US1647383A - Regulating means and circuits - Google Patents

Description

Nov. 1, 1927. 1,647,383 H. w. ULRICH REGULATING MEANS AND CIRCUITS 3 Sheets-Sheet i Filed Dec. 24. 1920 T Y il by MM/w Nov. 1, 1927. 1,647,383

H. W. ULRICHv REGULATING MEANS AND CIRCUITS Filed Deo- 24 1920 5 Sheebs--Sheei'I 2 M111 I E f7?. 2f 1 Y{Shasta-sheet :s

Nov. l, 1927.

H. w. ULRICH REGULATING MEANS AN CIRCUITS Filed Deo. '24 19'20 Patented Nov. 1, 1927. Vi

UNITED STATESl PATENT OFFICE.

HORACE W.j ULRICH, OF EAST ORANGE, NEW JERSEY, ASSIGNOR TO WESTERN ELEC- TRIC COMPANY, INCORPORATED, OF NEW YORK, N. Y., A CORPORATION OF NEW YORK.

REGULATING MEANS AND CIRCUITS.

Application led December 24, 1920. Serial No. 433,024.

This invention relates to regulating means and circuits and more particularly it relatesv to means for regulating vthe transmission equivalent of a signalling circuit.

The principal object of this invention is to Lprovide suitable means for regulating the transmission equivalent of a signalling circuit regardless of variations in the conditions aecting the electrical characteristics of the circuit. Other and further objects will be apparent from the description of the invention hereinafter given.

In general the transmissin equivalent of a circuit varies due to a number of dilerent causes. Among these causes may be en umerated variations' in the resistance, inductance or capacity of the signalling line or cable, the impedance of the loading coils, va-

riations inthe potentials of the repeater cir cuit batteries, etc.'

The present invention contemplates eliminating the effect of these variations by varying some adjustable element of the transmission circuit`in such'a manner as to compensate for the -undeslred varlatlons. In the caseof a'four-wire, repeater circuit effects due to all possible variations in the two sides of the four-wire circuit may be comensated for by varying the like elements f1n the two sides ofthe circuit on the ascauses of variation in either side.

This invention will be hereinafter described in detail in connection with fourwire repeater circuits in which a single regulating vsystem is employed Simultaneously to maintain constant the transmission equiyalent of a plurality of four-wire repeater circuits on the assumption that the four-wire circuits are similarly affected by themeans producing the undesired'variations. Such an assumption would be true, for example,

if compensation were desired for changes in the impedance in the four-wire signalling lines due to changes in temperature.

'In A. B. Clark Patent 1,438,219,1Decem'- ber 12,' 1922,. an arrangement isdescribed and claimed in which the regulation .of a four-wire circuit is obtained `by* associating a pilot circuit with therepeater circuits vto 'be regulated -Tle pilot circuit', is employed -the opposite direction.f

as an arm of a normally balanced Wheatstone bridge and selector switches responysive to an unbalanced condition 'of 'the compensating bridge serve to produce l.changes both in the Wheatstone bridge and 1n the four-wire circuits to be regulated.

This invention constitutes an improvement of the system of the Clark patent mentioned above in that a galvanometer of special construction yis made responsive to an unbalanced condition of the Wheatstone bridge to operate a clutch for rotating the switch arm to effectively cut` impedance elements in or out of circuit in such a way as to give the regulation desired. A second feature of this invention comprises employing a special automatic arrangement forinsuring the stopping of the regulating System whenever personal supervision is required, while permitting its continuous operation during normal variations in the resistance of the pilot wire. Still another'feature relates to employing'a plurality of pilot wires connected in parallel relation as an arm of theWheatstone bridge, whereby a considerable decrease is obtained in the amount'of resistance variation which must be handled, for example, by the regulating system for a given' range of temperature variation.

This invention will be better understood by reference to the following detailed description taken in connection with the accompanying drawings, in which Figures 1 and 2 when placed side by side represent the preferred embodiment of this invention adapted to regulate the transmission equivalent of a four-wire repeater circuit and Figure 3 represents the construct-ion in pers ctive of thev alvanometer by means of w ich the regulatlon is obtained. 4 E,

Referring to Figures 1 and '2 incoming line section 10 and 'outgoing line section 11g represent one side of a four-wirerepeate circuit for transmitting signals in one direction while the line sections 12 and. 13 may be used as the other side. of the four-wirev repeatercircuit for transmitting si nals in line sections 10 and 11 are two vacuum tube repeaters 14 and, 1 5 for producing the desired amount of.v amplification o f thesignals in that'fpart of the four-wire circuit includ- Included etween.

ing linesections 10 and 11.. Similar vacv y uum tube repeaters and 17 are connected No. 1,561,892, issued November 17, 1925, to

D. F. l/Vhiting.

Included between the output terminals of repeater 14 and the input terminals of repeater 15 is a gain adjusting potentiometer 18 which has a plurality of taps, any one of' which may be connected to the control electrode 19 of Vacuum tube repeater 15. The amount of amplification in that side of the four-wire circuit including the line sections 10 and 11 will, therefore, depend upon what tap of potentiometer 18 is connected at any particular time with the control electrode 19 of tube 15. The point of connection of control electode 19 to the potentiometer 18 is under the control of the plurality, of relays 20, 21, 22 and 23, only one of which is energized at a time. The energization of relays 20 to 23 is determined by the position of switch arm 25, the position of which, by mechanism hereinafter described, is determined by the unbalanced condition of a Wheatstone bridge arrangement. The Wheatstone bridge comprises two arms 26 and 27 of fixed resistance, a third arm comprising resistance 28 and that portion of the potentiometer wireI 29 included between point`30 and contact 31 and a fourth arm which comprises that portion of potentiometer wire 29 included between contact 31.

Iwhich lare connected in vparallel relation through switching ke s 35 and 36.

It isto be assume that pilot wire 33 is closely associated with the line sections 10 and 13 in such a way that variations in resistance of line sections 10 or 13 due to tem perature variations'will be accompanied by a corresponding change in the resistance of pilot wire 33. Similarl pilot wire 34 should be associated witg line sections 11 and 12 in such a Way that temperature variations produce corresponding eifects in line sections 11 and 12 and pilot wire 34. rlhese two pilot wires may, for example, each com-v prise a twisted pair of the cable, the other pairs of which are employed for transmis sion of signals, in which case the pilot wire, of course, would be adected similarly with the other pairs. 0

-Briey the. operation of the regulating system therefore consists in the temperature variation producinga change fin, the pilot wire resistancefwhich upsets the VVheatstone bridge and, by an arrangement hereinafter described, the unbalanced condition of the l-Vheatstone bridge rotates switch arm 25 to cause the energization of one of the relays 20 to 23 inclusive, thereby changing the connection of control electrode 19v to such a point on the potentiometer 18 that the transmission equivalent of the repeater circuit is made to be of the same value as it'had previous to thetemperature variation which produced the unbalanced condition of the lVheatstone bridge.

Before explaining in detail the operation of this invention it will benecessary to describe the structure and operation of the galvanometer and associated apparatus by means of which the unbalanced condition of the Wheatstone bridge produces the regulation desired.

Referring to Fig. 3, the galvanometer system 40 has a pointer 41 attached thereto, which, when the VVheatstone bridge is balanced, lies directly under the space between the ends of the two right angle levers 42 and 43 which are pivoted respectively at points 44 and 45. From this position of rest the galvanometer pointer may deflect, under the influence of a current passing through the galvanometer coil, until the pointer lies in any position between the stops 46 and 47 on the rocker arm 48. Rocker arm 48 is lpivoted at points 49 and 50.

Ell)

ever, as the rocker arm is raised, the galvanometer is unbalanced and its pointer lies under one of the right angle levers 42 or 43, the pointer 41, as it is raised, carries up with it, the horizontal arm of one of these right angle levers. The upward "movement thereby given to thehorizontal arm of one of the right angle levers, 43 for example, causes the vertical arm of lever 43 to press against the pin 55 mounted on an extension of the normally Ahorizontal arm 56 whereby the arm 56 is displaced from its horizontal position. 1

The effect of displacing horizontal arm 56 will be better understood by noting that the arm is supported by member 57 which is pivoted at the point 58, the horizontal arm 56 being pivotedto the lower end of the member 57. Horizontal arm 56 is, at times, kept in frictional engagement with a disk 60 mounted on a shaft 61, by means of a coiled spring 62, one end of which is attached to some rigid support (not shown), and the other end of which is fastened to an extension of member 57. The frictional enlll) gagement between arm 56 and disk 60 is periodically broken by means of a ca m 64 on shaft 52 which operates to produce the disengagement a't-the same time or a little before the upward movement of rocker arm 48 is produced by cam 51.

When, therefore, the galvanometer pointer is underneath the end of lever 43 and the upward movement against rocker arm 48 causes the lower end of right angle lever 43 to displace the normally horizontal arm 56, the arm 56 is not in engagement with disk 60 so that the tiltingl of the arm 56 does not affect disk 60. As soon as rocker arm 48 returns to its original position, cam 64 allows the normally horizontal arm 56 to engage disk 60. Immediately thereafter,

l .with arm 56 at this time, disk 60 is also rotated about equal to the distance. arm 56 was originally displaced by lever arm 43.

Mounted on the same shaft as disk 60, are a disk 70 (preferably of insulating material) and a contact arm 25. Included in a j groove on the periphery of disk 70 is the potentiometer wire 29 to which Areference has already been made in the discussion of u Fig. 2. Contact arm is adapted to make Contact with any one of a plurality of contact studs 71, 72, 73, etc. which are set in a stationary b 'ock 75 of rial. These contact studs 71,'etc., each lead to one of the relays controlling the adjustment of the gain adjusting potentiometer.

It is to be noted that the amount shaft 61 yis rotated to vary the position of contact arm 56 will be tilted. This action therefore,insures that the corrective action roduced by the galvanometer system wi be proportional to the change in the resistance of the pilot wire. f

Itis also to be notedthat forv positions of maximum deflection, galvanometer pointer 41 instead of cooperating with the right angle levers 42 and 43, engages in itsl upward movement with either one of the sup. plementary levers 77 and 78. The reason,

pointer41 for a large deiiection does not:

engage levers'42 or 43 is because levers 42 and ,-43 are hollowed out, near the points about which they are. pivoted, to such an extent that-,when rocker arm 48 is raised to its highest'positionpointerv 41 is still out of insulating matement requires personal supervision. The

adjustment of the galvanometer system is such that a deflection of the galvanometer pointer under one of the supplementary levers 77v or 78, indicates an abnormal condition in either the repeater circuitor the pilot wire system, as would be occasioned, for example, by the short-circuiting of apart or all of one of 4the pilot wires.

The `continuously operating shaft 52 on which are mounted the cams for lifting the rocker arm 48, disengaging arrn 56 from disk 60, and for restoring arm 56 to its normally horizontal position, may be driven by any suitable means. Herein it is shown connected by suitable gearing and 86 to a. motor 87. If desired, the frictional contact between arm 56 and disk 60 may be obtained by means of two cork blocks 88 and 89 which'arefastened to opposite ends of larm 56.

In .order to put`the regulating system in operation, thel two pilot wires 33 and34 by means of leads 90 and 91, should bc connected into the Wheatstone bridge by means of switching keys 35 and 36. The throwing over to operative condition of switching keys 35 and 36 energizes the relay B vby the following circuit-z from grounded battery, winding of relay B, conductor v91', contacts 92 of switch 36, and contacts 93 of switch 35 to ground. The operation of relay B.

closes the energizing circuit for the lVheatstone bridge by the following path: from point 94, conductor 95, battery 96, resistance lamp 97, movable contact 98 of relay B,

amovable contact 99 of the normally deenergized relay D' to thel spring contact 31 of the potent-iometer wire 29. The closing of this last'circuit therefore connects battery 96 between the midpoint of the Wheatstone bridge arms 26 and 27 and the mid-point of arm 28 and the fourth arm which comprises 'pilot wires 33` and 34.Iv

The operation of 'relay B also closes an energizing circuit for relay E over the followin pathrfromo -grounded battery, windingo relay E, conductor 100, movable contact 101 of the normally deenergized relay D, conductor 102, movable contact 103 of izo' relay B, conductor 104, and movable contact 105 of normally deenergized relay A, to ground. The energization of relay E causes its movablev contact 106 to close-the .switch arm 25 closes an energizing circuit for relay 21 by means of the following path: from grounded battery, winding of relay 21, conductor 110, conductor 111, contact 108, and switch arm 25 to ground. Relay 21 being energized pulls up its movable contacts and establishes the following connection: from control electrode 19, conductors 112 and 123, movable contact 114 of relay 21, and conductor 115 to point 116 on the gain adjusting potentiometer 18. Control electrode 19 by the energization of relay 21 is therefore connected to the approximate midpoint of the potentiometer 18. This is the position desired `for the average resistance of the pilot wires 33 and 34 since it allows the connections to the potentiometer 18 to be varied to give as much increase in the transmission equivalent of the circuit as it can be varied to decrease the transmission ,equivalent of the circuit. l

tion which produces similar effects in the impedance-of the pilot wires 33 and 34, such as an increase in temperature, for example. This increase in temperature would increase the resistance of line sections 10 and 11 thereby tending to decreafe the transmission equivalent of the repeater circuit. -Pilot wires 33 and 34, however, are similarly affected, and the increase in their resistance upsets the balance of the Wheatstone bridge, whereby they galvanometer suspension 40 is defiected.

1f, as assumed above, the change in the resistance amounts to an increase, the galvanometer pointer 41 will be defiected under the horizontal part of the pivoted arm ,42, and the upward movement of rocker 'arm 48 will cause pivoted arm 42 to press against the pin120 whereby the normally horizontal arm 56 is turned in a clockwise direction an amount proportional to the deection ofA the pointer 41. Subsequently, the large cams 66 and 67 will restore arm 56 to its horizontal position 4thereby rotating switch arm 25 over to the stationary contact 73, for exarm 25, contact 73, conductors 121 and 122,

and winding relay 22 to battery and ground. Relay 22 on operating closes the following connection between potentiometer 18 and Acontrol electrode 19: control electrode 19,

amount of potentiometer 18 included in the.

input circuit of tube 15 serves to increase the amount of amplification in line sections 10 and 11 thereby tending to compensate for the decrease in amplification produced by the assumed increase in temperature.

At the time switch arm 25 was moved to contact 73, the disk carrying potentiometer wire 29 was moved in a counter clockwise direction thereby increasing the amount of the potentiometer wire 29 included inthe l/Vheatstone bridge arm containing the pilot wires and at the same time increasing the amount of the wire 29 included in that arm of the bridge containing resistance 28. Thev regulating apparatus should be, so adjusted that if the increase in the .amount of potentiometer. 18 included in the input circuit of tube 15 is suflicient to completely compensate for the temperature increase, the change in' the relative proportions of the wire 29'ineluded in the pilot wirev arm 'and arm 28 should be such as to restore the balance of the Wheatstonebridge.

lf the changes in the connections for po. tentiometer 18 are sufficient to compensate for the temperature increase, the Wheatstone bridge will, therefore, be balanced again and pointer 41 will return to its position of rest. No further rotation of the shaft 61 will, therefore be produced until the Wheatstone bridge becomes unbalanced again.

lf, however, the change in the connections for potentiometer 18 did not compensate entirely for the increase in temperature, galvanometer pointer 41 will remain deflected under the horizontal part of the pivoted arm 42 and rocker arm 48 will again cause the pivoted arm 42 to press against pin 120 and tilt arm-` 56'in an amount proportional to the am-ount of deflection of pointer 41. The restoration of. arm 56 to horizontal position, will cause switch arm '25`t0 be' rotated farther in a counter clockwise direction and it may be assumed, for example, that it is moved until it vrests on contact 72. The breaking of contact between switch arm 25 and contact 73 .leenergizes relay 22. Switch arm 25 contacting with stationary contact 72 closes the energizin circuit for relay 23 which may be trace as follows: from battery, ground, winding of relay 23, conductors 127 and 128, contact 72, and switch arm 25 to ground. The energization of relay 23 by connections similar tothose previously traced serves to connect the control electrode 19 to the point 130 of potentiometer 18. It this change in the connections of potentiometer 18 is sulicient to compensate for the change in resistance of the four-wire repeater circuit, galvanometer pointer 41 will move back to its normal posit-ion of rest. If this last change in the connections of potentiometer 18 is not suiiicient to compensate for the change in resistance, still other relays 15, similar to relays 22 and 23 may be energized t0 connect still a greater portion of potentiometer 18 in the input circuit of tube 15.

It is to be understood, of course, that any number of relays, such as to 23, may be 2() employed. In one particular case it was found convenient to employ twenty-one relays, each of which controlled connections to a. diiierent point on the gain adjusting potentiometer.

If, on the contrary, a decrease in temperatureshould take placethereby decreasing the resistance of the pilot wires and the fourwire repeater circuit, the unbalance of the VVh'eatstone bridge would be in such a direction as to cause pointer 41 to be deflected under the pivoted arm 43 whereby switch arm 25 would be rotated ina clockwise direction. It will be readily understood fromcircuits previously traced, that the rotation of switch arm 25 in a clockwise direction whereby contact is made with one of the stationary contacts 132, 133, etc., that relays will be energized which will serve to decrease the amount of potentiometer 18 included in the input circuit of tube 15 thereby decreasing the ampliiication in line sections 10 and 11 and compensating for the decrease in resistance.

From the above description it will be apparent that the circuit arrangements described serve to maintain constant, the transmission equivalent of line sections 10 and 11.

The other half of the four-Wire repeater circuit may be simultaneously regulated by the same series of relays, 2O to 23 inclusive.

The gain adjusting potentiometer 134 included between tubes 16 and 17 is similar t-o potentiometer 18 and has a. plurality of points connected by leads through the lefthand contacts Of.- the relays to the control electrode of tube 17. It is apparent from the drawing that whenever, as above described, the amount of-potentiometer 18 included in the input circuit of tube 15 was changed to compensate for changes in resistance, similar changes mere made in potenti-' ometer 134 whereby compensation can be obtained for the change in resistance of line sections 12 and 13.

It is also'to be understood that the Wheatstone bridge of 2 may be employed to -and 11 or 12 and 13.

regulate simultaneously, a plurality of fourwire repeater circuits similar to the one comprising line sections 10 to 13 inclusive. The leads 135, 111, 121 and 128 may also be connected respectivelyfto conductors 136, 137, 138 and 139 which lead to the windings of relays similar to relays 2O to 23 inclusive which are represented by the block 140. The

relays of block 140 may be employed to control the connections for gain adjusting po.- tentiometers located in line sections 141, 142, 143, and 144. Blocks 145 and 146 may represent repeater apparat-us similar to the apparatus shown between the line sections 10 If at any time in the operation of the regulating arrangement, an abnormal change in the resistance of the four-Wire repeater circuits should take place, or if one of the pilot wires should inadvertently be shortcircuited, for example, whereby a large deflection of pointer 41 would be obtained, the pointer 41 would be deflected under one of the supplementary members 77 or 78. If,

for example, the pointer were deflected underneath the lever 77, rocker arm 48 would cause contact to be made between contacts 79 and 80. The closing of this contact as shown in Fig. 2 serves to vlight a lamp 150 and energize relay F by the followin circuit: from grounded battery, winding o relay F, conductor 151, lamp 150, and contacts 79 and 80 to ground. The energization of relayF may be employed for operating a buzzer 152 which will serve to call to the attention of the person supervising the apparatus that personal supervision is required. The lightring of lamp 150 will indicate to the supervisor the source of the trouble. The deflection of galvanometer pointer 41 underneath lever 78, will light' a signal lamp 153 and will also energize relay F to operate the buzzer.

Included in the arm 28 and the pilot wire arm of the Wneatstone bridge, are the two windings of the differential relay C. These two windings oppose each other in their action on the movable contact of relay C, and for a condition of balance in the Wheatstone bridge or a normal variation from the balanced condition, the windings are so adjusted that the movable contact of relay C is not pulled over to the stationary contact. If, however. an abnormal degree of unbalance of the Wheatstone bridge takes v place whereby the currents in arm 28` and the pilot wire arm of the bridge have quite dierent values, the contacts of relay C will be closed thereby energizing relay .A over the yfollowing circuiti from grounded battery, winding of relay A, conductor 156, and contacts of relay C to ground.

The energiz'ation of relay L serves to short-circuit the galvanometer suspension 40 by closing a shunt path of low resistance around the terminals of `the high resistance 157 which normally shunts the galvanometer 40. 'Ihe short-circuiting of galvanometer 40, of course, prevents-injury to the galvanometer 40 from the unusual currents which will otherwise flow therethrough reaks The energization of relay A also the energizing circuit for relay E which has been previously traced as passing through movable contact 105 of relay A. The bearking of the energizing circuit for relay E serves to stop the motor 87 and the pulling over of movable contact 165 lights a lamp 160 and enei/gizes relay F to operate ,buzzer 152.

Whenever, 1n the operation of the regui, tion. IAs shown in Fig. 2, the two end stationary contacts 160 and 161 are not connected to relays which control the connections for the gain adjusting potentiometers but are connected to windings of a double relay D. VVheneVer in the operation of the circuits, switch arm 25 is rotated far enough in either direction to come in contact with either contact 160 or 161, relay D will be energized from ground, battery, either conductor 162 or 163, a winding of relay D to either contact 160 or 161, and switch arm 25 to ground. The energization of either winding of relay D will serve to pull over Contact 101 thereby breaking the energizing circuit for relay E and stopping motor 87. The energization of relay D will also pull over movable contact 99 thereby disconnecting thesource of current 96 from the Wheatstone bridge. The regulator will, therefore, be inoperative until the necessary manual adjustments-have been made by the attendant torestore switch arm 25 to some contact located between contacts 160 and 161. As soonas switch arm 25 is thus moved, relay D will be deenergized, motor 87 started again, and the source of current 96 connected again to thexWheatstone bridge.

If the two pilot wires 33 and 34 do not happen to have the same resistance, the pilot Wheatstone bridge, the adjustable resistance F167 may be adjusted tobring the pilot wires, lfor example, up to the desired resistance.

In one case, forexample, arms 26 and 27 of rthe l/Vheatstone bridge each khad a resistance of 300 ohms, while the resistance 28 was 9350 ohms, the winding of relay C in circuit with resistance 28 was 200 ohms and half of the resistance of wire 29 was 225 ohms. With such values, the maximum resistance of the pilot wires in parallel can be about 9800 ohms for efficient operation. The maximum resistance of the pilot wire which may be handled eiiciently, is limited by the fact that it has not been found feasible to make potentiometer wire 29 have a greater resistance than about 450 ohms. An appreciable increase of the resistance of wire 29 by employing a smaller wire, for eX- ample, causes trouble in obtaining a good Contact between the spring contact 31 and the potentiometer wire. It has, therefore, bren found preferable instead of emlploying a single pilot wire to divide the pi ot wire in two and connect the parts in parallel thereby halving the effective resistance of the pilot wire arm of the bridge. In the case where the pilot wire resistance arm was of the order of 9800 ohms, and the pilot wire was divided and the parts connected in parallel, each part consisted of a twisted pair of No. 19 gauge cable, 125 miles long.

What is claimed is:

1. In combination, a signaling system comprising two line sections, a repeater therebetween, a pilot wire associated with each of said line sections, said pilot wires being connected in parallel and means responsive to a change in an electrical condition of said pilotl wires for regulating the transmission equivalent of said system. V

2. In combination, a signaling system comprising two line sections, a repeater therebetween, a pilot wire individual to each section, a normally balanced Wheatstone bridge, one arm of said bridge comprising said pilot wires connected in parallel, and means responsive to an unbalance of said bridge for regulating the transmission equivalent of said system.

3. In combination, a signaling system comprising two line sections, a repeater therebetween, an adjustable impedance .element so connected in said system that the transmission equivalent 0f said system may be controlled. by said adjustment, a pilot wire associated with each of said line sections, said 'pilot wires being connected in parallel, and

means responsive to changes in an electrical condition of said pilot wires to vary the adjustment of said element.

l4. In combination, a deflecting member, a source of power, a translating device, a pivoted member the movement of which by said source of power is controlled by said deecting member when its deflection is of the adjustment of a condition of said device,

a second translating device, and a second pivoted member the movement of which by said so'urce'of power is controlled by said deflecting member when its deflection is greater in vmagnitude than the first men-.

tioned deflection, the movement of said second pivoted member for controlling the adjustment of a condition of said second device.

5. In combination, a deflecting member, a source of power, a translating device, a movable member the movement of which by said source of power is controlled by said deflecting member when its deflection reaches a certain magnitude, the movement of .said movable member controlling the adjustment .of a condition of said device, said movable member being unresponsive to a defiection of a certain greater magnitude, a second translating device, and a second movable member the movement of which by said source of power is controlled by said defiecting member when its .defiection reaches the value to which said first movable -member is unresponsive, the movement of said second movable member controlling the adjustment of said second device to a certain condition.

6. In combination, a deflecting member, a source of power, a pair of pivoted members -oppositely disposed with respect to said dcf-lecting member, the actuation of one of said pivoted members by said source of power being controlled by a deflection of a cer- Y tain magnitudein the one direction of said deflecting member, a translating device the adjustment of which to a certain condition is controlled by the actuation of said one'of said pivoted members, said other pivoted member being similarly responsive to a deflection in the opposite directionand of a certain magnitude to produce a different adjustment -in the electrical condition of said device',V a vsecond translating device, and ,a

second pair `,of pivoted members oppositely being responsiv ing member to which said first pair ufl-pivdisposed with respectl to .sa-id deflecting' member, the actuation osaid second pair of pivoted members by said source of Apower d eections of said defiectoted membersv is unrespgnsive .and vconnections whereby the actuation'l of' 'said second pair of pivoted memberscontrol an electrical condition of Sad second'tran'slatng device.

'-7, In' combination,'afdeflecting member, a source of power, sa" plurality 0I stationary contacts, translating devices connect-ed to a 'plurality of said stationary contacts, a movable switch arm cooperating with sald sta- I tionary contacts for controlling the electrical condition of said translating devices, and

a pivoted member the movement of which venergized by said source of power for causing said deflecting memberl when deflected to contact withV said pivoted member and cause the movement thereof, said pivoted member having such a configuration as to contact-with said deflecting member only when the deflections of said deflecting member are of less than a' certain magnitude.

9. In combination,v an electrical circuit, a deflecting member responsiveto conditions vaffecting the electrical characteristics of 'said circuit, a plurality of stationary contacts, 'a movable switch arm cooperating with said contacts, means associated with said stationary contacts for controlling .an electrical condition of said circuit, la source of power, a pivoted member Athe movement of which controls the position of said switch arm, and means energized by said source .of power for causing said defiecting member when deflected to contact with said pivoted member to cause a movement thereof.

10. In combination, an electrical circuit, a deflecting member responsive to conditionsallee-ting electrical characteristics 'of said circuit, a plurality of stationary contacts, a

movableA switcharm cooperating withsaid stationary contacts, means associated with said stationary/ contacts `for controlling an electrical condition of said circuit, a source Y.of power, a pair of pivoted members oppositely disposed with respect to said deflect-- -ing member, saidv pivoted members being adapted to control the position of said switch arm, and means energized bv said source of power for causing said defiecting member when deflected to contact'with' one v of said pivoted members to cause a movement thereof whereby the position .of said switch arm is controlled. Y 11. In combination, a signaling circuit, means for regulating an electrical condition'of said circuit, said meanscomprising a` pilot wire associated with said circuit, la ri,

def-lecting `call condition o'fsaid pilot wire, a source of power, a pivoted member adapted to vary member responsive to an electri` 'I the transmission equivalent of said circuit, v

means energized by said source of power to V cause a movement of said plvoted member f when said deectingmember is de flected'a certain magnitude, a second pivoted member adapted to be moved by said last means when a greater deliection of said defiecting member occurs, an indicating device and means controlled by the movement ot said second pivoted member for operating said indicating device.

12. In combination, a normally balanced Wheatstone bridge network, a galvanometer responsive to an unbalanced condition of said bridge, and means responsive to an abnormal deflection of said galvanometer for short-circuiting said galvanometer.

13. In combination, a normally balanced Wheatstone bridge network, a deflecting member responsive to an unbalanced condition of said bridge, a source of power, a pivoted member, means energized by said source and cooperating with said detiecting member for causing a movement of said pivoted member, and connections controlled by a movement of said pivoted member i'or shortc'i.rcuiting said deflecting member.

14. In combination, an electrical circuit, a defiecting member responsive tovariations aiiecting the electrical 'condition of said circuit, a source of power, means for ad-y justing said electrical circuit, an arm periodically moved by said source and arranged to cooperate with said defiectmg member when it deflects a certain amount.

to control said adjusting means, and means responsive to an abnormal deflection of said defiectng member for rendering said source inedective.

15. In combination, a normally balanced Wheatst'one bridge network, a galvanometer res onsive to an unbalanced condition, of said ridge, a source of currentfor sald bridge, and means responsive to an abnormal defiection of said galvanometer for disconnecting said source from said bridge.

16. In combination, a normally balanced VVheatstone bridge network, a galvanom-l eter responsive to an unbalanced condition of said network, a source of current con-y nected between the junctions of opposite arms of said bridge, and means responsive to an abnormal deflection of said galvanometer for preventing saidsource from supplying appreciable current to said bridge.

17. In combination, a normally balanced VVheatstone bridgernetwork, a differential relay having windings in adjacent arms of said network, said relay being normally deenergized, an electrical circuit, moans responsive to an unbalance of said bridge for varying the electrical condition of said circuit, andconnections controlled by said rela for rendering said means inoperative wliienever the current in one winding of said relay becomes greater by a certain amount than the current in the other windino'.

18. In combination, an electric circuit, a plurality of stationary contacts, a movable yswitch arm cooperating with said contacts,

means controlled by variations in the conditions affecting the electrical characteristics of said circuit for moving said switch arm, connections from said plurality of stationary contacts for controlling an electrical condition of said circuit, an additional contact on either side of said plurality of contacts with reference to the movement of said switch arm, and connections controlled by the association of said switch arm with one of said additional contacts for rendering said first `means inoperative. l

20. In comblnation, a line, a potentiometer in shunt to `said line, a deflecting member responsive to change in the conditions affecting the electrical characteristics of said line, a periodically operating member adapted to engage said delecting member, a pivoted member actuated by said periodically operating member through said delecting member, connections controlled by said pivoted member for controlling said potentiometer, and means controlled by; a deflection of said detlecting member for restoring said deflecting member to its normal position.

21. In combination, a plurality of regulating elements, an electric circuit including a variable number of said regulating elements, a defiecting member responsive to change in the conditions aEecting the electrical characteristics of said circuit, a periodically operating member adapted .to engage said def'lecting member, a pivoted member actuated by said periodically operating member through said delecting member, connections controlled by said pivoted member for effectively removing from said circuit one of said elements and at other times for effectively removing another of' said elements from said circuit, and means controlled by a deflection of said deflecting member for restoring said deflecting member to its normal position.

22. In combination, a plurality of regulating elements, an electric circuit including a variable number of said elements, av deflecting member responsive to change of conditions afecting the characteristics of said circuit, a periodically operating member adapted to en age said deflecting member,

ivoted mem er actuatedby sald periodii. operatmg member through said delli() trolled by said pivoted member, a plurality of stationary contacts cooperatingwith said switch arm, and connections from said Stationary contacts for controlling the number of said regulating elements included in said circuit.

23. In a signalling circuit, transmission regulating means therefor comprising a gal- 'vanomter, a regulating element, and means for controlling said element by saidl galvanometer.

24.1In combination a signalling circuit, means for maintaining substantially constant transmission ofthe signals in said circuit, said means comprising a galvanometer, a regulating element in said circuit, and means for controlling said element by said galvanometen 25. In combination, a signalling circuit, transmission regulating means therefore comprising a galvanometer, aplurality of regulating elements in said circuit, and means for controlling said elements byv said galvanometer. y

26. In combination,l a signalling circuit, transmission regulating means therefor comprising a galvanometer pointer` responsive to change in a condition of said circuit, a periodically operating member adapted to engage said pointer, a pivoted member controlled by said pointer andsaid periodically operating member, and a regulating element in said circuit controlled by said pivoted member.

27. In combination, a signalling circuit, transmission regulating means therefor comprising a galvanometer, a pluralit of 'regulating elements in said circuit, anii. of relays controlled by said galvanometer for controlling said elements.

28. A regulating element, a motor `for driving said element, a Wheatstone bridge, means responsive to 'a condition of unbalance of said bridge Within certain limits for determining when said motor shall drive said element, and translating means responsive to a condition of greater unbalance of said bridge. f

In witness whereof, I hereunto subscribe my name this .22nd day of December, A. D.,

HORACE W. ULRICH.

a series

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