US1401586A - Electrical searching-coil - Google Patents

Description

A. R. COMSTOCK. ELECTRICAL SEARCHING COIL.

APPLlcATloN man 1AN.24. 1920.

Patented Dec. 27, 1921.

il; :2122121231131 2..;122-'I` UNITED STATES ARCI-IIE R. COMSTOCK, OF MOUNT KISCO, NEW YORK.

ELECTRICAL SEARCHING-COIL.

Lacasse.

Specification of Letters Patent.

Patented Dec. 27, 1921.

Application filed January 24, 1820. Serial No. 353,872.

To all w from t may-concern Be it known that I, Anonm It. CorrsToC-ii, a citizen of the United States, residing at Mount Kisco, in the county of lVestchester.

tate of New York7 have invented certain new and useful Improvements in Electrical Searching-Coils; and I do hereby declare the following to be a full7 clear, and exact description of the invention, such as will enable others skilled in the art to which itappertains to make and use the same.

This invention relates to electrical coils and particularly to electrical searching coils which may be utilized to locate trouble such as short-circuits or grounds in wire communication systems, for example7 telephone lines, by means of inductive or other similar electrical phenomena.

Heretofore the approximate location of grounds and short-circuits in telephone or telegraph lines has been accomplished by means of the so-called Wheatstone bridge methods which are generally familiar. These methods are only approximate and require the lineman to travel from pole to pole within a certain area, in order to detect the ground or short-circuit. Frequently the approximation made in the local test room is not accurate and requires the lineman or repairman to make an extended search along the line in order to properly locate the trouble and repair the system so that it may be again utilized.

In accordance with this invention, substantially no approximations as to the location of a short-circuit or ground are necessary and the repairman or lineman may immediately proceed on foot or in a vehicle along a road which parallels the wire system, keeping within a distance of approximately fifty feet of the line until the ground or short-circuit is located by means of the searching coil. In this way it will be seen that by the use of the improved searching coil, a telephone, telegraph or other line which 'is supplied with an audible frequency alternating current may be followed with accuracy until a point is reached where the line is either grounded or short-circuited, thereby forming a. return path for the audible frequency currents.

The searching coil comprises a metallic core, a. primary winding of fine wire electrically connected to the core, and a secondary winding connected to the core and wound preferably at ight angles to the primary winding. A telephone receiver may be directly connected to the free ends ofvthe primary an'd secondary winding for the purpose of translating the audible frequency currents induced` or set up in the searching coil. or any convenient amplifying means may be inserted between the searching coil and the telephone receivers for the purpose of amplifying the induced or other currents set up within the coil in order that the coil may be ut-ilized at greater distances from the line or system or for other reasons as required by the lineman or repairman.

The invent-ion will be more clearly understood from the accompanying' drawings which illustrate an embodiment of the iii-j vention. In these drawings:

Figure l illustrates the method of utilizing the searching coil for the purposes of locating a short-circuit or ground in a telephone or telegraph system;

Fig. 2 illustrates diagrammatically the arrangement of the primar',7 windings upon the core of the searching coil;

Fig. 3 illustrates-a'convenient form of the searching coil for the purpose outlined in connect-ion with Fig. l;

Fig. 4 is a cross sectional view of the searching coil taken along 4 4 of Fig. 3; and

Fig. 5 is a` sectional view taken alongof Fig. 8.

Referring now to Fig. l, and assuming that the wires l and 2 have been supplied with audible frequency electrical oscillations at the central station, the lineman or repairman looking for the trouble in this system would follow the line carried by poles such as 3 and et, either on foot, or in a vehicle if the line parallels a road, and would keep a telephone receiver or receivers 5 connected to the searching coil 69 in an operative position over his ears. If the repairman or lineman follows the line and keeps well within the field set up by the electrical oscillations carried by the line, an audible tone will be heard in the telephone receivers 5 as a result of the currents induced or set up vin the searching coil 6. This audible note will continue up to the point 7, beyond which there will be no response in the telephone receiver. It is to be understood that the distance to which a repairman may work from a line and secondary iio may be increased bythe use of audible frequency current amplifying means and by the use of sensitive telephone receivers.

In Fig. 2, which illustrates the preferred embodiment of the searching coil, a core 8 of electrically conductive material is shown, upon which a primary Winding 9 of ne Wire is electrically connected to the core 8 at one end of the Winding, shown at the point 10. The secondary Winding 11 of the coil is also electrically connected to the core S at the point 12 and is Wound about the primary winding 9 at right angles thereto. The free ends of the primary and secondary Winding are shown at 13 and 141, respectively.

It has been found by experiment that a core of silver is preferable but cores of other electrically conductive metals such as copper or soft iron may be used. It has also been found that superior results are obtained when the secondary Winding of coarse wire is Wound at right angles to the primary Winding. The Wire forming the secondary Winding may be twice the diameter of the Wire forming the primary winding and good results have been obtained from a searching coil in which the ratio of primary turns to secondary turns is one hundred to one.

In Fig. 3 a completed searching coil 6 is shown which is suitable for placing in the pocket of a repairman or lineman and Which may be utilized in conjunction With sensitive telephone receivers to Work at a distance not greater than fifty feet from the telephone line which carries the audible frequency alternating currents. The free ends 13 and 1a of the primary and secondary windings of the searching coil are connected respectively to the binding poss 15 and 16 and which are in turn connected directly to the telephone receivers, or to the telephone receivers throu h suitable amplifying apparatus.

In` ig. 4 the arrangement of the searching coil 6 is shown within its moisture-proof lcasing 17 which entirely surrounds the coil and prevents the entrance of any liquid. This coating may be of Celluloid, rubber or other material having suitable insulating and moisture-proof properties.

In Fig. 5 the primary Winding 9 and the secondar f Winding 11 are shown `in their respective relations to the core 8; the casing 17 retaining the windings and core in a permanent position with respect to one another.

It is to be understood that while I have shown and described but one embodiment of this invention, that numerous modifications and arrangements of core, primary Winding and secondary Winding may be made Without departing from the spirit and scope of this invention.

-I claim 1. An electrical searching coil comprisingl a core of electrically conductive material, a primary Winding electrically connected thereto and Wound thereon, a secondary Winding electrically connected to said core and Wound thereon in an angular relation to said primary Winding.

'2. An electrical searching coil comprising a metallic core of highV electrical conductivity, a primary Winding Wound thereon and electrically connected thereto, a secondary Winding electrically connected to said core and Wound upon said primary Windingat right angles thereto. V

3. An electrical seaching coil comprising a core of silver, a primary Winding of iine Wire electrically connected thereto at one end of the Lsaid Winding and Wound thereon, a secondary Winding of'coarser Wire electrif cally connected to said core at one end of said Winding and Wound uponsaid primary Winding at right angles thereto. Y

In testimony whereof I aix my` signature.

ARCI-IIE R. COMSTOCK. i

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