
operator's telephone t is switched on the speech-circuit.
The communications between two subscribers are effected in the following
manner:
After the falling of the flap the calling subscriber is controlled by putting a
control-plug S¹ or S³ into its spring-commutator, which may be done, as the
operator's telephone is connected with the speech-circuit. The path of the latter
is the following:
From the subscriber's place the circuit flows through the line to the first
spring-contact k¹, which is broken by means of the inserted plug, whereby the
speech-circuit comes from the contact-spring to the plug respectively the speech-
circuit of the same (full lines) and from the latter through the arm of the
commutator to the operator's telephone.
When the subscriber's number is ascertained, the bell-plug belonging to the
control-plug is placed into the respective spring-contact, whereby the auxiliary
circuit of the battery p is closed by the contact of the ferrule with the
socket h².
The electro-magnet m is hereby excited and the armature is attracted and the
winding e¹ of the flap c is switched on the speech-circuit instead of the operator's
tolephone.
If we suppose that the plug S2 of the pair I is placed into the spring-contact k²
opposite to the former, the current will take the following path.
The said current of the battery p passes along the line - and reaches to the
auxiliary line of the pair of plugs I (dotted lines) on which the electro-magnet m is
switched. As the ferrule of the plug S2 is in contact with the socket 2 of the
spring-contact, the current coming from the auxiliary line of the plug S2 can
return over and 2 and the line connecting the sockets h² and the winding w² of
the flap f, to the line 9-9 and from the latter to the battery p.
When the armature a¹ is attracted by the electro-magnet m the arm of the
commutator v comes against the lower contact and a current flows through the
speech-circuit (see the description of the current given above) instead over
the operator's telephone t over the winding e¹ of the clearing out indicator.
During the movement the arm 3 of the commutator (at the commutator v² the
arm 2) slides on a part connected with the auxiliary winding e² of the clearing out
indicator, whereby a branch current of the battery ? passing said auxiliary winding
is closed temporarily by means of the line a-a, the auxiliary line of. the plugs S
and S, the arms 2 and 3 respectively, the commutators v¹ and respectively,
and the lines y-y and q-q. This causes the clearing out indicator c to rise
automatically. The batteries 7 switched at I in the speech circuit and at II in the
shunt of the same, serve to automatically give the call at the central office, because,
as shown in Fig. 1, in the case of the plug-pair S1 S2, the battery is in the plug-
circuit. But in the case of the plug-pair S3 S in a shunt with every plug-pair is
firstly the coil e¹ of the clearing out indicator c which is connected to earth; the
battery can therefore be placed in the earth's circuit.
As however all the plug pairs are connected at one and the same commutator
point or board to the last named circuit namely to the earth circuit, it is clear that
one battery will be sufficient, i.e., will furnish enough current for all circuits
connected at one and the same commutator point or board.
In order that the speech or sound vibrations shall be prevented from passing
over from one plug pair to another, through the earth circuit common to both or in
other words through the common earth circuit, it is necessary to impart to the
coil e¹ of the clearing out indicator great resistance, and high self-induction which
would effectually prevent any passage of the speech current from one of the said
plug pairs to another.

page_text: The electric bells of each subscribers telephone are made 'in such manner, that
they are operated by the current coming from the battery 1, 30 that when the
switch-plugs are inserted the electric bell signal sounds automatically.
At the switch-plugs S1 and S2 the path of the current of the battery will be clear.
At the plugs S3 and St it is as follows:
The current flows from one pole of the battery r through the winding e¹ of the
clearing out indicator to the lower contact of the arm of the commutator 2, and.
from the latter to the speech-circuit of the plug-pair II (full lines), here the current
branches off to the 2 lines 1111 and 12 12 (whereby is supposed that the two plugs.
are inserted) and passes through the said lines to the subscriber's telephones being
connected with them and to earth. From here it returns over the lines b b and d d.
to the zinc-pole of the battery r.
As the current of the battery r flows through the speech-circuit connecting two
subscriber's telephones only a direct current can be used direct. If it is desired to
use an alternating current the arrangement shown in Fig. 2 must be employed.
In this figure the same letters of reference are employed as in Figure 1, but a loop
connection for the subscriber's lines is shown, it is, however, clear that this
arrangement may also be used for lines with return by earth. There is besides
the electro-magnet m¹ another maguet m² switched on the auxiliary circuit of the
battery p, which electro-magnets are alternately connected with the auxiliary
circuit.
Also in this Figure 2 only one plug shown as only one location of the battery
is practical in the arrangement of the circuit according to Figure 2, in contra-
distinction to Figure 1 where the varying position of the battery renders the
representation of two plug pairs necessary or desirable, as herein before indicated.
The electro-magnets have a common armature a¹, i.e. the latter is so arranged,
that it is alternately attracted by these electro-magnets. On the pole of the
electro magnet m¹ being directed against the armature a¹ is arranged a metal-
case d, having a shape similar to those employed in connection with aneroid-
barometers. This case is compressed when al is attracted by m¹ and the air
contained in it partly escapes through a valve attached to the case, the return of
the air into the case is, however, made more difficult, so that the case slowly
assumes its original shape. Three levers of the commutator being coupled with
each other are connected with the case d in such manner, that they are compelled
to follow the movement of said case.
In the same manner as shown in Figure 1, the auxiliary circuit is closed by
closing the plug S2, whereby the current of the battery p flows through the
line xx, the winding of the electro-magnet m¹, the lever of the commutator ¹,
the line xx, the ferrule z of the switch plug S2, the socket h (the plug being
inserted) and from the latter through the auxiliary line connecting the sockets and
the line qq back to the battery p, whereby in consequence of the attraction of the
armature by the magnet, the case d is compressed, hereby effecting the move-
ment of the arm 3 and the arms 2 and 1 of the commutator, said arms 2 and 1
being coupled to the first mentioned arın 3, so that the said arms 1 & 2 of the
cominutator w come to lie against the three under contact-pieces (see Figure 2).
The following results :
The arms 2 and 3 break the contact of the two branches of speech-circuit on
that part where the two control-plugs are inserted and connect the part into which
the bell-plugs are placed with the source of current for the electric bell. This
source of current may be a direct or an alternating current motor. The contact is
broken until the case dis again filled with air and the arms 2 and 3 are lifted.
The current for the bell flows as follows:
From one pole of the source of current through the lever 2 of the commutator w
into the line n n from the lattor over the plug-point by means of one spring of
the spring-contact k to one branch of the subscriber's line, back over the bell of
the subscriber's telephone to the second branch of the subscriber's line, over the

page_text: second spring of the spring-contact into the ferrule g of the plug S2 and from
the latter over line o-o and lever 3 of the commutator back to the other pole of
the source of current.
Before the armature has finished its stroke against ml, the bow b connected with
it places the armature a² of the electro-magnet m² against the latter and the
commutator u¹ connected with it is moved from the upper against the lower contact-
piece, whereby the current of the battery p no longer flows through the winding
of the electro-magnet m¹ but through that of the electro-magnet in², whereby the
following is attained:
The armature a² and at the same time the commutator u¹ is kept in its changed
position, the armature a¹ being only loosely connected with the case d, is attracted
by the electro-magnet m², whereby the bow b causes the commutator v to be
removed from its lower contact-pieces and comes to lie against the upper contacts.
This effects the cutting out of the operator's telephone t and the connecting of the
winding e of the clearing out indicator with the speech-circuit. The valve of the
case as well as the springs of the armatures a¹ and are not shown in
the drawing. The connection between two subscribers takes place in the same
manner as above set forth, with reference to Fig. 1.
If it is desired to obviate the resistance of the electro-magnets m of the control
circuits the closing of the auxiliary current may be effected by means of a circuit-
closer arranged in the seat of the bell-plug, which circuit-closer makes contact
on taking off the plug S². For the purpose of controlling the lines, the bell-
plug S2 is provided with a control-button i and a control-line connected with
the operator's telephone (Figure 3). 2 & 1 represent the lower contact rings
of the plugs S S³, said contact rings effecting a connection with the spring-
contacts f&f, upon the insertion of the plugs.
The lines for the subscribers are constructed of double-wire, on taking the'
plug S off, the auxiliary circuit is closed and the current of the battery p flows
over x-x, m, u, y-y, whereby the armature a of the electro-magnet m is
attracted and whereby the operator's telephone is cut out and the winding e--e¹ of
the clearing out indicator is switched in.
The arm of the commutator v slides over the contact piece arranged below it
and closes temporarily the current of p also over the winding of the clearing
out indicator e, whereby the same is raised. The switching on of the battery ris
attained by the plugs S3 S4 (Figure 1), i.e. a comuion source of current for the
alarm circuit can be arranged for the central office, whereby it is necessary, that the
windings ee have a high resistance and high self-induction; because they are
situated in the bridge between the speech-lines.
The continued connection of the operator's telephone t with the lines of the
connecting-plugs during the time of repose shows some drawbacks which
specially appear when double-wires are used and a plug makes short
circuit.
For the purpose of obviating these drawbacks I have arranged in the line which
connects the telephone to the plug-lines, namely upon or at the seat of the plug S¹,
a 'contact breaker d in such a manner that when the said connecting plug Si
rests upon its said seat, the spring 4 of the said contact breaker must be forced
away from the spring 5, by reason or in consequence of the weight of the said
plug S¹, so that now at d¹ a break of the telephone current must take
place.
When however the plug S¹ is again used to effect a connection, it is clear that
the lifting of the said plug from its said seat will cause the release of the spring 4
of the contact breaker din consequence of which the said spring 4 must now
como against the before mentioned spring 5, whereby as is apparent the circuit 'of
the telephone will be closed.
Having now particularly described and ascertained the nature of my said inven-

page_text: tion, and in what manner the same is to be performed, I declare that what I
claim is:
--
1. In commutators for telephone-systems, the arrangement of an auxiliary circuit
having one battery and one electro-magnet and connected on the one side with the
sockets for the spring-contacts and on the other side with the plugs, in such
manner, that upon the insertion of the plug or contact maker into the sockets the
before said auxiliary current is closed, by means of the armature a of the
electro-magnet m connected with a commutator v, a contact or connection is
established between the signal flap belonging to the before mentioned plug or
contact maker and the speech circuit respectively the separation of tho operator's
telephone from the first and also the raising of the signal flap is effected,
substantially as described.
2. A modification of the arrangement characterised in Claim 1, in which the
auxiliary circuit is connected with a contact-piece, being arranged at the seat of the
plug, in such manner, that the auxiliary circuit becomes closed on taking the plug
off, substantially as described.
3. In the arrangement characterised in Claims 1 and 2, the connection of a source
of current with the speech-line of the plug-pairs in such manner, that the current
of the battery and flowing through the lines - of two subscribers connected
with each other is closed and hereby causes the called subscriber's bell to ring
until it is cut out of the speech-line by unhooking the telephone, substantially as
described.
4. A modification of the arrangement characterised in Claim 1, consisting in the
arrangement of a second electro-magnet and a commutator of the auxiliary
circuit in such manner, that the common armature a¹ of the electro-maguets m¹ m²
during its attraction by the electro-magnet m³ connects the bell battery with the
speech circuit, whereby the raising of the clearing out indicator and by reversion of
the commutator u¹ the insertion of the second electro-magnet m² instead of the
electro-magnet m¹ into the auxiliary circuit is effected, whereby the armature a¹ is
attracted by the electro-magnet m² and the alternative connection of the operator's
telephone respectively of the clearing out indicator with the speech circuit is effected
the electro-magnet being provided with a device, retarding the cutting out of the
source of current for the bell independently of the return of the armature a¹ and
interrupting the current which raises the clearing out indicator, substantially as
described.
5. A modification of the arrangement characterised in Claim 1, in which the
lines connecting the operator's telephone with the plug-lines are connected with a
make-and-break contact arranged at the seat of the control-plug in such manner,
that in the state of repose of the same an interruption takes place, but when the
plug is taken off the connecting line of the operator's telephone is in contact with
the plug-line, substantially as described.
Dated this 15th dow of December 1907
J. P. BAYLY,
18, Fulham Place, London, W., Agent for the Applicant.