US813560A - Telephone system for central stations. - Google Patents

Description

EATENTED FEB. 27, 1906.

IONS.

APPLICATION FILED APR. 16,1902.

UNITED STATES PATENT OFFICE.

GUSTAF LAMBERT, OF CHARLOTTENBURG, GERMANY.

TELEPHONE SYSTEM FOR CENTRAL STATIONS.

Specification of Letters Patent.

Patented Feb. 27, 1906.

Application filed April 16, 1902- Serial No. 103.123.

specification.

It is well known that in the installation of telephone central stations of larger size it has frequently been found convenient to arrange the subscriber-circuits in the central station in two or more groups for the pur ose of both saving in multiple jacks and cab es and also in order to obtain a high efiiciency of the central station. The subscribers are for this purpose provided with a signal-lamp, and the terminalsof the subscriber-stations are provided with a suitable key for calling u i the difl'erent groups of the telephone centra station. In cities with two or more telephone central stations of larger extent, where the majority of conversations are held on the in-' tercomnnmication lines and only so many subscriber-circuits need to be arranged in the central station as are contained on a milltiple circuit, it is, however, convenient to arrange the subscriber connections in a group and to arrange the leading-off intercommunication connections in one or several separate groups, each subscriber being provided with signaling devices, the number of these signaling devices corresponding to the number of the other stations on the same system. Thus the signal of the subscriber indicates directly with what station he desires to be connected.

"The operator therefore does not need-to inquire; but it is only necessary to establish communication with the desired central station of an intercommunication circuit which is not-busy; In consequence of the smaller number of talking-circuits within the central station in this case a larger number of subscriber-circuitsmay be arranged in the first group upon each operating-tablethan was ordinarily the case. In the other groups intended for the leading off intercommunication lines up to thousand circuits may be attended to by the operator.

This invention has reference partly to the last-mentioned arrangement of the lines in separate groups for subscribers and for intercommunication lines, and it refers partly to a switching device particularly suitable for this purpose and for the first-mentioned arrangement in groups of subscribers in general.

The system and device is shown on the accompanying drawings for a number of four groups.

The subscriber-table a is provided with the speaking-key I), included on the branch 0 of t 1e subscriber double circuit 0 d, the arrangement being such that by depressing the key b the branch 0 of the subscriber circuit is grounded. By this earth connection the circuit of the battery 0 is closed through the electromagnet f, the armature g of the electromagnet h, contact-piece 2, the conductor 0, and the key I). The alarm apparatus of the subscriber-table may be arranged in series with a condenser, or it is provided with so large a resistance that the current of the battery '6 does not actuate the electromagnets f and 19, respectively, included upon the conductors c and (1 while the telephone is suspended from the hook 0' and the key I) re mains inoperative. Upon depressing the key I; the electromagnet 7 will attract the armature i, pivoted upon the stationary pin 11. The hook 7a, which is attached to the armature t and is rotatable upon the shaft 12, re, volves the wheel 1 and turns the arm m, con' nected therewith, so as to cause the latter to rest against the contact a, the holding-dog 4 preventing backward movement of Z. If the speaking subscriber desires to obtain a connection within the group I, he allows the key I) to reassume its original position of rest, and he then takes his telephone off from the hook 0. the double circuit 0 d are connected with each other .by the medium of the subscribertable. This results in a series connection of the coils 8 9 of the electromagnct p, which is shown in full lines, with the electromagnet f and upon the circuit of the battery 6, a cir cuit being established from one terminal at the battery e through the armature t, the armature g, contact-piece z, .conductor 0, subscribers table, conductor d, the contact 5, the armature 3, and the coils S 9, t0 the other terminal of the battery e. Inasmuch as the electr'omagnet 1) has a very considerable number of convolutions with comparatively high resistance, while the electromagnet f has a small number of convolutions with low resistance, the current thus "produced will be sufficient only to excite the first electromagnet 3 but it will refuse to excite the latter elec- By this means the two branches of tromagnet. The armature g is attracted, it closes the contact 13, and thereby establishes ,a local circuit from one terminal of the battery 0 through r, the contact 5, and the armature t, the dotted con'volutions (6-7) of the electromagnet p, the armature g, the contact 13, the glow-lamp a in the group 1, contact n, arm m, and wheel l to the other ter minal of the battery. Simultaneously with the contact 13 the contact 2 is closed, and the electromagnet f is shortcircuited by means of the circuit-closing piece Z, which is con nected to the armature g and is insulated therefrom. The local circuit which actuates the armature g and the signal-lamp u remains closcdfor a sufiicient length of time until the operator of the group I answers to the call by inserting the plug 12 into the jack w, even if the hook 0 should be depressed in-the meantime.

B inserting the plug 1) into the jack w the con uctor 9cis grounded, thereby closing the circuit of the battery e by way of the electromagnets h and 1 arranged in shunt-circuit. The exciting of the electromagnet h results in the interruption of the contacts 8 and 2, thereby cutting out in the first place one of the branches 0 of the two branches 0 d of the double conductor of the speaking subscriber from the switching device, besides the coils 6 7 with the lamp a are cut off from the battery c. When the electromagnet y is excited, the contact 5 is broken in the first place, thus cutting off the coils 8 9 of the electromagnet p from the branch (1. Then the extension 0 the armature 3 pulls the dogs is and 4 away from the wheel I, thus releasing the latter and causing the armm to return to its initial position by the action of its own weight. The short circuit with the electromagnet 7 established by the contacts 1 and 2 is for the purpose of preventing any further displacement of the arm 'm by pressure upon the key I) after the telephone has been taken off the hook or in consequence of the connection to earth which might be established upon the insertion of the plug into the jack w. If the speaking subscriber wishes to actuate another of the signal-lamps which belong to his line in another group, it is only necessary to depress the key I) so many times as the number of the desired group indicates.

What I claim, and desire to secure by Letters Patent of the United'States, is-

1. A telephone system comprisin two or more groups at the central station W ich the subscriber may call up directly and whenever desired, a loop-conductor connected to the telephone central station, one branch of the double conductor-line of the subscriber including an electromagnet f at the station, a circuit-closing piecemactuated b said elec-. tromagnet, so as to assume the cal ing or signaling position, another electromagnet pupon the other branch adapted to be put in connection with the said circuit closing piece m, and a signal lamp u the circuit of which is maintained closed b means of the connections between said e ectromagnet p and said circuit-closing piece until the call is answered from the station, the said signal-lamp being arranged in the answering group.

2. A telephone systemcom rising a loopconductor line connected to t e central station, an electromagnet p in one branch of said loop and an electromagnetf on the other branch, a selective means actuated by said electromagnet f and means to short-circuit the electromagnet f by the actuation of the electromagnet p until tfie'call is answered.

3. In a telephone system, com rising a loop-conductor liueconnected to t e central station, substantially as described, and an electromagnet f on one branch and an electromagnet p, a signal-lamp on the other branch in connection with said electromagnet 0, an inquirylug c and two electromagnets h and g excite by inserting the said plug, the armature of the electromagnet 7 cutting out the subscriber-circuit. of the electromagnetsfand p from the signa' -lamp, while the armature of the electromagnet'y causes the circuit-closing piece m to return to its initial position and disconnecting the electromagnet p from the subscriber-circuit.

4. Telephone system including magnets p, f and circuit connections, substantially as described, in which the number of cbnvolutions and the resistances of the electromagnetsf and p are so calculated that the circuit generated in the subscriber-table after taking the telephone off its hook, actuates the electro ma net p only, but not the electroma et f, an selective means operated by said e 'ectromagnets.

In witness whereof I have hereunto s' ed my name in the presence of two subscri ing witnesses.

GUSTAF LAMBERT. Witnesses: I, WOLDEMAR HAURT,

HENRY HASPER.

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