US2012573A - Translating apparatus - Google Patents

Description

Aug; 27, 1935. '1'. H. LONG I 2,012,573

Trumsm'rme APPARATUS Filed D66. l5, 1931 WITNESSES. INVENTOR llnu ' 772077205 H Long.

ATTORNEY Patented Aug. 2 7, 1935 PATENT OFFICE I mnsm'rmo msas'rus Thomas 1!. Long, Irwin; Pa a-ignor to Westingacturlng house Electric & Mann! corporation 0! Pennsylvania Company, a

Application December 15, 1931, Serial No. 581,152-

18 Claims. (01. 171-312) ations in the source of illumination whereby the My invention relates to translating apparatus and has particular relation to apparatus of the type incorporating electric discharge devices.

It is an object of my invention to provide, tor a translating system of the type incorporating a plurallectrode ,electric-discharge device, a

contrivan e for compensating for the variations 1 introduced in the response of the system by the effects of external physical disturbances.

Another object of my invention is to provide a translating system oi the type incorporating electric-discharge devices that shall have a uniform response regardless of the normally vitiating disturbances arising in the region wherein the system is disposed.

Still another object of my invention is to provide an energy translating system of the type incorporating electric-discharge devices that shall respond uniformly regardless of the normally vi tiating disturbances arising by reason of variations in the systems with which the apparatus is associated.

A further object of my invention is to provide a photo-sensitive relay oi the type incorporating an electroionic or an electronic-amplifying device that shall always haves predetermined response when influenced by radiations of predetermined characteristics'regardless oi the influence oi the physical properties of the environment'of therelay.

A still further object oi my invention is to provide a relay oi. the type incorporating a photosensitive trigger and an electrolonic or an electronic amplifying device for the trigger that shall have a predetermined response for predetermined illumination impinging on the trigger regardless of the variations in the elements associated with the relay and cooperating therewith.

A specific object oimy invention is to provide for an energy translating system, a contrivance for compensating for the eflfects of variations in photo-sensitive trigger oi! the relay is excited.

More concisely stated, it is an object o! my invention to provide an energytranslating systemoiatypethatshallbeparticuiarlyapplimble in situations where uniform response is required regardless of the characteristics oi the apparatus associated with the energy translating sys-' tem and of the environment of the translating system.

According to my invention, I provide an energy translating system incorporating a balanced network having input and output terminals. The balanced network' may be of the Wheatstone bridgetype and its arms should be of a character suitable for the purposes for which the network is utilized.

Normally, the input circuit is connected to two conjugate terminals of the network and the output circuit is connected to two other conjugate terminals. The input terminals are connected to a power supply source and when the network is incorporated in the translating system for the purpose of compensating ior the eilects oi variations in the power-supply source, that feeds the system, the input terminals of the network are connected to the power-supply source that feeds the translating system. Moreover, ii the net-' work is to provide compensation for variations in the power-supply source,the arms of the network that effect the necessary compensation are of a type responsive to voltage or current variations.

On the other hand, it the network'is to compensate tor the effects 01' ambient temperature put terminals thereof are connected preferably to an independent power-supply source'and the arms of the network that eii'ect compensation are of a character responsive to ambient temperature or humidity variations.

The output terminals of the network, whether it is utilized for compensating for voltage variations, temperature, humidity variations or other types of variations are coupled to the energy translating system in such manner as to provide the necessary compensation. It is understood, of course, that the coupling may be a direct connection, an electrostatic connection or an electromagnetic connection depending on the contingency of the situation. In many instances I have found in the practice of my invention thatan electromagnetic connection yields rather satisfactory results, since the electric discharge devices that are utilized in the translating systems of the type in which I am particularly interested respond to voltage variations rather than to current variations and by utilizing the proper transformers, I 1

can attain the necessary voltage without considerable loss of power in the network.

As has been suggested hereinabove, in the preferred practice of my invention, the network is commonlya Wheatstone bridge. When the network is utilized for compensating for variations in the output of the source supplying energy for the operation of the energy translating device, two opposite arms or the bridge are of a type having a substantial voltage coefficient of resistance. The other arms or the bridge are of a type having an inappreciable voltage coeiilcient of resistance.

It is of course understood that essentially only a difierence in the voltage coeflicients of resistance of the two sets of opposed arms is necessary. Hence one set may have a positive voltage coefli= cient of resistance and the other set a negative voltage coeiiicient of resistance, or one coefficient may be high while the other is low.

The output of the bridge is inductively coupled to one or more of the input circuits of the electric discharge devices incorporated in the en ergy translating system.

For predetermined output of the power sup ply system the networlr is so adjusted that it has zero output or possibly a predetermined output. A variation in output of the power system produces a variation in. the input of the network and consequent variation in output the .uEb'WGlk, The change is im, 'essecl suitably on oneor iriost of the control circuits of the electric devices. effect of the irr resscd s on the electric discharge devices is to compensate lor the effects of variations in the supply system on the output or. the elecl devices.

"lotecl normally the e power supply source is to s impressed between the princi le electric discharge device or e s stein, a d the con; 1 also, to ch nge e pots electrodes.

- n these changes co s corresconduit! changes iritrodu t... ww

- tive trigger, the source or illumination whereby the trigger is energized is normally excited from the power source whereby the translating system is energized. Conse uuently, a variation in the power source not only affects those potentials associated with the elec== trio discharge device and with the photo-sensi-= ive trigger, but also aflects the source of illumina= tion. By properly coupling a suitable network provided in accordance with my invention to energy translating system of this type, not only are the effects of Voltage variations on. the elec trio discharge devices compensated but the effects .an appreciable temperature coefiicient of resistance, while the other arms are constructed of a metal having substantially a zero temperature co efiicient of resistance. Specifically, the former set of arms might be iron, while the latter set of arms might be Advance. It is to be noted, moreover that in general, for purposes of temperature compensation, the groups of arms need only be of such character that they are each composed of metals that differ appreciably in the temperature coefiicient of resistance of the individual elements; that is to say, the set of arms having the lower temperature coefficient of re sistance need not necessarily have a zero temperature coefficient of resistance but may have a negative temperature coefiicient of resistance or even a low positive temperature coeificient of resistance.

The novel features that I consider characteristic or" my invention are set forth with particularity in the appended claims. The invention itself, howevenlooth as to its organization and its method of operation, together with additional objects and advantages thereof, will best be understood from following description of specific embodiments when in connection with the accompanying drawing, which:

Figure .l is diagrammatic View showing an embodiment of my invention, as it is implied to the compensation of variations in the source whereby power is supplied to energy translating system.

. is a diagrammatic v odiinvention as,

a diagrammatic vie vention as it ut" ii the ambient h ratus shown in l, primary ource (not sh one se s ill the l;

1, other cui'y pool ole .(l may tube without eatures o.. invention. the balances network 2i, u e on, are connected. across annals the power supply 3 :imary 5i and ate terminals 23 of the network variable resistance oi suitable charhave subual in m nitude. These resistors The other e ro voltage coefdcients.

- s nice at a given voltage.

desired that the network iii shall be balanced under normal conditions, the resistors should be of such character that, when conditions are normal, they have the same resistonce as resistors 29. Under such conditions, the resistances of. all sides of .the network will be identical.

It will be noted. that since tungsten and carbon have voltage coeflicients of resistance of opll utilized in posite sign that it may be desirable to use a network in which the opposite arms are respectively tungsten and carbon.

The output leads of the network are fed from two conjugate terminals 3| thereof'and are connected through the primaries 33 and 35 of a plurality. of transformers 51 and 35, the secondaries 4| and 43 of which are in turn connected between the control electrode 45 and the principal electrodes 1 and 5 of the electric discharge device II.

In the system of the type shown in Fig. l, the triggering device 41 is of thephoto-sensitive type and comprises an ordinary photo cell connected between the control electrode 45 of the tube I I and the secondary 45 of the compensating transformer 35. Potential is applied to the cell 41 from a potentiometer 49 that is, in turn, energized from a suitable section of windings 5| of the secondary 5 ofv the power supply transformer I. The lower tap 53 of the potentiometer 49 is connected to the cathode 9' of the electric discharge device ll through the impedance I1.

An impedance 55 of proper magnitude is also connected between the control electrode 45 and one terminal of the secondary 4| of the compensating transformer 51 that is disposed in the control circuit 35 associated with the anode 1 of the electric discharge device H.

The photo-sensitive device 41 is energized from a suitable source of illumination 51 that is supplied with power from'a section 55 of the secondary 5 of the power supply transformer i.

The network 2| is so adjusted that'for a predetermined output of the power source I, the resistances 29 are equal in magnitude to the resistances 21. The output of the network is theri zero and the electric discharge device I I is not effected thereby. When the output of the power source changes, the resistances of the lamp filament arms are changed and the balance of the bridge 2| is disturbed. In such a case a current having a polarity and a magnitude determined by the polarity and magnitude of the change in the power supply transformer I, flows through the primaries "and 35 of the compensating transformers 51 and 35, respectively, and corresponding potentials are impressed on the controlcircuits l5 and 5| of the" electric discharge device ll.

The character of the compensating voltage which need be supplied by the balanced network 2 I is dependent on the character of the photo-sensitive device 41 and of the electric-discharge device i I utilized in the system. If the electric-discharge device is of the grid-glow type, as is shown in Fig. 1, the variation in the output of the primary 5. since it effects a variation between the control electrode 45 and the principal electrodes 1 and l of the electric-discharge device II, has the effect of changing the breakdown characteristic of the system. The electromotive force impressed between the cathode 5 and the anode 1 of the electrio-discharge device of the grid-glow type is normally given such a factor of safety that it is not affected.

For example, if the output of the power source should be decreased, the potential between the cathode 5 and the anode 1 of the electric-discharge device would be decreased with substantially no effect. If at the same time a photosensitive device 41 of the high vacuum type is utilized in the system, the .current through the photosensitive device remains constant in spite of the decrease of electromotive force impressed thereon and consequently the drop of potential between the anode 1 and the control electrode 45 remains constant. As a result of this situation,

the potential drop between the cathode 5 and the control electrode 45 is decreased and less negative charge is required to be supplied by the cell 41 to the control electrode 45 of the electricdischarge device II to prevent the device from becoming energized than was required before the variation in the power output of the primary I took place. That is to say, the electric-discharge device now becomes energized for a lower flux of illumination impinging on the photo-sensitive trigger 41 than it did before the change took place.

In such a system the properties of the elements of the balanced network 21 are such that the electromotive force induced between the control electrode 45 and the anode 1 of the electric-discharge device II has the effect of raising the voltage of the control electrode 45 relative to the cathode 9 and of thus reverting the system to its original condition.

In the system of the type incorporating the high vacuum photo-sensitive cell, it will be noted that compensation of the system for the effects of the decrease of the illumination impinging on the photo-sensitive cell is not possible by the utilization of the lower compensating transformer 39. This transformer would have only the effect of raising the electromotive force impressed on the cell 41, and, since the cell, is of v the high vacuum type and is normally operated in its saturation region, the increase in the electromotive force applied to the cell would have no notable results. However, it is possible by properly designing the upper compensating. transformer 31, for example, or by utilizing two compensating transformers to affect the circuit 35 associated-with the control electrode 45 and the anode 1 to compensate for the variations in the source 51 that provides the illumination for exciting the photo-sensitive cell 41.

The application of my invention to a system incorporating a high vacuum photo-sensitive cell in which it is necessary to compensatefor variations in the illumination-produced by variations in the power source should be apparent to one' skilled in the art and need hardly be described herein. It need only be noted that if a decrease in the illumination takes place, for example, by-reason of a decrease in the output of the power source, fewer negative charges are supplied to the electric-discharge device ll than were supplied before the change took place and the potential of the control electrode 45 relative to the cathode 9 need, therefore, be decreased to compensate for the change. A corresponding situation arises when the power output of the power supply source is increased. When the photo-sensitive device 41 utilized in the system is of the gas filled type, since the effect of the variations in the output of the power supply system is to change the electromotive force impressed, across the photo-sensitive device, a consequent change in the current output of the photo-sensitive device takes place and the potential of the anode 1 relative to the control electrode 45 of the electric discharge device If is changed, as well as the potential of the cathode 5 relative to the control electrode. In such a case, it will be noted, that while the effects introduced by the compensating transformers must be of the same polarity as for the system incorporating the vacuum cell, the magnitude of the changes are somewhat different and as a result the compensating system must be designed 75 I of secondaries 85-and 81.,- 7 however, that the windings to suit the particular translating system with which it is to be utilized.

It is to be remembered also that while the potential of the control electrode 45 of the electrio-discharge device ll relative to the cathode 9, is changed by the compensating efiect, the potential of the anode 63, of the photo-sensitive device 51, is also changed relative to the cathode 65. The character of the compensating network 2i and of the transformers 31 and 39 associated therewith should preferably be of a type such that the anode 63 is raised to the same potential relative to the cathode 65 that it had before the change in the output in the power supply system took place. I may further say that in the system incorporating the gas filled photo-sensitive device, the compensation for variations in the source 51. of illumination may take place through the compensating transformer 39 associated with the circuit 6! of the energy translating network in which the photosensitive device 4! is connected. This situation arises by reason of the fact that the output current of a gas filled photo-sensitive device may be controlled by controlling the electromotive force impressed between its terminals.

It will be noted that while I have shown my invention as applied to a particular circuit, it is equally as well applicable to circuits ofother types. The circuit of the type shown in Figure 1, is commonly known as an inverse circuit; that is to say, it is a circuit in which the effect produced on the electric-discharge device is in inverse relation to the state of excitation of the photo-sensitive device. If the photo-sensitive device 41 is highly excited, the electric-discharge device II is deenergized, while, if the photosensitive device is in a state of low enough excitation, the electric-discharge device is energized.

The apparatus of the type shown in Fig. 2 incorporates a hot cathode electric-discharge 'device 61 in place of the cold cathode electric-discharge device ll utilized in apparatus of the type shown in Fig. 1. The electric-discharge device 61, shown in this view, may be of the gas filled or high vacuum type and comprises a cathode 69 heated from a suitable section II of the secondary 5 of the power supply transformer l, a control electrode 13 and an anode I5.

The output of the electric-discharge device 61 feeds through a meter 11 or a load of suitable character depending on the use to which the system is put. The photo-sensitive trigger 41 of the system is connected to an independent section of windings 19 of the secondary 5 of the power supply transformer I and the electromotive force impressed thereon is dependent only on the condition of the primary 3 of the transformer. The compensating system is of the same character as that shown in Fig. 1 with the exception that the compensating transformer 8| in the present instance has a single primary 83 and a plurality It is to be noted,

85 and 81 should be of such character as to provide the proper electromotive force for compensating purposes, and, by reason of the fact that the electromotive force impressed in the output of the compensating network is ordinarily rather small and the electromotive force required for compensation is ordinarily considerable, I have'found that the numberof turns of the secondaries 85 and 81 (and particularly of the secondary 85 whereby compensation for varying the of the secondariesv sensitivity of the cell 41 'is provided) should be The response of the system of the type described in Fig. 2 is the same as the response of the system of the type described. in Fig. 1. In analogy with the hereinabove set forth explanation, the two compensating secondaries 85 and 81 incorporated in the system may be utilized,

.respectively, for compensating for the effects .of variations in the illumination impinging on 4 shown in Fig. 2. As in apparatus of the type shown in Fig. 2, the output current of the electric discharge device 67 feeds through a meter 11 or a load of suitable character and is controlled by the response of a photo-sensitive device 41 to one or more sources of illumination (not shown). The power necessary for the operation of the system is provided by a suitable transformer 19 through a potentiometer 9| of proper character.

The compensating network 92 comprising a Wheatstone bridge, the pairs 93 and 95 of opposite arms of which are composed of metals between which there is a substantial difference in temperature coefficient of resistance, is fed from an independent power supply transformer 91 through a potentiometer 99 of proper character. As has been explained hereinabove, two arms 93 of the bridge may be of advance, which has substantially zero temperature coefficient of resistance, while the other two arms 95 of the bridge may be composed of iron which has a substantial temperature coeflicient of resistance.

The output of the netwo-rk'92 isfed into the input circuit of the electric-discharge device 81, one output lead IUI being connected to the control electrode 13 of the electric discharge device 61 and the, other output lead l0l being connected to the potentiometer 9| whereby power is supplied to the electric-discharge device. The balanced network 92 may be so adjusted that normally a predetermined biasing electromotive force is applied to the control electrode 13 of the electric-discharge device 61 through the output leads "ll of the network. A change in the ambient temperature produces a change in the resistance in the arms 95 of the bridge and a consequent shift in the potential of the output terminals I03 of the network 92. The shift in the potential is so impressed between the control electrode 13 and the cathode 69 of the electric-discharge device 61 that the necessary compensation for ambient temperature variations takes place.

It shouldbe kept in mind that the effects of ambient temperature variations on the electricgreater in number of turns than of the primary discharge device and on the photo-sensitive device utilized in translating systems have been rather aggravating in the past. The output of the electric-discharge device is apparently rather sensitive to temperature variations and thedevelopments which gave rise to the present inmethod taking care of the vitlating influences on the output 01 the electric-discharge device of the ambient temperature variations. By utilizing the balanced network as described herein-.

above, I have found that the deleterious effects of temperature variations are substantially eliminated and that the system has uniform response regardless ct temperature variations in its neighborhood. V

While I have'found that for the practical purposes to which I have applied translating apparatus incorporating electric discharge devices, the elects introduced by variations of other types than temperature. variations and voltage variations are substantially negligible, it is highly con-' ceivable that in certain types of apparatus the eifects of these variations might become of some importance. It will be observed that my inven-- tlon is applicable to compensation of ambient humidity variations and changes of other types produced in the environment of the translating apparatus. Systems-in which other variations in the environment of the translating apparatus than temperature variations or variations in the power supplied for energizing the translating system are compensated, are therefore, equivalents which lie within the scope of my invention.

Although I have shown and described certain specific embodiments of my invention, I am fully aware that many modifications thereof are pose slble. My invention, therefore, is not to here-- strictedexcept insofar asis necessitated by the priorartandbythespiritoftheappendedclaims.

I claim as my invention:

1. In a translating systemof the type including an electric discharge device having input and output terminals, power supply means connected to said output terminals, and means responsive to ambient temperature variations coupled to said input terminals of said electric discharge device to compensate. for the effects of ambient 7 temperature variations thereon.

2. In a translating system of the type including an electric discharge device incorporating a control electrode and a plurality of principal electrodes, a network, including a plurality of symmetrically related arms having a substantial temperature coeilicient of resistance and a 'plurality of symmetrically related arms having a small temperature coeiiicient of resistance, said network having input and output terminals, power supply means connected to said input terminals, and means for coupling said output tertrlcdischargedevicirtdcompensatefortheeb" fects of ambient temperature variations thereon.

4. The combinationwith anelectric discharge device of a network having input and output terminals, power supply means coupled to said input terminals, means to respond to ambient temperature variations to vary the voltage impressed acroassaidoutputterminalsandmeansforcouplingsaidelectricdbchsrgedevicetosaidoutput aora's'rs terminals to compensate for the eifect of ambient temperature variations thereon.

5. The combination with a network of the type having input and output terminals including a plurality of groups of symmetrically related arms, 6 the temperature coemcients of resistance of the elements of one group being substantially different from those of elements of another group, and means for impressing an electromotive force across said input terminals, of an electric disl0 charge device and means for coupling said output terminals to said electric discharge device to compensate for the effect of ambient temperature variations thereon.

6. A translating system comprising an electric 1 I discharge device having a controlelectrode and a plurality of principal electrodes, circuits associated with said principal electrodes and with said control electrode, power supply means for energizing said electric discharge device coupled 2 to the circuits associated with the electrodes of said device, a circuit having input and output terminals and incorporating a plurality of symmetrically related conductive arms, certain of said arms having an inappreciable voltage coemcient of resistance and certain others of said arms having an appreciable voltage coeflicient of resistance, means for coupling said input terminalsto said power-supply means and means for so coupling said output terminals to at least one of the circuits associated with said control electrode and said principal electrodes of said electric discharge device as to compensate for the effects of variations in the voltage oi. said power supply means on the response of said electric discharge device.

7'. A translating system comprising an electric discharge device having a control electrode and a plurality of principal electrodes, a circuit associated with said p ipal electrodes, a plural- 40 ity of circuits associa with said control electrode and'said principal electrodes, photosensitive means, of the type having a saturation characteristic coupled to one of the circuits associated with said control electrode and one of said principal electrodes, power supply means coupled to the circuit associated with said principal electrodes, the electromotive force supplied to the circuit coupled to said photosensitive means being of such magnitude that said photosensitive means is normally operated in its saturation region, a circuit having output terminals and having input terminals coupled to said power supply means, said circuit incorporating means.

responsive to theelectromotive force impressed thereon and means for coupling the output terminals of said balanced circuit to the circuit coupled to said photosensitive device to vary the electromotive force impressed on said lastnamed circuit and thus to compensate for the 60 eflects, on the condition of said circuit associated with the principal electrodes of said electric discharge device, of variations in said power supplyvoltage.

a 8. A translating system comprising an electric as discharge device having an output circuit and a plurality of input circuits, power supply means coupled to said output circuit to apply an electromotive force to said output circuit and said input circuits, photosensitive means connected in one of said input circuits, said photosensitive means being of a type having a response that is a function of the electromotive force impressed thereon, and means coupled to another of said input circuits and to said power supply means 76 for compensating for the effects on said output circuit of variations in said power supply voltage.

9. A translating system comprising an electricdischarge device having a control electrode and a plurality of principal electrodes, means for impressing potentials between said control electrode and said principal electrodes and between said principal electrodes, a network including a plurality of arms having substantially difierent coefiicients of resistance, said network having input and output terminals embracing different arms thereof, power-supply means connected to said input terminals and means for so coupling said output terminals between the control electrode and the principal electrodes of said electric discharge device that variations in the operating characteristics of said electric discharge device that are produced by conditions tending to produce a change in the resistances of certain of said arms are neutralized by the additional potentials impressed between said control electrodes and said principal electrodes from said network.

10. A translating system comprising an electric discharge device having a control electrode and a plurality of principal electrodes, means for impressing potentials between said control electrode and said principal electrodes and between said principal electrodes, a network including a plu= rality of arms having substantially different voltage coeflicients of resistance, said network hav-= ing input and output terminals embracing different arms thereof, power-supply means connected to said output terminals and means for so coupling said output terminals between the control electrode and the principal electrodes of said electric discharge device that variations in the operating characteristics of said electric discharge that are introduced by variations in the potential supplied by said means for impressing potentials between the electrodes of said electric discharge device are neutralized by the additional potentials impressed between said control electrodes and said principal electrodes from said network.

11. A translating system comprising an electrical discharge device having a cathode, an anode and a control electrode, a voltage source connected to cause current flow between said anode and cathode, a network comprisinga bridge cir cuit, the opposite sides of said bridge being resistances of similar temperature coeificients but the temperature coeflicients of adjacent sides of said bridge being dissimilar to each other, connections from a pair of diagonally opposite junctions of said bridge circuit to said voltage source and connections from the other pair of diagonally opposite corners of said bridge to impress a voltage tending tomake said control electrode less positive relative to said cathode whenever said voltage source makes said anode more positive relative to said cathode.

12. A translating system comprising an electric discharge device having a control electrode and a plurality oi principal electrodes; a circuit associated with said principal electrodes, a plurality of circuits associated with said control elec-- trode and said principal electrodes, photosensitive means, of the type having a saturation characteristic coupled to one of the circuits associated with said controlelectrode and one of said principal electrodes, power supply means coupled to the circuit associated with said electric discharge device, the resultant electromotive force supplied to the circuit coupled to said photosensitive means being of such magnitude that said photosensitive means is normally operated in its saturation region, means to be energized from said power supply means for energizing said photosensitive device, a network having output terminals and input terminals coupled to said power supply means, said network incorporating means responsive to variation in the electromotive force impressed thereon, and means for coupling the output terminals of said network to the circuit coupled to said photosensitive device to vary the electromotive force impressed on said last-named circuit in such a sense as to compensate for the effects, on the condition of said circuit associated with the principal electrodes of said electric discharge device and on said energizing means for said photosensitive device, of variations in said power supply voltage.

13. A translating system comprising an electric discharge device having a control electrode and a plurality of principal electrodes, circuits associated with said principal electrodes and with said control electrode said principal electrodes, photosensitive means, of the type having a saturation characteristic, coupled to a circuit associated with said control electrode and one of said principal electrodes, power supply means coupled to a circuit associated with said principal electrodes, the electromotive force supplied to the circuit coupled to said photosensitive means being of such magnitude that said photosensitive means is normally operated in its saturation region, a circuit having output terminals and having input terminals coupled to said power supply means, said circuit incorporating means responsive to the electromotive force impressed thereon and means for coupling the output terminals of said circuit to the circuit coupled to said photosensitive device to vary the electromotive force impressed on said last-named circuit in such a sense as to neutralize the efl'ects, on the condition of said circuit associated with the principal electrodes of said electric discharge device, of variations in said power supply voltage.

14. A translating system comprising an electric discharge device having a control electrode and a plurality of principal electrodes, circuits associated with said principal electrodes and with said control electrode and said principal elec-- trodes, photosensitive means coupled to a circuit associated with said control electrode and one or said principal electrodes, power supply means coupled to circuit associated with 'said principal electrodes a circuit having output terminals and having input terminals coupled to said power supply means, said circuit incorporating means responsive to the electromotive force impressed thereon and means for coupling the output terminals of said circuit to the circuit coupled to said photosensitive device to vary the electromotive force impressed on said last-named circuit in such a sense as to neutralize the eifects,

on the condition of said circuit associated with I the principal electrodes of said electric discharge device, of variations in. said power supply voltage.

15. The combination with an electric discharge device of a network having input and output terminals, power supply'means coupled to said input device and a photosensitive devicetor controlling said electric discharge device of a network having input and output terminals, power supply I means coupled to said input terminals, means to respond to ambient temperature variations to vary the voltage impressed across said output terminals and means for coupling said electric discharge device to said output terminals to com-- pensate for the efiect of ambient temperature 10 variations thereon.

20 said control electrode and said principal electrodes, photosensitive means coupled to a circuit associated with said control electrode and one of said principal electrodes, power supply means coupled to a circuit associated with said principal electrodes, a source of radiant energy {or exciting said photo-sensitive device, said source being energized from said power supply means, a circuit having output terminals and having input terminals coupled to said power supply means, said circuit incorporating means responsive to the electromotive force impressed thereon and means for coupling the output terminals of said circuit to the circuit coupled to said photosensitive device to vary the electromotive force impressed on said last-named circuit in such a sense as to neutralize the eflects, on the condition of said circuit associated with the principal electrodes of said electric discharge device, of variations in said power supply voltage.

' THOMAS H. LONG.

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