US1930269A

US1930269A - Inductance device

Info

Publication number: US1930269A
Application number: US512297A
Authority: US
Inventors: Ralph M C Greenidge
Original assignee: Bell Telephone Laboratories Inc
Current assignee: AT&T Corp
Priority date: 1931-01-30
Filing date: 1931-01-30
Publication date: 1933-10-10
Anticipated expiration: 1950-10-10

Description

Patented 0.1.10, 1933 l v iffrcsoasai" H h a A mnUo'rAnoEpEvmE j Ralpli M. CQGi-eenidge,Chatham, ma as signor to Bell Telephone Laboratories, Incorporated, vNew New york Y orlJr, N. Y., a corporation of Application January 30, 1931.. Serial Nb. 512397 f [11 p 8 Claim's.'.(Cl.1'l 1- 24 2) i invention relates to inductance devices and more especially to such devices in which'the inductance" may be adjusted lor varied;

" The addition of loading inductances a t'ele-- phone lines to improve transmission has been carriedon'for a number of years in a manner which is well known in the art, both in the case of simple telephone linesand in the case of phantorn telephone systems; To provideagobd trarise '10 mission characteristics in a phantomed' system,

the two side circuits must be accuratelybalanced andconsiderable difficulty has been experiencedin properly balancingthe sideand phantom cir-" a cuitsespeciallywhere very exacting requirements '15 are placed upon the circuitsas'to transmission characteristics. Cross-talk between the phantom and side circuits is one ofv the "results of fan imperfect-balance or inductance, capacitance or re-;

7 s'istance. h This invention has as an object the improvementof the transmissioncharacteristics of tele- Phbn ir stion of cross-talk between side and phantom cirmm; g 4 A further object is the accurate loading of telephone lines." ,5

"3 0 phantom circuits cf'a telephone line."

.o f theelectrical"characteristics, namely,

capacitanceandinductance being byjtheir nature complementary; can be adjusted for bythe inclu-J I sion in the circuit of the correct value of either. "85; Generally, however,an inductance deviceis used.

.ffIh'e objects of thisjinveritionfare attained by, inserting auxiliary adjustable inductances in the circuits/associated with the main loading induc tan'ces';

Cent'to each other but separatedjby an air gap.

Amagnetic material armature is mounted in the airy gap and s, movable, t'owardand away from.

illustrating one form which: the invention may take and in which: y b I b r Fig. 1 is a top; view of amountingof a pair of auxiliary inductances for use with-phantom cir..

Each auxiliary inductance consistsof windings mountedon twoC-shaped coresso ar ranged that the free ends of the cores areadjae phantom telephonelcircu'it.

Referring now to Figs." 1 and 2' a base plate 5 of a non-magnetic and electrically non-conduc- I ENraq-OFFI'CEY Fig. 3 illustrates schematically the application tive material and of the 'general 'form shown is .10 may. beof brass or other tensilenoni-magnetic material so thatthere'is sufficijent spring I i V V action" to hold roan in position when iti's Another'object' of'this invention is the 'reduc snapped intothe portions. M

A member 12is provided as shown with a hole near the upper edge which is threaded'to-receive notches providedin the forked H b r v v v rod 11 substantially as shown.

A still further object isthe accurate balancing H of the electrical characteristics of the side and.

Piece 12 supports armature 13 of magnetic ma 'terial as fshown. Armature 13 is fastened to piece 12 in any suitable manner. As indicated in the drawing, a slot-'m ay'be cut along the" loweredge of piece l2 and'the armature forced; into the slot.

The dimensions of armature 13 are'such that there is but slight clearance between its free edges and; the bottom and sides of the recess in plate 5.

Coils

14 and 15 mounted on'cores 16 and 1'7 are forcedinto the recess and are hel'din posi tion by the friction between the sides of the recess and the outside of the coil structures and between projections? and 8 and the inside of the coil structures;- Ah, adhesive may be used to increasethis friction, or a'clamp may be used.

Leads

18, 19, 20 and 21 provide the means for connecting the coils to external circuits. v

The coils and'armature are positioned so that the armature is in a plane parallel to thejplanes of the free'ends of cores 16"andl'7. With the structure as just described, if rod 11 is turned about its axis by means of a screwdrive'r or similar tool, armature 13 is caused to 'movein a plane parallel to the plane of the freeends'of the cores and approaches the} free ends of one of the cores while receding from'the others. a The reluctancesof the magnetic paths through the cores are changed due-to the yarying air lio gaps and hence the inductances of the coils are changed.

The use of the device of this invention is a loaded phantom circuit is shown schematically in Fig. 3. This is the well known phantom circuit arrangement consisting of one phantom circuit and two side circuits. The two

side circuits

22 and 23 form the sides of the phantom circuit. The repeating coils for such a circuit are shown generally at 24 and 25, the loading coils for the side circuits are indicated at 26 and 2'7, the main phantom circuit loading coils are indicated at 28 and the auxiliary adjusting coils at 29. It is to be understood that the auxiliary coils 29 may be used in the side circuits as well as the phantom circuit.

No further description of the circuit is believed necessary. It is also believed that it will be readily apparent that if the phantom loading coils are slightly unbalanced, such unbalance is easily taken care of by changing the location of armature 13 relative to the free ends of the cores of the auxiliary inductances. This is done by turning the screw 11.

The device as described will adjust for inductance or neutralize capacitance unbalance, in the circuit. To adjust for resistance unbalance one of the leads of the pairs 18-19, 20-21, is left somewhat longer than necessary and by means of a clip connector the correct length of the lead is determined. The surplus length 01' the lead is cut off and connection made to the external circuits.

After the adjustments have been made, a cover of a non-magnetic and preferably non-metallic material isplaced over the device and any extra length of lead required to efiect the resistance balance may be folded and secured beneath the cover.

With devices such as described variations as high as microhenries have been obtained. This is sufiiciently large to adjust for any variations met in practice. As to resistance adjustment, practically any variation can be obtained but usually not more than .08 ohms adjustment is required which can be obtained as outlined above.

The advantages of the present device can be better appreciated when it is realized that for-- 1 merly adjustments were made by adding lumped struction avoids capacitance unbalance and the simple resistance adjustment is necessarily very small and can readily be made in the manner that has been pointed out. One such device having permalloy dust cores which has been found very satisfactory has the following overall dimansions-length 3 width about 1 /2 and a height of about It is to be understood that, whereas the present invention has been described in connection with the loading coil of a phantom circuit, it is not to be limited to such use, but may be applied wherever adelicate inductance adjustment is required without changing. the other electrical characteristics of the circuit.

The specific structure of the invention as described may be modified without departing from the spirit and scope of the invention as defined in the appended claims.

What is claimed is:

1. A variable inductance device comprising a plurality of main windings, a plurality of auxiliary windings, each one of said auxiliary windings connected in series with and adapted to cooperate with a specific one of said main windings,

and common means adapted to vary the inductance of certain of said auxiliary windings in one direction while simultaneously varying the inductance of certain others of said auxiliary windings in the opposite direction.

2. A variable inductance device comprising a plurality of main windings arranged in pairs, a plurality of auxiliary windings also arranged in pairs, each pair of said auxiliary windings adapt- .ed to cooperate with a specific pair of said main windings, and means adapted to vary conversely the inductance of said auxiliary windings in pairs.

3. A variable inductance device comprising a plurality of main windings arranged in pairs, a plurality of auxiliary windings also arranged in pairs, each pair of said auxiliary windings adapted to cooperate with a specific pair of said main windings, and means adapted to increase the inductance of one winding of an auxiliary pair while simultaneously decreasing the inductance of the other winding of said pair.

'4. A variable inductance device comprising a plurality of main windings arranged in pairs, a plurality of auxiliary windings also arranged in pairs, each pair of said auxiliary windings adapted to cooperate with a specific pair of said main windings, and means adapted to vary conversely the reluctance of the magnetic circuits of said auxiliary windings in pairs.

5. A variable inductance device comprising a plurality of main windings arranged in pairs, a plurality of auxiliary windings, also arranged in pairs, each pair of said auxiliary windings adapted to cooperate with a specific pair of said main windings, magnetic material cores associated with said auxiliary windings, a magnetic material armature for each pair of said auxiliary windings, and means adapted to vary the position of said armature relative to the endspi said cores.

6. A variable inductance device comprising a plurality of main windings arranged in pairs, a plurality of auxiliary windings also arranged in pairs, each pair of said auxiliary windings adapted to cooperate with a specific pair of said main windings, magnetic material cores for said auxiliary windings, the cores of each pair of said windings being arrangedso that their free ends are adjacent each other, an armature positioned between the free ends of each pair of cores, and means adapted to move said armature toward the free ends of one core and away from the free ends of the other core.

7. An inductance adjusting coil for use in connection with main inductance coils, said adjusting coil comprising auxiliary inductance windings mounted on C-shaped cores, each of said auxiliary windings adapted for connection in series with a specific winding of one of the main inductance coils, said auxiliary windings arranged in pairs, an armature for each pair of auxiliary windings, and means to move said armature toward one C-shaped core of a pair while simultaneously moving it away from the other core of the pair whereby the inductances of the windings of the pair are conversely varied.

8. In combination witha main inductance coil having a pair of windings, a variable inductance other, a piece of magnetic material mounted between the tree ends of each pair of cores, and means adapted to move said piece of magnetic material toward the Iree'ends of one core or a .pair and away from the free ends of the other coreot the pair.

. RALPH M. C.