US1175111A - Means for preventing inductive disturbance in the test-circuits of telephone-switchboards. - Google Patents

Description

' l H. M BASCOM.

MEANS FOR PREVENTING lNDUCTlVE DISTURBANCE IN THE TEST CIRCUITS 0F TELEPHONE SWITCHBOARDS, 1,1?5 111,

APPLICATION FILED JUNEZI, 1915- Patentd Mar. 14,1916.

lnv ehta r Henry M Base-om,

To all whom it may concern:

panama srn rns PATENT W E 7 HENRY IVE. BASCOM, F BROOKLYN, NEW YORK, ASSIGNOR T0 AMERICAI AND TELEGRAPH COMYANY, A CORPORATION OF NEW YORK.

MEANS FOR PREVENTING INDUCTIVE DISTURBANCE IN THE TEST-CIRCUITS OF TELEPHONE-SFNITCHBOARDS. L

Be it known that I, HENRY M. 'BASCOM, residing at Brooklyn, in the county of Kings and State of New York, have invented certain Improvements in Means for Preventing Inductive Disturbance in the Test- Circuits of Telephone Switchboards, of

which the following is a specification.

In telephone central station equipment it is convenient to carry in proximity to one another, as in a common cable between the operators positions and the relay rack, the test conductors which join-the tips of the trunk operators calling plugs with the'back contacts of the busy test relays and the conductors which'connect the mechanical locking keys of machine ringing systemswith the windings of the tripping relays. 'By way of the capacities. between these two groups of conductors alternating current flows from the ringing generator through the trunk operators equipment to ground, producing noise in the receiver; To pre-. vent this is the object of'the present invention. I

In the accompanying drawing, Figure l W tend to be approximately equal," and, on account of their relation, the efiect ofthc represents diagrammatically a. telephone op- A erators equipment, and in much simplified -or schematic form those elements of the systhe repeating coil which I employ.

At an operators position A are situated calling plugs in which trunks terminate 'thesebeing here represented merely by tip contacts 10 of the group of plugs and test conductors 11 leading thereto. Mounted in the-usual manner atthe position are machine ringing'keys, conventionally indicated by contacts 12 to which are joined conductors 1.8. Each operator'has the customary telephone set, comprising :the receiver R and transmitter T, the receiver being in circuit with the secondary winding 14 of a repeat in-g induction coil or connecting device I.

, From-the plugs and keys the conductors 11 and 13 pass through a cable G to the relay rack B, where are mounted the busy test.

relays-o and the tripping relays' rfl' 'Ihe conductors 13. receive alternating current through the windings of the stripping relays from a ringing generatonG. Thecon Specification of Letters Patent.

secondary winding 14..

test relays, in accordance with this --inven tlon, are connected alternately in multiple 'rnnsr ndnn Patented Mar. 14L, 191%.

Application filed June-21,1315. Serial mi. 35,328.

by twoconductors 16 and 17 to primary WindihgslS and 19 respectively,.of the repeating coil I1. Thewindings or. this coilare: arranged upon the core 20v and differ entially connected, as is particularly-illustrated-in Fig.-. Qof'the drawing, s0 that curv I rents flowing at the same time in the pri- 1 Y maries 18 and 19 produce equal and opposite effects uponthe core 20, and thus neutralize one another as regards thelr action upon the .lonsidering alternating current flowing from the generator in. one or more'of the conductors 13, it will traverse the capacities between said conductors andthe conductors 11 in the cable C,'back contacts 15 of relays r-which are notat this time energlzed as a result of the use of the trunks for connectlons, conductors 16 and '17 and primary primaries from the alternate connections disturbing current upon the secondary winding is neutralized, and inductive disturbance in the -'operators receiver R from this source is practically eliminated. Save-as above described theelements or" the system act in awell known manner and will therefore not beconsidered further.

Having thus described my invention, 1 claim nation with a' plurality of test conductors exposed toinductiveldisturbance, of an oper so 1. In a telephone switchboard, the combi- ,atorstelephone,.and a connecting device sit- .uated-between said plural conductors and the telephoneand including means whereby the inductive efiects are'neutralized.

2. Ina telephone switchboard,the-combi nation with a pluralityof test conductors exposed to inductivedisturbance, of an option between said plural conductors and the telephone in which theinduced disturbing currents oppose one another.

3. In a telephone switchboard, the combination witha plurality of test conductor's erators telephone, and an inductiveconnecexposed to inductive disturbance, of a, re-

ary winding, and an operators telephone in circuit with the secondary winding.

4. A switchboard cable containing a group of test conductors and a conductor carrying disturbing current, a repeating coil having two pr1mary windings to which the test conductors are alternately connected in multiple and a secondary winding, the primary windings being arranged to produce opposite inductive effects in the secondary winding, and a telephone connected to the secondary winding.

In testimony whereof, I have signed my name to this specification in the presence of two subscribing witnesses, this'ninet'eenth day of June, 1915.

HENRY Witnesses:

JOSEPH A. 'GATELY, JOHN B. HYNES.

M. BAs'coM; a

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