US679805A - Test system for multiple switchboards. - Google Patents

Description

Patented Aug. 6, I90l. H. G. WEBSTER. TEST SYSTEM FOR MULTIPLE SWITCHBOARDS.

(Application filed Oct. 29, 1900.)

(No Model.)

. 171-0612 for:

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m: NONRIS mus UNITED" STATES PATENT OFFICE.

HARRY G. WEBSTER, OF CHICAGO, ILLINOIS, ASSIGNOR TO THE STROMBERG- CARLSON TELEPHONE MANUFACTURING COMPANY, OF SAME PLACE.

TEST SYSTEM FOR MULTIPLE SWITCHBOARDS.

SPECIFICATION forming part Of Letters Patent N0. 679,805, dated August 6, 1901. Application filed October 29, 1900. Serial No. 34,771. (No model.)

To all whom it may concern.-

Be it known that I, HARRY G. WEBSTER, a

' citizen of the United States, residing at Ohification.

My invention relates to a testing system for multiple switchboards, and its object is the provision of a system for giving an audible signal to the operator when the line called for is in use by diversion of a portion of the current of the main battery without the use of an auxiliary testing-circuit and battery. By means of my invention for making the test I am able to avoid complication of the circuits of the board and at the same time provide a reliable and effective test.

In carrying out my invention I provide means for diverting a portion of the current of the main battery for the purpose of testing and at the same time avoid the diversion of so large anamount of current that it will interfere with the operation of the system.

In this system the plug-tips are when insorted in the jacks all connected to one side of the battery, while the sleeves of the plugs are connected through the instruments included in circuit with the other side of the battery. When the answering-plug is inserted in the jack of the subscriber called and the listening-key is operated, the operators telephone is bridged across the line.

In my invention Iarrange a circuit in shunt of the bridge, including the operators telephone, which is adapted to be closed by the answering-plug when a line called for is,en-.

gaged at another board, and I provide in this shunt test-circuit resistance sufficient to allow a fraction of the current to fiow enough to give the indicating-signal in the operators telephone. 1

My invention I have illustrated in the accompanying drawing, and I will describe it in detail with reference to this drawing.

Two substationsA and B are each equipped with the telephonic appliances and the signalbells usual in common battery systems and each connected through line-wires a a b b, respectively, with spring-jacks c c d d upon different sections of the multiple switchboard at the exchange. The answeringq'acks e (2' may be considered as appearing upon the sections with the spring jacks c d. The double plugs ff are shown with their cordcircuits and the instruments included therein.

In addition there is shown inserted in the spring-jack (1 one plug of a pair at another section to illustrate the condition of the circuits when a line is in use.

I have illustrated diagrammatically the operators telephone g and the generator h with the respective listening and ringing keys g h all included in the cord-circuit. Connected also with one side of the cord-circuit is the clearing-out drop 70, which is also connected with the positive side of the battery Z. Ihave shown also the clearing-out drop with its connection to the cord-circuit of the second section. The clearing-out indicator 7a, which may be assumed to be at the board where the plug sis located, is included in circuit with the subscribers telephone-line, and the continuity of the circuit through the clearing-out drop is controlled by the gravity switch-hook at the subscribers station, so that when the gravity switch-hook is relieved of the influence of the telephone-receiver the clearing-out indicator is placed in one condition of use, and when restored to its normal position by the receiver when it is replaced the clearing-out indicator is placed in another condition of use. I have not shown the complete cord-circuit of the second section, as this is unnecessary, the cord-circuits being identical at the different sections, and I have left out all unnecessary details, illustrating only, and that in a diagrammatic way, the essential features of my present invention.

Connected to the primary of the inductioncoil of the operators telephone at a point between its extremities or to another coil inductively associated with the secondary of the induction-coil is the circuit m, which is adapted to be connected to one side of the cord-circuit by the operation of the operators listening-key. By this means there is connected in the'shunt-circuit around the battery the coil n, which is preferably a portion of the primary and is connected with the negative side of the battery at 0 and completes its circuit through the contactp and the operators listening-key g, the tip of the plug f, the thimble q of the spring-jack d, the sleeve of the plugs, the clearing-out drop is, and the positive side of the battery, thus giving an audible signal to the operator when the circuit Wanted is in use at another board.

The resistance of this test-circuit is low and so related to the branch including the operators telephone that a sufficient current will flow over the test-circuit to give the desired signal.

To indicate the method followed in the op eration of my system, I will describe the operation as it is practiced in an exchange embodying this system of testing.

When the subscriber at one of the stations, as A, lifts his telephone from the hook, the circuit is completed through the lines to the central office through the battery I and through the subscribers drop 0", thus throwing the annunciator and indicating to the operator the fact that a subscriber has called for a connection. The operator inserts one plug of a pair in the answering-jack and with the tip of the other plug touches the thimble in front of the spring-jack of the subscriber called for, as d. This thimble is in a normally open circuit connected ,to similar thimbles associated with the spring-jacks of the same subscriber upon all the other boards. If the line is not in use, this test-circuit including the thimbles being open, no signal will be given to the operator. The plug will then be inserted into the spring-jack and the signal given to the subscriber called by means of the ringing-key h. If, however, as indicated in the drawing, the subscriber called for shall be connected with another subscriber at a difierent board, the test-circuit including the thimbles will be connected with the sleeve of the plug and through the sleeve to the positive side of the battery. Then upon touching the tip of the plug to the thimble the circuit will be completed from the positive side of the battery through the clearing-out drop it, the thimbles, the tip of the plug f, and, the operators listening-key being depressed, the circuit m, including the coil 91, to the negative side of the battery. The resistance in this circuit is low enough so that some current will flow through coil n sufiicient to give a positive signal to the operator, showing that the line called for is busy.

It will be seen that with my invention it is not necessary to use the lines running to the subscribers stations to complete the testingcircuit, and no auxiliary battery or testingcircuit is required. It will be further apparent that I have provided a test system wherein the operator while testing may at the same time listen to the calling subscriber, this re sult being accomplished by reason of the fact that the entire primary of the operators transmitter is not included in a local circuit, but a special primary-coil portion that is preferably a part of the operators complete primary coil that is employed for talking purposes, this special primary-coil portion being in inductive relation with the secondary of the operators outfit.

While I have shown my system of testing as applied to the special form of multipleswitchboard system illustrated and described herein, it will be apparent to those skilled in the art that modifications in the system may be made and my invention still be employed. I do not wish, therefore, to limit myself in my application to the precise system shown and described nor to the exact details set forth herein; but,

Having thus described an embodiment of my invention, what I claim as new, and desire to secure by Letters Patent, is

1. In a multiple-switchboard telephone-exchange system, the combination with a plurality of telephone-lines extending from subscribers stations to an exchange, each telephone-line being connected at the exchange with jacks upon a number of sections of a multiple switchboard, cord-connecting apparatus for uniting subscribers for conversation including a testing-plug, connected thimbles for the jacks of each line, the said test-plugs being provided with tip and sleeve portions, the sleeve portions being adapted for connection with the test-thimbles when inserted, an operators telephone appliance, a listeningkey for connecting same with and disconnecting it from the cord-circuit, a coil portion n in inductive relation with the second ary of the operators telephone appliance, a battery connected between one terminal of the said coil portion and the sleeve-strand, the remaining terminal of the coil portion being adapted for connection with the tip of the testing-plug upon the operation of the listening-key, and a second coil portion also in inductive relation with the secondary coil of the operators telephone appliance adapted for inclusion in a subscribers telephonic circuit, substantially as described.

2. In a multiple-switchboard telephone-ex change system, the combination with a plurality of telephone-lines extending from subscribers stations to an exchange, each telephone-line being connected at the exchange with jacks upon a number of sections of a multiple switchboard, cord-connecting apparatus for uniting subscribers for conversation including a testing-plug, connected thimbles for the jacks of each line, the said test-plugs being provided with tip and sleeve portions, the sleeve portions being adapted for connection with the test-thimbles when inserted, an operators telephone appliance, a listeningkey for connecting same with and disconnecting it from the cord-circuit, a coil portion it in inductive relation with the secondary of the operators telephone appliance, a

battery connected between one terminal of the said coil portion and the sleeve-strand, the remaining terminal of the coil portion being adapted for connection with the tip of the testing-plug upon the operation of the listening-key, a second coil portion also in inductive relation with the secondary coil of the operators telephone appliance adapted for inclusion in a subscribers telephonic circuit, and a clearing-out indicator included in circuit with the battery and the sleeve of the testing-plug, substantially as described.

3. In a multiple-switchboard telephone-exchange system, the combination with a plurality of telephone-lines extending from subscribers stations to an exchange, each telephone-line being connected at the exchange with jacks upon a number of sections of a multiple switchboard, cord-connecting apparatus for uniting subscribers for conversation including a testing-plug, connected thimbles for the jacks of each line, the said test-plugs being provided with tip and sleeve portions, the sleeve portions being adapted for connection with the test-thimbles when inserted,an operators telephone appliance including inductively-related primary and secondary coils, a listening-key for connecting the same with and disconnecting it from the cord-circuit, a battery interposed between the primary winding and the sleeve of said plug, and a conductor connected between the terminals of the primary winding and adapted for connection with the tip of the test-plug upon the operation of the listening-key,said

listening-key serving to include the operators telephone appliance in circuit with the sub scribers line, whereby a portion of the primary winding may be included in the testcircuit while the entire primary winding may be included in circuit with a subscribers line, substantially as described.

4. In a multiple-switchboard telephone-exchange system, the combination With a plurality of telephone-lines extending from subscribers stations to an exchange, each telephone-line being connected at the exchange with jacks upon a number of sections of a multiple switchboard, cord-connecting apparatus for uniting subscribers for conversation including a testing-plug, connected thimbles for the jacks of each line, the said test-plugs being provided with tip and sleeve portions, the sleeve portions being adapted for connection with the test-thimbles when inserted, an operators telephone appliance including inductively-related primary and secondary coils, a listening-key for connecting the same with and disconnecting it from the cord-circuit, a battery interposed between the primary winding and the sleeve of said plug, a conductor connected between the terminals of the primary winding and adapted for con neetion with the tip of the test-plug upon the operation of the listening-key, said listeningkey serving to include the operators telephone appliance in circuit with the subscribers line, whereby a portion of the primary winding may be included in the test-circuit while the entire primary winding may be incl uded in circuit with a subscribers line, and a clearing-out indicator included in circuit with the battery and the sleeve of the testingplug, substantially as described.

In witness whereof I hereunto subscribe my name this 27th day of October, A. D. 1900. HARRY G. WEBSTER.

Vfitnesses:

CHARLES A. BROWN, CHARLES E. HUBERD,

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