Year: 1893

page_text: Date of Application, 27th Sept., 1893-Accepted, 22nd Sept., 1894
We, OSWALD FRANZ, of Zossenerstrasse 33, and GUSTAV OTTO, of Oranien-
strasse 187, S.O. both of Berlin, in the Empire of Germany, 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 present invention relates to improvements in multiple switch-boards for
telephonic exchanges having the object, as in the case of other multiple switch-
boards, of enabling the operator to connect the line of any subscriber with any
other, on that or on any neighbouring line connected with a multiple switch-
board.
In the accompanying drawings the parts of the switch-board are represented.
Figure 1 shows a relay in front elevation and
Figure 2 in plan,
.
Figure 24 in side elevation ;
Figure 3 represents a connecting cord with a ring-switch, the latter consisting
principally of two rings insulated from each other,
Figure 4 a key,
Figure 5 is a diagram, showing the circuits.
The switch-board contains the following parts:
A. One relay for each subscriber, consisting of two electro-magnets opposite
each other, between which the armature is delicately supported by two pointed
screws for the purpose of touching alternately the contact-pieces c², c², or c³, ct.
This armature consists of a piece of soft iron i, placed between the cores of the
two electro-magnets. This soft iron is closely surrounded by a plate b made of
india rubber or other similar material. This plate b is at the same time the
connecting link between the bars and ³, which are made of good conducting
material such for example as brass and provided with holes for receiving the
pointed screws 1 and 9. The upper parts of these bars are made thicker and are
arranged in such a manner as to oscillate in two directions r¹ and making contact
simultaneously with the two bars c' and c³ respectively, on the side of the electro-
magnet m, or with the contact-pieces c and c³ respectively on the side of the
electro-magnet m¹. All the beforementioned parts are fastened to the base plate g,
of slate or any other insulating material.
B. The connecting cord h provided with a ring-switch consisting essentially of
two rings ³,, insulated from each other and held apart by spiral springs s.
One ring is electrically connected with the relay and the other with the
battery b¹; one ring may be pressed upon the other by means of a non-conducting
bulging part or cushion o fastened to the connecting cord. This cushion is pressed
by a weight w fastened to a roller q, on to the upper ring so as to make contact
between the two rings as soon as the plug p of the connecting cord is put into the
opening of the contact-piece e¹ of the earth wire, this contact-piece opening is
placed as close to the ring switch as will permit the part of the connecting cord,
situated between the cushion o and the plug p, to remain without tension, in such a
manner, that the weight w draws the upper ring r down on to the lower one ›³.
In this way a connection is formed between the battery and the relay.
As soon as the plug p is put into any of the plug contacts replacing the spring-
jacks, the beforementioned part of the cord must be stretched so as to lift the
cushion fastened to the cord, and to set free the upper ring r, breaking the contact
with the lower one, the upper ring being raised by the springs s. The 'plug p of
DQ77

page_text: the connecting cord is made in such a manner that only its lower part is conducting.
The diameter of its lower conducting part is equal to the inside diameter of the
lower ring p² of the plug contact, whereby the plug, if put into the plug contact
has no electrical connection with the upper ring p¹ of the plug contact.
C. The key and the annunciator drop are of the ordinary construction.
D. The plug-contacts used instead of the spring jacks, consist each of a
conducting ring p', over which another conducting ring pl is placed, the same being
separated by an insulating part of the switch-board, the upper ring serving as a
switch, preferably for altering the position of the armature of the called-up
subscriber. The object of these plug contacts will be described hereafter.
Of all the parts described in A to C, the following are necessary for each
.separate subscriber's line: 1 relay, 1 connecting cord with its accessories, and
1 main key with 2 auxiliary keys for the purpose mentioned hereafter.
The plug-contacts described under D are repeated for each subscriber at each
operator's place, being within the reach of the operator at the multiple switch-
board for telephonic exchange.
Supposing there are 10,000 subscribers, about 23 operators' places will be
wanted that is 10,000 plug-contacts for each place will be necessary and as many
switches (cut-outs) destined to switch (cut-out) the contact line.
According to our invention the parts in A to C are only wanted 10,000 times
divided by 23. Each plug-contact and each annunciator drop carries the number
of the corresponding subscriber. All plug-contacts belonging to one number are
connected by a wire, described as a plug contact wire. The plug switches also
are connected with each other by wire (cut-out).
The switching of the apparatus in general will be clearly seen. Assuming
that the apparatus has only two subscribers, because any complicated apparatus
is only a multiplication of the apparatus now to be described. The apparatus is
arranged in an easily accessible way, being placed on a table in such a manner
that two operators may work at it at the same time, in this case only half the
number of the plug contacts will be necessary for each operator's place, because
the plugs of all the connecting cords being at one operator's place, they may be
put into any of the plug contacts, which are in rows between two operators'
places, placed one opposite the other.
The inain line of the subscriber XXX leads from one terminal point directly
to the earth, the same forming as usual the return part of the circuit, and the
other part going through the connecting line *** which leads from the subscriber
to the central office that is to the pointed screw 1 of the relay, the latter being
now in its second position (see Figure 5; XXX) and from there to the armature
bar and the contact-piece c' and terminal 2 and to terminal 3 of the coil of the
electro-magnet m, and thence to the above mentioned wire ***, connecting the
plug contacts of the subscriber XXX.
The terminal 4 of the electro-magnet m is connected with the terminal 5 of
the contact-piece c³, and likewise the terminal 6 of the electro-magnet m' is
connected with the terminal 7 of the bar c. The screw 8 is electrically connected
with the plug switches of the subscriber XXX and the screw 9 is connected with
the lower ring 3 of the ring switch, enclosing the connecting cord, as mentioned
above. The terminal 10 is connected with the terminal 11 of the auxiliary key k
the terminal 11° of which is connected with the electro-magnet of the annunciator
drop d and beyond it to the contact of rest 12 of the auxiliary key k".
The contact terminal 13 of the last key is electrically connected with the contact
of rest 14 of the main key k, the other contact 15 of the main key is connected on
one side with one terminal of the battery *** and on the other side with the upper
ring of the spring switch. Besides which there is an electrical connection
between the terminal 16 of the auxiliary key k" and the terminal 17 of the auxiliary
switch, the operator's telephone T and the earth.
The above mentioned switching is repeated in all subscribers' lines leading to the
multiple switch-board.

page_text: The way in which the apparatus is worked will now be described, and the way
the switch-board is used will be seen. If I desires to speak, say to XXX, he
presses the knob of his telephone, whereby his local battery is connected with the
multiple switch-board, the relay being in the normal position (see Figure 5; I)
and the earth effecting the return, that is to say the current of the above mentioned
circuit flows from the main line to the pointed screw 1 bar r³, contact-piece c³,
screw 10, screw 11 of the auxiliary key k', through the contact of rest of the
same 11 to the electro-magnet of the annunciator drop d', which latter falls down
informing the operator at the central office that the subscriber desires to be
connected.
From the annunciator drop the current goes to the contact of rest 12 of the
other auxiliary key k¹ and over the lever of the auxiliary key and the
terminal 13 to the upper contact 14 of the main key k, and from there over
the lever and bottom contact of the main key k, the connecting cord h, through the
plug contact e¹ to earth, the latter forming the return. Afterwards the operator at
the central office presses the knob E of the auxiliary key k', whereby bringing the
lever in contact with the terminal 17 and connecting his telephone T to the circuit-
line of the subscriber I, the earth forming now the return. By this procedure the
operator is enabled to receive the order of the subscriber desiring connection say
with XXX.
Before making this connection the operator ascertains whether the line is free or
or not by pressing the knob A-of the key and by putting the plug p of the
connecting cord into the plug contact of the line of the subscriber XXX, whereby
the current of the battery is closed beyond the plug contact-line p'-and the
telephone. As soon as the line is free a cracking noise produced by a passing
current is heard in the telephone, if not, the current does not go through the
operator's telephone and no cracking noise will be noticed.
Supposing the latter to be the case, the operator informs the calling up
subscriber that the line is not free by pressing the knob of the key thus
inserting his telephone into the circuit of the subscriber.
The operation of the relay and of the connecting cord with the ring-contact
belonging to the latter are especially to be mentioned. In one position of the
armature the relay is, as mentioned above, (see Figure 5, I) in repose and ready
for connecting the subscriber with the central office. If the subscriber I is to be
connected with subscriber XXX, the relay-armature (Figure 5, XXX) if it is
inclined towards m', must be switched over into the other position of the armature.
This latter switching over is done automatically as soon as the operator, as
mentioned above, inserts the plug p into tho plug contact p² of the subscriber XXX.
This operation is effected in the following manner. By the connection of the
plug p, belonging to the connecting cord, with the plug contact p³, the circuit of
the battery is made through the coils of the electro-magnet m*** only for a
moment, whereby the electro-magnet is energised and thereby the armature is
attracted and in consequence of this the circuit of the battery is broken.
The conversation being finished, the operator in taking out the plug p touches
with it the contact ring p', whereby the electro-magnet m*** is again inserted
into the circuit of the battery 6, the return going through the earth. Thus
the armature is switched over again to rest, and thus the circuit of the main line
of the subscriber passing the relay and the annunciator drop is closed, the
subscriber being again in normal connection with the central office.
Having now particularly described and ascertained the nature of our said inven-
tion, and in what manner the same is to be performed we declare that what we
claim is:
A switch-board for telephonic communication, in which the main circuit leads
directly to the calling-up apparatus; further in which a relay is inserted in
each circuit, said relay including in addition to the main circuit also a battery-
circuit, a plug-contact circuit and a cut-out circuit; said relay also serving to

page_text: automatically place the main circuit of the person calling up in communication
with the plug-contact circuit of the person called up, on the insertion of the
plug p of a switching-on cord h, all substantially as above set forth.
Dated this 26th day of September 1893.
J. G. LORRAIN,
Associate Agent.