US578992A - Multiplex telephony - Google Patents

Description

(No Model.) 3 Sheets-Sheet 41.

s. W. HOLMANQ MULTIPLE TELEPHONE..

rra-578,992. I Patented Mmm, 1897.

(No Modem 3 Sheets- Sheet 2.

S. W, 'HMM-AN. MULTIPLE rlzlmolxmH mamma Patented Mw. 16, 1897.

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524% @SQL/M 3 Sheets-Sheet 3. ES. W. HULMAN.

MULTIELB TELEPHONE.

(No Model.)

` atented' M NVENTD R.

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@VMM f number of 'metallic circuits,'to increase the number of such circuits -without adding to IO` E [shorter intermediate`circuits,orq1 may obtain from two long circuits an additional'long I'S 'in every respect as if` they were all original v the two windings in series and yetV readily of two otherwise unequal undulatory curf constructed for use in practicing myinvenfiltriprovements yin Multiplex Telephony, of which the followingis a-specific'ation.

' UNITED STATES PATENT OFFICE.

SILAS 7.v HOLMAN, OF BOSTON, MASSACHUSETTS.

MULTIPLEX TELEPHQNY.

- 's rncrrrcarron rormingapm of Letters retenant. 578,992, dated March l1e,A 1897.

Applieation'iiled May 31, 1893- To all whom it may concern.: E,

` Be it known that I, SILAS W.A HOLMAN, ref siding at Boston, in the county ofSuEolk and Statenf- Massachusetts, have invented certain The object of myinvention is, with 'a given the number of wires. i By the use of my invention I may obtain' from two long circuits an additional series of circuit, or from aseries of shorter circuits, I may obtain one or more additional longercircuits.` While none' ofthe circuits, are de creased inefficiency, the longer added circuits are more eiicient than are original circuits o f the same, length. All. of the circuits, whether'original oradded, `may be operated circuits, each withl a separate pairof wires.

.A special feature of my invention is the use of a double-wound electromagnetic impedance-'coil whichiis separate'from and ad-V ditional to the transmitting and receiving in-` struments, bntwhich is hrei nafter more fully described, whose peculiar usefulness ,arises in part from4 the fact that itl isimpermeable to telephonecurrents tending to pass through permeable to telephone currents passing through the two ,windings in multiple and in part from the fact that it acts as an equalizer rents passingthroughtbe two windings inl. multiple. VIn the drawings, Figure l is a vdiagrammatic view of the double-wound electromagnetic impedance-coil used in practicin'gmy invention. Fig. 2shows an alternative methodof windingthe coil that is equally efficientl and more convenient in construction; ',Fig. l 3 is a perspective view-of the coilas actuallyv tion. 'Fig 4F` is a diagram showing how two telephoneLcircuits are arranged from four parallel wires in the mannerheretofore generally in use. Fig. 5 shows two long and two shortltelephonelcircuits contrived from the'V same four parallel wires according to my Vin- `Serial No. 476,090. (N0 model.)

I vention. Fig.v 6 shows three long telephonecir'cuits contrived' from the same four wires accordin g tomy invention. Fig. -7 shows one added long telephone-circuit contrived from;

aseries of short local circuits according to my invention.

The same letters designatelike parts in the same `or dierentl figures, numerals-being added to the letters to indicate the'different`- l parts of the same kind.

ThusT represents a telephone; L, 'a line@ l wire X, adouble-wound electromagnetic im- 4pedance'.coi1;'M, a magnetic core; w, a'wire wound upon a core, and j a junction 'between two wires. t Y. V

' In order that the invention may be fully understood, it is convenient tofirst describeV the double wound electromagnetic impe.-

dance-coil, which plays so'importanta part in practicing the invention..

Referring to Fig. 1, M isa magnetic core. wf 102 isa wire wound aroundthe core inon'e direction, (sayleft-handed,) and w3 w* a similar wire wound around the core in the opposite direction,(sayright-handed.) In^prac tice each winding should have a1 large uum` ber'of turns, so that alone and without the other it'would present a 'considerablleimpedance to a telephone-current. If it is desired that the ohmic `resistance of the coil shall `not be large, wire'of large sectional area' should be used. In practice, also, the core should consist' of lair-annular bundle of soft-iron wiresto increase the impedance, as shown in Fig. V3. Thebobbin maybe intwo parts for convenience of construction. Each bobbin, however, has two separate windings, asv shown in Fig. 1. i Thef` peculiar usefulnessof this `coil arises from theLfact that itsl self-induction 4is so'zlarge as to practically prevent the iiow of telephone-currents through the two windings in series,v while the mutual induc-A tion of they two -windings is such that it practicallyfannuls the eiect of the .self-induction of the single coils 4when a currentV tlows -equally. through thetwo windings in multithe coil does not/act asa transmitter or receiver, but asian equalizer of two otherwise unequal telephone-currents passing through' the two windings in multiple, tending to iu crease the lesser current and to decrease the greater without material loss of energy. Thus if the telephone-current passing over. the path w' 'wz were somewhat greater than.. th'e telephone-current passing over the path 'L05 w1 the eect of the coil as a whole would be to diminish the stronger current and in# crease "the weaker current until -they become equal. This equalizing eectof course ex? lrends within limits to whatever circuit thel windings w' 'w21 and 105 104 may be connected with, so that we have here an instrument capable of equalizin'gtwo otherwise unequal telephonecurrents fiowin g, for instancemponf two parallel telephone-line wires.

For convenience of. construction I may wind the twowires side by side about each portion .through the two windings in.- multipla-15.19;',

so that two equal currents, whether constant, intermittent, or variable, flowing through the two windings in, multiple shall exert equal and opposing magnetizing forces not only on the core as a whole, but upon each portion of the core. In proportion as the above-desiderata are attainedy will the beneiits of this feature o f my invention be realized.

For convenience in studying the remaining diagrams -I have designated the above-de-v scribed doublewound electromagnetic impedance-coil bythe letter X.

Having thus described the method of construction and properties of the double-wound electromagnetic 'impedance-"coil, it remains to l show how I make useof it in practicing my invention.

Fig. 4 shows four parallel line-wires connected to form two m etallic telephone-circuits in the manner heretofore generally in use. The two line-wires L' and L2 form one metallic circuit for the two telephones T and T2,

' and the two line-wires L11 and L1 form a second metallic circuit for the two telephones T3 and T4.

Fig. 5 shows hom-bythe use of my invention', we may contrive two long and two short telephone-circuitsfrom the same four linewires, here designated L5,L1, L7, and L5. i

is a double-wound electromagnetic impedancecoil,such as is above described, inserted in lines L5 and L, as shown. As this coil is impermeable to a telephone-current tending to pass through the two windings in series,

the lines L5 and L6 are divided by it linto two telephone-circuits T5 T5 on one side and T7 TB on' the other, and an inspection of the dialgram'shows that while conversation may be carried on between T5 and T6 or'between T7 and T.S no communication is possible between 2T5 or T ontheone hand and T7 or T8 on the other. Telephone T9 is in communication ,with telephone T1o by the line-wires L7 and L8. Let us 'next see how telephone T11 is put multiple, (hence without impedance). leaves the line'wires at j5- and je, passes through X1? in multiple, through 'telephone T12, through coil X5. inmultiple, over lines- L7 and Ls in multiple, through coil X1 inmultiple, back. Thecurrent from T11, arriving' at j' and jz, hasmo to itsvstarting-pointI in telephone T11.

eiect on telephone T5", because it charges the two junctions j' and4 t72 to the same potential.

For the same reason `it has-no eiect on telephones T, T7, T5,'T1, and T10. Moreover, lif the lines yL5 and L5, becausey of lslight electrical inequality, should not otherwise carry equal telephone-'cu rrents away from or toward junctions -j' 'and j, the coil X1-will .react on these lines to make the currents equal, in the manner above=,described. In the same way7 coil X has anreq-ualizing eect on currents at thetwo terminals of T6 and also on` the two f terminalsof T7, as also` coil 'X1-1 equalizesthe coil X5 those of telephone T111, and coil X1 vos' potentialof the terminals of telephone T11,

those of telephone T1. In fact these various coils act together to remove any inequalitiesof potential between lines L5 and L6 or be.

tween lines L7 and LE1 which might come from slight differences of conductivity, capacity,

insulation, or self-induction on -these linewires.

Fig. 6 is in all respects like Fig. 5, excepting that there is no intermediate station. T13 and T1'1 are in communication over lines L17 and L10, T17 and T15 over lines L11 and L15, and T15 and T16 are in communication over lines L9 and L10 as one side of the circuit and over lines L11 and L12 as the other. The added circuit T15 T111 is found in practice to be tele-l phonically superior to either et the original circuits 'T13 T11 or T17 T15. This I suppose to be due .to the facts that the resistance and greater than the capacity between eitherv original pair of wires.

Fig. 7 showsa long telephone-circuit T25 TA71 contrived from a 'series of shorter circuitsviz. T319 T and'T 21 T22 forming one branch anu T2 T26, T27 T28, and T29 T30 the other branch. As in Fig. 6, the long circuit T23 T24 is elec trially superior to an original circuit of the same length and of course superior per mile to the shorter circuits here shown. f

VInspecial cases -it may be desirable to employ a single conductor or even the earth in ,place of a metallic cireuitforming on e' branch of an addedV circuit. Thus in Fig. .5, for eX- `ample, the telephone-circuit between T11 and T12, which passes from T11 to T12 over the -path 'T11 X2 L5 L1 in multiple', X2, T12 might be returned from T12 to T11 by a single conductor or by ground instead of by the-pathxXf L7 L8 in multiple, X4, in which case the'telephonecircuit T9 T10 would of course be dispensed with.

I claimv 1. In combination .with two original metal lic telephone-circuits, each consisting of two conductors and a telephone at each end of each, an added metallic telephone-circuit consisting, at cach end, of a telephone, each terminal of which is connected in multiple withl y the two conductors of .one original circuit through two wires wound equally about each portion of a magnetic core, in opposite directions regarding currents which flow through the two windings in multiple.

2. In combination with an original metallic telephone-circuit, consisting of two conduc'- tors and a telephone at each end, an added telephone-circuit' consisting, at ,eachl end, of va telephone lone terminal of"`which is connected in multiple with the two conductors of one original circu-it through two wires wound equally about 'each portion of a magnetic.

core inopposi'te directions regarding currents which flow through the two windings in multiple, while the other terminal is connected to the corresponding telephone at the distant end by one or more conductors or by the earth.

3. In combination with two original metal lic telephone-circuits, each consisting of two conductors and a telephone at each end of each, two wires connecting the twoconductors of one original circuit to the two conductors of the other Yoriginal circuit, said wires bein g wound equally about. each portion, of a magnetic core in opposite directions regard'- 'ing currents which flow through the two wind- '.ings in multiple.

et. In combination with two original metallic telephone-circuits, each consisting of two conductors and a telephone at each end of each, an added metallic telephone-circuit consisting, at each end, of a-telephone, each terminal ofwhich is connected in multiple withthe two conductors of-one original circuit through the two windings of a differentially- -wound electromagnetic coil.

5. In combination with'an original metallic telephone-circuit, consisting 'of two conduc# tors and a telephone at each end, anl added telephone-circuit consisting,' at each end,- of

a telephone, one terminal of whichis connected in multiple with the two conductors of one original circuit through the two windings of a differentially-wound electromagnetic coil, while the other terminalis connected to the corresponding telephone at the distant end by one or more conductors or by.

the earth. i i

G.l In combination with two original metallic telephone-circuits, each consisting of two conductors and a telephone ateach end of ing and transmitting instruments connected therewith, and a differentially-wound electromagnetic coil which has its two windings respectively connected to the two conductors, and which acts as an equalizerof the currents Si:v In a line for'electrical communication, the combination of two'conductors; receiv- 'Iiowin g in multiple therein andnot as a trans 4 mitter or receiver.

In combination with two original metal lic telephone-circuits, each consisting of two conductors and a telephone at each end of each, an added metallic telephone-circnit consisting, at each end, of .a telephone, each termina-l of which is'connecte'd in multiple withl the two conductors of one original `circuit through two-wires wound equally about each portion of a magnetic core., in opposite directions regarding currents which ow through the two windings in multiple. 10.` In combination with an original metallic telephone-circuit, consisting of two conductors and a telephone 'at each end, an added telephone-circuit consisting, atV each end, ot a telephone, one terminal of which is -connected in multiple with the two conductors of one original circuit through ,two 'wires wound equally Iabout each portion of a magnetic core in opposite directions regarding currents which flow through the two windings in multiple,.while the other terminal is connected to the corresponding telephone at the distant end by one-or 'more conductors or by theearth.

In testimony whereof Ihave signed -my' name to this specification, in the presence of two subscribing witnesses, this 25th day of May, 1893'.

SILAS W. HOLMAN. Witnesses: WILLIAM W. JACQUES,

'.REBEN L. ROBERTS.:

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