US940994A - Telephone system. - Google Patents

Description

I. N. WALLACE.

TELEPHONE SYSTEM.

mncnlon FILED MAR. 22, 1 09.

Patented Nuv. 23,1909.

M MM. ,m m

JoHir N. wALnA'ca-or LA cnossn, WISCONSIN, Assmnoa TO vozrn nnnenn COMPANY,

'I To all wlwm concern:

or LA v ciaossri, WISCONSIN.

TELEPHONE SYSTEM.

- Be it known h JOHN N; WALLACE a subject-of the King of England, and a resident ofLa Grosse,-county of La Crosse, and Statebf Wisconsin, have invented anew and useful Improvement in Telephone Systems,

of which the following is a specification.

' invention pertains. to telephone sysjtemsusing'visu'al signals of the lamp type,

as used in telephone switchboards, and it comprises animprovement in such systems,

whereby "inmy improved system the signal is adapted in itself torespond directly to variant conditions of control whlch heretofore'have required auxiliaryor additional -duced at firstinto the telephone switchboard as a visual signal-for the operator, it was applied by including the hel x of a relay in the controlling circuit and relaying the control by means of contacts controlled by the helix, whereby the lamp and contacts and.

the source of current could be included in a circuit local to the central office, all such cirternal conditions of the main circuit to which the signal pertained, and of which its controlling helix' formed a component part.

This-method ,of contrdlling the lamp filashall fall within rather narrow limits. current may be produced only by potentials nient'was necessarybecause the lamps were notlada ted to operate successfully when included directly in circuits which might be closed through widely varying series resistances. h

The carbon lncandescent filament requires far its proper illumination a current which which fall within still narrower limits, since ,.i the carbon filament itself manifests the i when subjected to an increasing elec-.

characteristic of a decreasing reslstance I tromotiv'e force. Furthermore, the variation-of the illumination, is greater than the] variation of the current, and has Specification'of Letters Patent. Applicationfiled March 22, 1909. Serial No. 484,871.

This

, P atented' Nov. 23, 1909.

a still higher ratio to the. impressed petential; the carbon filament incandescent lamp included directly in circuits with Vanable series resistance having widely variable values therefore became an inadvisable application of the device. Particularly was this limitation felt in connection with the carbon filament lamp for use as a'li'ne signal where lines approached considerable resistances,- because of the ossible accidental -short-circuiting of the lines within or near the central office, which action would reduce the external line resistance to zero and give to the carbon filament of the lamp substanquently destroying them on the first occa-' sion. In connection with the use of the carbon filament incandescent lamp for signal-- ing purposes in such circuits, so calledbaL lasting in two ways has been resorted'to. The first method of ballasting is the inclusion in'the circuit with thelamp and adj acent to the lamp, or betweenthe source of potential and the lamp, of adead'resistance tially the entire potential of the central oflice source of energy. This resulted in reducing the life of lamps so subjected, very freso high that the resistance of the external and variable portion of the circuit would become negligible, or would-produce at most a maximum current variation in the circuit which Wouldfa-ll within the limitations of the current-carryingcapacity of the lamp filament. The objection to this method of ballasting resistance. From.7 5% to 90% of the total energy used for signaling purposes is required as a ballastingloss in such an arrangement. g I The second method of ballasting is to include in series with the carbon lamp a ballasting resistance manifesting to a high degree the characteristic of, an increasing resistance when suo ected to an increasingelectromotive force,

Such a ballast offers 5 resistance, but ofiers a higher resistance when the external variable resistance is low,

by reason of the higher drop of potential across the ballast under such a condition.-

An arrangement of this second method of ballastmg comprises merely an iron filament in series "with the carbon filament, both preferably in vacuum,, in. order that the iron filament may attain incandescence withoutcombustion.

In my improved,signalingsystem for tele-.

phone exchanges, Iprovide, in connection with the signaling and switching circuits of the telephone system, an incandescent lamp filament manifesting within itself the characteristic of presenting an increasing resistance to an increasing electromotiveforce, thereby manifesting w-ithm itself the.

characteristics heretofore obtained only by the conjunction of an incandescent filament and a ballast resistance of 'the second class, above described. Such an incandescent filament may be'formed of tantalum or tungsten, or metals manifesting similai' characteristics. The resistance of the lamp in my system of signaling preferably is high, in

order that the total variation bycontrol of the external circuit may be a minimum, thereby attaining also the advantages of the first mentioned method of ballasting but without the objectionable loss of energy,

since all energy is consumed in the signal lamp. j j

I illustrate the circuits of my invention in the figure accompanying, showing therein the simplest typical circuits in'which my invention may be embodied. It is obvious,

that in addition to the line circuit shown,

my invention may be applicable to many signaling circuits throughout the exchange installation. j p

In the figure, a circuit extends from earth through the battery Land the nietalliofilament of lamp 2, thence 'through contact of relay 3, and through line conductor 4, substation 5, line conductor 6, and remaining contact of relay 3 to earth. It will be seen that'the filament of lamp 2 is subjected to currents of minimum strength when the line is in good condition and the receiver at 5 is lifted, and that it is subjected to currents 'of maximum strength when for anyreason the conductors I and 6 are connected I at a pointnear the jack-7. The filament of the lamp-2 being a metallic filament, with a positive heat'co-etficient, will compensate.

to some degree by the variationof'its .own

resistance for any variation of the resistance in the conductors of the line. .I-

By insertion of the plug 8 in the-jack 7, i lay' twill the battery 9'will find, circuit throug% signal circuits in many instancesjw'ill' be I possible by the use of the combination of controlling resistances and a lamp having imam apositive heat co-eflicient in instances other illustration. Having thus described "States Letters Patent is: r

1. In aftelephone system, a line circuit containing a netallic filament lamp, and means for opening and closing said line circuit, substantially as described. 2. Ina telephone system, a circuit containinga metallic filament lamp and means for opening and closing the circuit, said circuit having variant resistance values when closed, substantially-as described.

3. I11 a telephone system, a battery; a metallic filament lamp; and a telephone line circuit in series therewith, substantially as described.

4. In a telephone system, a -line signal comprising a metallic filament lamp con- I nected directly between a source of potential and the switching devices of a line equipment, and included in a circuit with the line conductors, substantially as described.

5. In a telephone system, a line signal eluded directly in circuit with the line and sub-station equipment, substantially as de; scribed.

cient" of resistance and means for opening and closing the circuit,-said circuit'having variant resistance values when closed, sub stantially as described. i

7. In a telephone system, a battery; a signal lamp having a positive coefficient of resistance; and a telephone line; said elements in series, substantially as described.

8. In a telephone system, a line signal coefiicient of resistance and connecteddiswitching, devices of a Hneiequipment and tially as described.

- '9. In a telephone system, a' line; signal equipment, substantially as described.

alpluralityg of telephone lines to any one "of which any one of said lamps may-be connected in series with the line and the battery, substantially as described.

T 11. atelephone system, a plurality of telephone lines of variant resistances a pluthan the one specific case here. shown for j invention, what. I claim as new and desire to secure by United comprising a lamp having a positiveheat" comprising a signal lamp having a-pos'itive heat coeflicient of resistance and included directly in circuit with the-line and substation 1'15 '10. In telephone system, r plurality"of, signal-lamps, all alike, and having a positive "heat coeflicient-of resistance; a battery; and" comprising a metallic filament. lamp ino. In a telephone system, a circuit containing a lamp having a positive heat coeffi-- rectly between a source of potential and the included in series in a circuit with thelin'e conductors and substation bridge,substan-v rality of ianips (if uniform electrical'characteristics and having t positive heat e0efli-'- clent of resistance; and "a' battery j said 7 rality of lamps, and similar, and having metallic filaments; and asource of current; 10 each bf said lines being in series with one of said lamps and said 'source,--substantia11y as described.

Signed by me at La Crosse, county of La Crosse and State of Wisconsin, in the presence' of the two Witnesses.

. JOHN N.- WALLACE.

Witnesses: I

GUST.'.I. LUNDGREN, LOREN S. BEEs.

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