US2607912A

US2607912A - Voltage regulator

Info

Publication number: US2607912A
Application number: US245538A
Authority: US
Inventors: Adolph O Bunblasky; Allen K Brown
Original assignee: Sorensen & Co Inc
Current assignee: Sorensen & Co Inc; Sorensen & Company Inc
Priority date: 1951-09-07
Filing date: 1951-09-07
Publication date: 1952-08-19
Anticipated expiration: 1969-08-19

Description

Aug: 19, 1952 A. O. BUNBLASKY ET AL VOLTAGE REGULATOR Filed Sept. '7. 1951 ATTORNEY Patented Aug. 19, 1952 VOLTAGE REGULATOR Adolph 0. Bunblasky, New Canaan, and Allen K.

Brown, Stamford, Conn., assignors to Sorensen & Company, Inc., Stamford, Conn., acorpora tion of Connecticut Application September 7, 1951, Serial No. 245,538

13 Claims.

rThis invention `relates to new Yand useful 'improvements in voltage regulators and Vhas particular relation to a regulator for controlling the voltage from an alternating'current power sur ply so that said voltage remains virtually constant over a relatively wide rangel of ypredeterminable voltages.

In general, the present .regulator includes a bridge type network vhaving `a diode vacuum tube forming one of the arms of the bridge. The iilament of the diode is connected across the output of the voltage'regulator whereby the temperature of the :filament changes in response to changes in the output volta-ge; This temperature change then results in a change in the plate resistance of the diode ,and a subsequent imbalance of the bridgecircuit.. The output ci the bridge is then fed through a filter network in order to reduce any component ripple -voltage and is used to control thev output from the first stage of a cascaded amplifier. The output from the first stage is fed through a ,second filter network into the second. stage.

` The output Afrom the cascaded amplier is then fed through anotherfilter circuit lwhich nulliiies any tendency for the circuit to hunt and is then appliedto the icontrolgrid of another vacuum tube. vThe vplate current ofthis latter tube is fed through the direct current winding or" a saturable core reactor in order to control the impedance of Vthealternating fcurrent Winding. As this Winding .is in series -iwith a 4lead common to the input'circuit'and Voutput circuit of the regulator, the -voltageis varied in accordance with the impedance of thealternating current winding. Thus, the output ofthe regulator approximately i .01% against variations ldue v from any of the vacuum tubesl include'din the circuit fail, the `output voltage would tend to drop rather than rise therebyprotecting any Iter-minal 23.

equipment fed lfrom the output `from' being damaged by excessive voltage.

Another object is to provide a highly stable voltage regulator meeting the above objects and also providing a virtually distortionlessalternating current output.

Still another object is to provide a highly stable voltage regulator adapted to start even under large loads.

The above and other objects of the'invention will become apparent from a consideration oi the following detailed description taken in con` nection with the accompanying drawing wherein a satisfactory embodimentof the invention is shown. However, it vis to vbe understood that the invention is not limited to the details disclosed but includes all such variationsand Amodiiications as fall within the spirit of the .in've'n-rv tion and the scope of the appended claims;

In the drawing 'the `iigure represents a schematic diagram'oone embodiment of the ,invention.

Referringin detailftothefdrawing, an alternating currentinput is applied to `a pair o'finput terminals Ii] and `II and is thence fed through a pair of contacts I2 and I3 of'onoi switch I4. The side of -the'line connected to the yterminal IU through the switch vContact I2 is con-` nected directly to atapVV I5on an auto-transformer Ithrough -a lead- I2a. The other "sideof theline, i.,e., that connected tothe terminal II through the switch contact I3, is fed by aconnection I'I through .the alternating current windings vI8 and I9 0i a saturable ycore'ireactor 2.6, which also has a direct currentvwindin'g r2I, to a terminal 22 of the'.auto'transiormer Iii. Thus, the alternating curre'rit windings IS and i9 lare in series with lthe connection Il forming part of a feed line to the auto-transformer `I G;

The alternating` current output'is developed across the youter ends of the auto-transformer i6 and appearsacross thefterniinal 22 and a The-terminal V23 lis `carried by ra connection 24 through a `thermal-overload switch 2-5-to an outputiterminal 26. Another output-terminal 2'I is'connectedfdirectly tothe connection I'I'by-means of aleadB.'

Inorder to filter outany third harmonic distortion whichmight be otherwise present at lthe output,=a lnetwork comprising a pair of capacitors 29 and l3B andan inductance 32 is.provided. The capacitor-staand 3a are connected' in parallel and this combination is then connected in series with the inductance 32 across the 'output' lines formed bythe connections `I'I and 24.' 4In order to lter `out ariy'iiithv harmonic distortion, a

aeozoia filter comprising a series combination of a capacitance 33 and an inductance 34 is also connected across the connections 25 and I1. An inductance 35 is placed across the terminals 25 and 21 in order to provide an inductive load so as to make the regulator capable of handling loads with a capacitive power factor.

A transformer 36 is associated with the control circuit presently to be described in detail. The primary 31 of the transformer 38 is connected directly across the output terminals 26 and 21. An end terminal 38 is connected through a fuse 39 to the output terminal 25. Another end terminal 48 is directly connected by a lead comprising the

sections

4I, 42, 43, 44 and 45 to the other output terminal 21.

A secondary 45 of the transformer 35- is connected directly across the

plates

41 and 48 of a rectifier tube 48. Another secondary I is connected across the filament 52 of the rectifier tube 49 to provide heating current therefor. A direct current voltage is thus developed across a terminal 53 associated with the filament 52 and a center-tap 54 on the secondary 45. This voltage has, of course, a decided ripple which is effectively reduced by a capacitor 55 and a resistance 55 connected across the terminal 53 and the center-tap 54. Resistance 55 also serves as a voltage divider to provide voltage of a proper value for the screen grid 51 of a vacuum tube 58.

The vacuum tube 58 is associated with the control circuit hereinafter fully described. Briefly, however, the plate current from the vacuum tube 58 is fed through the direct current winding 2! of the saturable core reactor 28 to control the impedance of vits alternating current windings I8 and I9.

Plate 59 of the vacuum tube 58 is connected through a load resistance 60 to the terminal 53 of the rectifier 48. The direct current Winding '2l is connected in parallel with the load resistance 55. The negative terminal of the rectified supply, as represented by the terminal 54, is connected directly to a cathode 52 of the vacuum tube 58. A bleeder resistance 6I is provided between the plate 59 and the screen grid 51.

former 55 is connected between the terminals 23 and I5 of the auto-transformer I6. The secondary winding 65 in series with the secondary Winding 54 acts as a booster which enables the regulator to start even under large loads.

By way of example, assuming a load of 1000 volt-amperes and a voltage input to the regulator of only 95 volts, if the unit is then turned on by closing the on-off switch I4, the voltage across the secondary 64 of the transformer 35 may be so low as to prevent the filament 63 from heating. By providing the secondary winding 55 of the booster transformer 56, the voltage across the filaments will be sufficient to allow the vacuum tube 58 to heat up and thereby make the control circuit operative. Once the control circuit operates, the normal filament voltage is developed across the filament 63.

The principle of booster transformer 66 is that the difference between the input and the output voltage is impressed on the primary of this trans- 4 former. When the control circuit is not operating, this difference is relatively large and thus applies a correspondingly large boost to filament 53. Once the control circuit operates, the difference becomes small and a very negligible, if any, boost is applied to filament 63.

A Wheatstone type bridge circuit comprising arms formed by resistances 10,' 1I, and 12 and a diode vacuum tube 13 is provided in order to detect changes in the voltage across the output terminals 25 and 21. The diode vacuum tube 13 is preferably a special diode, as fully described in l a copending application of Helterline et al. en-

titled Filament Failure Device for Electronic Tubes filed April 1, 1949, under Serial Number 84,806. This diode has the characteristic that shouldthe tube fail for any reason, the filament is shorted to the plate. This is illustrated schematically in the figure by an arm 14 connected to a plate 15 of the diode 13, said connection being within the envelope of said diode. Upon failure of the tube, due to its filament 16 burning out, arm' 14 comes in contact with the filament 16 of the diode 13, thereby shorting said plate 15 to the filament 16.

Although a conventional diode may be used in place of the special diode described, it is preferable to use such a special diode as a safety precaution. By way of example, upon failure of thespecial diode 13, the short circuiting of the plate and filament results in a decrease in the output voltage across the terminals 25 and 21. This is of importance if equipment sensitive to high voltages is being supplied by the regulated output. If a conventional diode were used, the output voltage would tend to`rise with possible silibsequent damage to the equipment being supp ied.

One side of the filament 16 is connected by a lead 11 through a pair of serially connected dropping resistances 18 and 19, thence by a lead 8| to a movable pole 82 of a single pole double throw switch 83. A contact 84 of the switch 83 is connected to a variable resistance 85. The other contact isconnected to a second variable resistance 81 and the two ends of the variable resistances 85 and 81 are connected to a lead 88. Thus, when the movable pole 82 is against contact 84, leads 8I and 88 are connected together through the variable resistance 85. In a similar manner, when the movable pole 82 is against contact 86, the leads 8| and 88 are connected together through the variable resistance 81. By means of the switch 83 and the variable resistances 85 and 81, the filament current may be varied in order to adapt the circuit for operation over a wide range of desired output voltages.

Lead 88 is connected to the lead 4I and thence to the terminal 48 associated with the primary 31 of the transformer 36. The other side of the filament 16 is connected through a lead 98 thence by a lead QI to the terminal 38 of the primary Winding 31. As the voltage across the terminals 38 and 40 is the same as that across the outputs 26 and 21, it is evident that the filament 16 is likewise across the outputs and its temperature and hence emission will vary with changes 'azionare the output terminal 21. y The terrn'inaffljicon- Iiooted through thetub .socketfoithedodo 13 so that in theevent the diode 1 3 is vren 1oyed o ne side ofl the linev to the'primaryjof the trans- .former 92` and the primary 31 of the transformer 3|.`is automatically opened.

. This' results 4in Vthe .power supply includingthe :diode 49 being deenergizedthus rQmQYIlg plate voltage from the'yacuumjtube 5 8... 'Iherexfcre. the current' through the direct current winding 21 of the saturable core reactor 20 `is reduced tozero and the impedanceof the 'alternating current portions 18 and I9 increases to reduce' the voltage acrossthe'output terminals 26 and 21. As mentionedin connectiomwith the'description of the diode 13,'this is an important. safety feature .for protecting .any sensitivexequipment fed from the output terminals"26"an d21..

A secondary winding102 of the .transformer 92 .provides a Voltage supply for the bridge circuit.

The alternating current developed across the secondary 1 02Lis rectified by a suitablefrectier l|113 which may be of the selenium, copper voxide or, in fact, of .any convenient type. Qne side ofthe 'rectifierf103is connectedtoa terminal 104er the secondary102 and the other side is connected throughfa resistance |05 1and a resistance 1135 .to aninputterminal 101 Qf the bridge circuit.

.The other terminal 1.08 of thesecondarywinding |02 is ,connected drectly to another input terminall of the'bridge circuit. A capacitor 116 is connected from the terminal |08 to the junctionof theresistances l|115 and |0 6.

The capacitance, in conjunctij on with the resistance A1 (15, servesas a filter network Ato smooth out thoroctihor, ripple ,and .the .resistance 106 ...serves aspart-oiavo1taee divider .to predotormiho the voltage acrossthe bridge input terminals |01 and 10.9. Neontubes, 1 1 1 112, 113) and |14 are lconnected across the inputterrninals |01 and 10Q ,.to..f urther .stabilize theroltoeo applied to the bridge, As the primary 9 3 of the transformer 92 .is ...connected-V ooross .the .regulated output termi- .,nels'ahd ,2.1. the .output of .thorootor H13 iS quite stable but, by providingthe neon tubesstill v further voltage stability is achieved, A constant input voltage to the bridge circuit Ainsures that the ontput of the bridge `will yary onlyq in Aaccordance v with changes in the impedance of the vacuum tubo 1 3.

An increase in the'voltagehwillMcausethe'nlanient 1 6 of the diode 13 to increaseintempera- .turewith a resulting increase inemissiornwThis causes the impedance of the diode 13 to decrease and aresultingunbalance' in the bridge. This .uhbalehoo .further ,results .ih o choose. in. the yoltageappearing across a pairof bridge output terminals |5 and |13 causing theterminal |15 .to become more negative with respect to the terminal-A 1 16.

r The output yoltagedeveloped theoutput terminals |15 and `11|; of the bridge circuit is applied to a filter network I 1"!A connected'between acontrol grid 1 i8 anda cathode 19 of a dual vacuun1tub e 120. The filter network |11 comprises two'serially connected4 capacitors 23 and .124 Aconnected in parallel with a resistance |25. The resistance is connected between the bridge O utputterminal |15 and the control grid 1 18. A resistance |26 is connected between the j''nction of the serially connected capacitors |23 and |24' and the cathode 19 of the vacuum tube l greatly attenuate any 120 cycle ripple appearing tutti@ for the bridge. "The izo cycle 'ripple' is introduced in the`- ley""virtueA of the` 'full Wave powersupply 'comprising' the transformer' 3B and the dualftriode yacuumftbelil. An addi- "tota no' colocataires@ throated the Circuit due L to the ytlfierrnal effectI of the diode filament. By attenuati athis ripple, the voltage 10 cathode ,l le .is olist hiitodloot @destron- .ago oxoootfore Spoil@ oyclerpplemtroduced plenair Q ftiie' vacum sup comprising uiegnd direct current; '.arhpliher- Theplato .Supply Yoltserfothe plato. T. ,is

developed .from as oohdarmwhdhg 1.28..,of. the transformer. 212-., @he terminale? the. Seconery 12B is Connectodthroueha oonrohtiohol rootihor element ,1;29 thencey ,throlehe .resistance 130.110 the platey |21, Theother terminalofthe secondary winding 12.8 'is connected; through .ai ltor Acaracter |31 'and thoroeto. tho plate. |21g f 'A p airof serially-connected resistances13 2 and |33 are connected as ableeder across the capacitor A second'filter network 135,. similar in arrangement tothe filternetworl; |11,;i s connected between a control grid |36 and a cathode 1 31-of the other half of the'dual-triode vacuum tube 12|?. The network |35 co mprises two serially connected capacitors 138" and |39 connected inparallel with a resistance "14 ,Thel resistance 14|is connected between the cathode 1 19 of y'the' rst half ofthe dual-triode and the control grid 1330i the second half. "Ihus,A 'thev output Vfrom the-first'half of the dual-triode v'121) istaken from thecathode 119. A resistance |42 is connected'between'the junction ofthe capacitors |38' and "1 39and the cathode |31 of Vacuum tube |20.

' The function of filter '|35 differs from that of the lter |11 in that'lter |35 is adapted 'to reject or greatly attenuate 60 rcycleripple.rather than 120 cycle ripple. lThis ripple originates from the power supply providingvoltage to the bridge input terminals 101'and |09. This 60 cycle ripple is amplied by the first half ofthe dualetriode vacuumtube 1'20"so"as to be" at a higherlevel than the direct lcurrentcomponenth It therefore mustbe' attenuated vbefore it is applied to the control grid 136'of the -second half of the tube in order that the"seclo'nd half 'of the tube may also act asaldirec'current amplifier. 4 A- plate |43 of the" second half of the duali t'riode is connectedto a source-of potential by a lead 144 to the' bleederr`esistance""56 connected across the output 'ofthe power'supply'fornied kby the transformer 3 6 andthe duo-diode 09. The filaments H of the' Vacuum t'ubef |20 arespplied directly from a'secondary'lltoffthetransformefw- The end of the resistance 1'41j'connected`to the cathode` 1"1 El is also connected through* aresistance 1l l1""to the secondary' winding 128' of Vthe which is connectedto the 'cathode '131jis vconnected 'alsoto the junction' between the bleeder resistances 1321and'133rf'h potential of the cathode 1311's then at a iugiiefpositive potential than the control grid |36 and4 the tubeisy biased. As it is desirable'to furnish a negative'bias Voltage for arcont'rolgrid1 34vfof-theyacuum tube 5 8, apower supply to provide saidbiasing Vvolti eso provided said .powersupply Q Olhhrisos a secondary winding 158 of the transformer 92, one

It is thus seen that the input to the first half of the vacuum tube |20 isapplied between the grid ||8 and the cathode H3. The-output from the cathode ||9 is then applied to the filter |35 to eliminate 60 cycle ripple and thence impressed between the control grid-'|36 and the cathode |31. This causes the Voltage at the cathode |31 to change resulting in a change in the bias on the grid |34 of the vacuum tube 58. By Way of example, assume the output voltage tends tol rise. This causes the filament 16 of diode 13 to increase in temperature with a resulting increase in emission causing a decrease in the impedance of the diode and a resulting unbalance in the bridge. This unbalance is manifested as a decrease in the potential of the terminal with respect to the-terminal ||6.

As terminal l5 is connected to the grid I8 of vacuum tube and the terminal ||6 is connected to the cathode, the grid ||8 is made more negative with respect to the cathode causing the current in theY tubeto decrease. As the cathode follows the grid, its potential likewise drops. Now, as the cathode ||9 is also connected through the resistance |4| to the control grid |36 of the other half of the tube |20, the potential of the grid |36 will .also drop as will the potential of the cathode |31. As the cathode |31 is connected by a lead |48 through a resistance |43 to the control grid |34 of the Vacuum tube 58, the potential of the control grid |34 will also decrease.

Therefore, the plate current through the tube 58 is decreased with a resultant decrease in the current through the direct current winding 2| of the saturable core reactor 20. This causes an increase in the impedance in the alternating current coils I8 and |9 and a concomitant decrease in the magnitude of the alternating cur- E rent voltagevoutput. A decrease in the output voltage would cause the same cycle of events but in the reverse direction.

A filter network |5| similar in arrangement to the filter networks ||1 and |35 is connected between the grid |34 and the cathode 62 of the vacuum tube 58. The network |5| comprises tWo serially connected capacitors |52 and |53 connected in parallel with the resistance |49. A resistance |54 is connected with the junction of the capacitors |52 and |53 and the cathode 62. This latter connection is made by a lead |55. Thus, the output Voltage from the cathode |31 of the tube |20 is applied through the filter |5| to the grid-cathode circuit of the vacuum tube 53. This filter prevents hunting which occurs when the control circuit overshoots. For example, if the output voltage rises, the control circuit may over-correct and this cycle will continue at a comparatively low frequency, the value of which will depend upon the time constants in the Various resistance capacitor combinations in the control circuit. A vfrequency of approximately 2.5 cycles is typical and hence if a filter capable of n rejecting this frequency is placed across the gridcathode circuit of the vacuum tube, hunting will not take place.

Another anti-hunting feature is provided by connecting a pair of capacitors |56 and |51 across the primary 31 of the transformer 36. The cathode 62 of the vacuum tube 58 is connected to the junction of the capacitors |56 and |51. When the circuit tends to overshoot and the grid |34 is being actuated in one direction, an alternating current voltage is applied to the cathode 62 yso as to counteract the overshoot of the grid voltage.

Having thus set forth the nature of our invention, what we claim is:

l. A highly accurate electronic voltage regulator adapted to regulate the magnitude of `an alternating current voltage between predetermined limits, said regulator including an input circuit, transformer means having a firstportion associated `with said input circuit, an output circuit connected with a second portion of said transformer means, a saturable core reactor having an alternating current portion and a direct current portion, means for alteringv the voltage across said transformer means and thereby the output circuit by varying the impedance of said alternating current portion, a bridge circuit having a diode vacuum tube forming one of the arms thereof the filament of said diode being connected across said output circuit whereby a variation in the outputvoltage varies the temperature of said filament to thereby imbalance said bridge, a direct current amplier, filter means associated with said direct'current amplifier, means for applying the output ofsaid bridge circuit through said filter means to said direct current amplifier whereby said filter means is adapted to reject unwanted alternating current ripple which may be present in the output from said bridge circuit, vacuum tube means, means for applying the output from Vsaid direct current amplifier to said vacuum Ytube means to control the platecurrent thereof,`and means for applying said plate current to the direct current portion of said saturable core reactor to r control the impedance of said alternating current portion and to thereby maintainy the Voltage of y said output circuit within said predetermined limits. I

2. A highly accurate electronic voltage regulator adapted to regulate the magnitude of lan alternating current voltage between predetermined limits, said `regulator including an input circuit having the' primary of an auto-transformer connected thereto, an output circuit associated Awith the secondary of said autotransfonmer, a saturable core reactor having an alternating current portion anda direct current portion, means for altering the voltagegacross said transformer means and thereby the output circuit by varying the impedance of said alternating current portion, a bridgecircuit having a diode vacuum tube forming one of the arms thereof, the filament of said diode being connected across said output circuit whereby a variation in the output voltageyaries the temperature of said filament to thereby unbalance said bridge, a direct current amplifier, filter means associated with said'direct current amtransformer means; asaturable core reactor having analterna'ting current portion anda dirctcurrentportion, 4means for altering the volt-v ageacross Vsaid transformer meansl and thereby the output circuit by' Varying the' impedance of said alternating current portionfa bridge `circuit l havingv 'a'diode-vacuumtube Vforming one of the arnis thereof the-'filament 'cfg said diode being cbnne'ctediacross"said output circuit whereby a variation irr'the 'output' lvoltage varies the temperaturepf saldi filament' to "thereby"imbalance saidbridge, 'a direct''current amplifier, iilter means associated with saidz direct, current amplifer; rneans'ifor applyingthe output ofv said bridge circuit' through `"said lternieans to-said direct current amplier'ivhereby said filter means 'is adapted to "reject unwanted alternating current ripple' which 'maybe present ing' the output from saidibrid'ge" circuit, vacuurntubemeans having at least a platefafcontrol: grida-nd4 a cathode, an anti-hunting"means,"v said means comprising a filter network between said control grid and said cathode'f i said; iilter -'network being' adapted to rejectv 'the' "frequency "at "which "said, regulator would tend to huntf'rneans for applying the output "from "said, directf current; Vampliiier through said anti-hunting means` to the control gridl of said:y vacuum'tub'e means Vto control the plate current" th'ereofff-and'nneans; for applying said platecurrentrto therdirectl current portion of saidl"saturable core reactor tol control 'the impedance'of said alternating current portion and to'"'thereby maintainthej voltage of,X said output circuit 'withi'n"'said' predetermined limits.

41A highlyA accurate' 4electronic voltage regulator adapted touegulatethe' magnitude of an alternating `current voltage between predeterminedflirni'ts, saidregulat'or including an input circuit, transformer means having aiirstpcrtion associatedwith 's'aid input circuit', an output cirn cuitconrecte'd:with'a secondportion of said transformer means, a saturable core reactor 'having an alternatingrurrent portio'rrand a'direct current portionjmeans" for' laltering the voltage lacross said transformer means and thereby the output circuit byV` varying Ithe "impedance "of said altermating current portion', a 'bridge circuit `having a diode-'vacuum tub'ewforming'one ofthe arms thereof the filament of'said diode being connected across said outputcircuit 'whereby' 'al variation in the output voltage varies-thetemperature of'said filament "to th'erebyunbalance' rsaid ybridge; a double "stage direct'lcurrent amplier having a rst Vacuum tube means and a 's'econdvacuum tube means; each of"said"vacuum`"tube'means having" at reastaj plate, acathode andA control Aa irstfillterv means connected between 'the id and cathode'of said lirst Vacuum tube means, cond iilter"'rne'z'tns"c o'nr'iecteo'ly the'grid and "cathode 0f' Seid. Second Yaiuuel tube means,

bh 0f Said'futr fris, beins'adapted to attenuate separately alternating current ripple components superimposed on the output from said bridge circuit, means for talringthe output from the cathode of said rstvacuumtu'be means and applying it through said second ii'lter rneansto the controlr gridvof saidsecond vacuum 'tube means, athird Vacuum tubemeans'havingat least a plate, a cathode anda control grid, an anti-hunting means, said means comprising a lter network between said last mentioned controlgrid andcathode, saidfilter network being adapted to reject thefrequency-atrwhich Ysaid regulator would -tend to hunt; means for taking the output from the Acathode of Vsaidv second vacuum tube means through f said anti-hunting means to the control-'grid vof saidthird Vacuum tube means to control the'plate current thereof, and means for applying saidplate currentto the direct current portion of said saturable core reactor yto controlV the impedance of said alternatngzcurrent portions' and to thereby maintain the voltage of said youtputfcircuit Within saidl predetermined'limits.vv v I f f v- 5. Ahighly accurate electronic voltage regulator adapted to regulate -fthemagnitude ofv an alternating' current' voltage -betweenpredetermined limitssaid regulatorV including an input circuit, transformer means-having a rst portion associated with said input circuit, an output 'circuit connected vwith asecondf portion offsaid transformer means, a saturablecore reactor having anl alternating currentY portion anda direct current portion; means for altering the voltage across said transformer means andtherebythe output circuit by Av'aryingthe impedanceof said alternating current portion, al bridge circuit having a diode 'vacuum tube forming one ofthe arms thereof the nlament of said diode being connected across said output circuit v'fherebyia Variation in the output voltage Varies" the temperature of'said filament to 'thereby' -unbalance said bridge, a double stage direct "current amplier having a r'styacuum' tube `-means"'and a second 'vacuum tube means, each of "saidfvacuumttube Vmeans having at least-"a plate, v` a' 'cathode andi a control grid, a first iilter means :connected between the grid and cathode ofsaidrs'tvacuum tube means, a second lter'means' connectedbetween'thegrid and cathode of said second'vacuumtube means, each of said filter meaxisbeing'adaptedto attenu'ate separately'alt'ernating "current "ripple components"superimposedv otheV Voutput from said bridge'circuitfmeansfor takingthe output from the cathode of said 'first' vacuum tube means and applying it through'saidsecond filter"means to the control grid" of said "secondva'cuum tube means, a third Vacuum"tube'mearls` having'at least a plate, 4a cathode and a'control grid, va nrst anti-hunting means, said means' comprising a lter network between'said last mentioned VcontrolY grid'v and cathode," said filter networkH being adapted" to' reject Ythe frequency at' whi'ch'sai'd regulator would tend"to`hunt,`ineans 'fortaking the output from the cathode Yofl'said second vacuuin "tube means through said'nrst lanti-hunting means to the"v contr'olf grid 'ef l said t'third vacuum rable core reactor to control the impedance of said alternating current portion to thereby maintain the voltage vof said'output circuit within said predetermined limits. Y

6. A highly accurate electronic voltage regulator adapted to regulate the magnitude of an alternating current voltage between predetermined limits, said regulator including an input circuit having the primary of an auto-transformer connected thereto, an output circuit associated with the secondary of said auto-transformer, a saturable core reactor having an alternating rcurrent portion and a direct current portion, means for altering the voltage across said output circuit by Varying the impedance of said alternating current portion, a bridge circuit having a special diode forming one of the arms thereof, said special diode having an arm adapted to short the diode plate to its filament in the event said lament burns out, the filament of said diode being connected across said output circuit whereby a variation in the output voltage varies the temperature of said filament to thereby imbalance said bridge, a double stage direct current amplifier having a iirst vacuum tube means and a second vacuum tube means, each of said vacuum tube means having at least a plate, a cathode anda control grid, a first filter means connected between the grid and cathode of said first vacuum tube means, a second filter means connected between the grid and cathode of said second vacuum tube means. each of said iilter means being adapted to attenuate separately alternating current ripple components superimposed on the output from said bridge circuit, means for taking the output from the cathode of said iirst vacuum tube means and applying it through said second filter means to the control grid of said second vacuum tube means, a third vacuum tube means having at least a plate, a cathode and a control grid, an anti-hunting means, said ,means comprising a filter network between' said last mentioned control grid and cathode, said filter network being adapted to reject the frequency at which said regulator would tend to hunt, means for taking the output from the cathode of ,said second vacuum tube means vthrough said anti-hunting means to the control grid of 'said third vacuum tube means to control the plate current .Y

power supply adapted to supply direct current voltage to said bridge circuit, one side of the primary winding of each of said transformers being connected to one lead of said output circuit, the other side of each of said primaries being connected to one of a pair of vacant terminals on the usual tube socket associated with said special diode, the other of said pair of terminals being connected to the other lead of said outputcircuit, a strap across the vacant terminals on said special diode which engages with the aforementioned pair of vacant terminals on said usual tube socket when said diode is in said socket whereby under such condition the primaries of said iirst and second transformers are connected `across said output circuit but in the event said diode is removed said transformers are disconnected from said output circuit to prevent the voltage across said output from exceeding the predetermined voltage and thereby preventing damage to apparatus supplied from said voltage regulator, and

- limits.

7. A highly accurate electronic voltage regulator adapted to regulate the magnitude of an alternating current voltage between predetermined limits, said regulator including an input circuit having the primary of an auto-transformer connected thereto, an output circuit associated with the secondary of said auto-transformer, a saturable core reactor having an alternating current portion and a direct current portion, means for altering the voltage across said output circuit by varying the impedance of said alternating current portion, a bridge circuit having a diode vacuum tube forming one of the arms thereof, the filament of said diode being connected across said output circuit whereby a variation in the output voltagevaries the temperature of said filament to thereby uribalance said bridge, a direct current ampliiier, iilter means associated with said direct current amplifier, means for applying the output of said bridge circuit through said filter means to said direct current amplifier whereby said iilter means is adapted to reject unwanted alternating current ripple which may be present in the output from said bridge circuit, vacuum tube means having at least a plate, a control grid, a cathode and a lament, an anti-hunting means, said means comprising a filter network between said control grid and said cathode, said filter network being adapted to reject the frequency at which said regulator would tend to hunt, means for applying the output from said direct current amplifier through said anti-hunting means to the control grid of said vacuum tube means to control the plate current thereof, a first filament transformer for supplying current to said filament, the primary of said first filament transformer being connected across said output circuit, a booster lament transformer for supplying current to said filament, the primary of said booster transformer being connected across a lead of said input circuit and a lead of said output circuit, the secondary of said booster transformer being connected in series with the secondary of said first filament transformer, the sum of the voltages across said secondaries being applied to said filament whereby under heavy initial loads a voltage appears across the primary of said booster transformer to thereby supply additional voltage to said filament enabling said filament to heat sufficiently to allow said regulator to function and upon functioning no voltage appears across said booster transformer, and means for applying the plate current of said vacuum tube means to the direct current portion of said saturable core reactor to control the impedance of said alternating current portion and to thereby maintain the voltage of said output circuit within saidpredetermined limits.

8. A highly accurate electronic voltage regulator adapted to regulate the magnitude of an alternating current voltage between predetermined limits, said regulator including an input circuit, transformer means having a iirst portion associated with said input circuit, an output circuit connected with a second portiony of said transformer means, a saturable core reactor having an alternating current portion and a direct currentportion, means for-- alteringA the Voltageacross said transformer means andthereby the output circuit by Avarying the impedance` of said alternating current portion, akbridge circuit having a diode vacuum tube forming one ci the arms thereof the filament of said diode being connected across said output circuit whereby a variation in the output voltage varies the temperature of said filament to thereby` unbalance said bridge, a double stage direct current amplifier having a first vacuum tube means and a second vacuuml tube means, each of said vacuum tube means having at least a plate, a cathode and a control grid, a first lilter means connected betweenA the grid and cathode of said first vacuum tube means, a second iilter means connected between` the grid and cathode of said second vacuum tube means, each of said lter meansv being;r adapted to attenuate separately alternating currentripplercomponents superimposed on the output lfrom said bridge circuit, means for taking-the. output from the cathode of` said rst vacuumtube means and applying it through said second iilter'means to thecontrol grid of said second vacuum tube means, a third vacuum tube meanshaving; at least a plate, a control grid, av cathode andV a filament, an anti-hunting means, saidy means comprising a filter network between said control grid and said cathode, said filter network being adapted to reject the frequency at whichv said regulator would tend to hunt, means for applying the output from said direct current amplifier through said anti-hunting means to the control grid of said vacuum tube means to control the plate current thereof, a iirst lament transformer for supplying current to saidV filament the primary of said first filament transformer being connected across said output circuit, a booster filament transformer for supplying currentY to said nlament, the primary of said booster transformer being connected across a lead of said input circuit and a lead of said output circuit, the secondary of said booster transformer beiner connected in series with the secondary of' said first nlament transformer, the sum of the volt- A' ages across said secondaries beingapplied tosaid lament whereby under heavy initial loads a voltage appears across the primary of saidbooster transformer to thereby supply additional voltage to said filament enablingl said filament to heat suiiiciently to allow said regulator to function and upon functioning no voltage armeens` across said booster transformer, and means for applying the plate current of said vacuum tube means to the direct current portion of said saturable core reactor to control the impedance of said alternating current portion and to thereby maintain the voltage of said output circuit within said predetermined limits.

9. A highly accurate electronic voltage regulator adapted to regulate the magnitude of an alternating current voltage between predetermined limits, said regulator including an input circuit having the primary of an autotransformer connected thereto, an output circuit associated with the secondary of said auto-transformer, a saturable core reactor having an alternating current portion and a direct'current portion, means for altering the voltage across said output. circuit by varying thev impedance of said alternating current portion, a bridge circuit having a special diode forming. one of the arms thereof, said special diode having an arm adapted to short the diode plate to its lilament in the event said filament burns out, the filament efeeiddiede beine;-eenileetedeereseseid output eireuit, whereby a varietiennthe Output. Voltage varies the .temperature Qtseid fllementte. thereby unbalance'said bridge, a double .stagerdirect cur# rent.v ampler having, al'ret veeuw' tubemeene @Qd .ai SBCQHQ. Vaclliullitllbe 319335 earch; 0iA Said, vacuuml tube means having" at. leastf a platea Cathode; and; a, Control grid. e tiret ltermeent eonneetedbetweenrthe erdpendeethedesef Seid rst vaeuumtube. means e Second filter means eonneetedibetween-the.gridieridieethede 0f Seid seeendvacuum. tube.- meenef, each. ef; Seid lter mea-.ris beine adapted` te attenuate.. Separately alternating current.: rippleA componente.. Seperiie nosed.;` 01.1A the Outputl from; Seid. bridge; erilit means.. for taking: the Output from., the, eethede Oi'. Said'. lSl?. VaQlllllP-tub 1113.335 am@ applying it, through said second nlter means tol thev conf tro1..grid.0f;seid Seeendsreellem tube meent., el thirdvaeuuni tube, means harige etleeet. er plete., a cathode and. a; eeritrel` grida en anti-hunting means, said means c9mprising, a filter network; between Said, lest: mentened Qontrol. grden@ cathode, saisi; filter` netwerk; beine adapted-t0 reject the frequency atwhich said regulator wouldstendtehuntf menester: taking the Output from. the: cathode Qf Said; seerld. Vacuum; time means through` eadentifhuetns; meent., 11e-the control grid of sai/d third v acu-umtube means te` control the. pleteeerrestthereet a tetftrelsformer forminglv aV portion o -f-A a power supply adapted to supply direct current voltage* toA said third vacuum tube means, aksecond transformer forminee Dertien off e newer.- Surely-adapted@ supplydirect current voltageto said bridge cir'l Cuit, 011e eide 0f theprmerrwindme ef eeen ef said transformers beingA connected to4 one lead of said output circuit, the othersideoi each of said primaries being connected to one ofl al pair of vacant-terminals on the usual tube socket as-` sociated with said specialdiopde, the other of said pair of terminals being connected to the other lead of said output circ-uit, a strap across the vacant terminals on said special diode which engages with the aforementioned pair; ofvfvvac/ant terminals on saidV usual tube socket whensaid diode is in said socket whereby under such condition the primaries of-- said first and second transformers are connected across said output circuit but in the event said diodel is removed said transformers arel `d iscormecte'd from said output circuit to prevent thevoltagev across said output from exceeding thepredetermined voltage and thereby preventingdamageto apparatus supplied from said voltage regulator, a rectifier associated with a secondaryv of said second transformer to supply direct current to said bridge, a plurality of gas-nlled electronic tubes connected across the output of said rectiiier to regulate the voltage applied to said bridge, lter means connected across said output circuit to remove third and fifth harmonic distortion and means for applying the plate current of said third vacuum tube means through the direct current portion of said saturable core reactor to control the impedance of said alternating cur-rent portion to thereby maintain the Avoltage of said output circuit within saidk predetermined limits.

10. A highlyv accurate electronic voltage regulator adapted to regulate the magnitude of an alternating current voltage between predetermined limits, said regulator. including an input circuit having the primary of an autortransformer connected thereto, an output circuit associated with the secondary of said auto-transformer, a saturable core reactor having an alternating current portion and a direct current portion, means for altering the voltage across said output circuit by varying the impedance of said alternating current portion, a bridge circuit having a diode vacuum tube forming one of the arms thereof the iilament of said diode being connected across said output circuit whereby a variation in the output voltage varies the temperature of said filament to thereby imbalance said bridge, a double stagev direct current vampliiier having a first vacuum tube means and a second vacuum tube means, each of said vacuum tube means having at least a plate, a cathode and a control grid, a rst lter network connected between the grid and cathode of said first vacuum tube means, said filter network comprising a pair of serially connected capacitors connected in parallel with a rst resistance, one end of said first resistance being connected to the grid of said rst vacuum tube means, the other end of said first resistance being connected to an output terminal of said bridge, a second resistance having one end connected to the junction of said serially connected capacitors, the other end being connected to the cathode of said first vacuum tube means, said iilter network being adapted to reject a component alternating current ripple appearing on the output voltage from said bridge, a second iilter network connected between the control grid and cathode of' said second vacuum tube means, said second filter also comprising a pair of serially connected capacitors connected in parallel with a first resistance, one end of said last mentioned iirst resistance being connected to the control grid of said second vacuum tube means, the other end being connectedv to the cathode of said first vacuum tube means, a second resistance having one end connected to the junction of the serially connected capacitors of said second lter network, the other end being connected to the cathode of said second vacuum tube means, said second iilter network being f adapted to reject a component alternating current ripple appearing on the output voltage from the cathode of said iirst vacuum tube means, a third vacuum tube means having at least a plate, a cathode and a control grid, anA anti-hunting means, said means comprising a filter network between said last mentioned control grid and cathode, said iilter network being adapted to reject the frequency at which said regulator would tend to hunt, means for taking the output from the cathode of said second vacuum tube means through said anti-hunting means to the control grid of said third vacuum tube means to control the plate current thereof, and means for applying said plate current to the direct current portion of said saturable core reactor to control the impedance of said alternating current portion and to thereby maintain the voltage of said output circuit within said predetermined limits.

11. A highly accurate electronic voltage regulator adapted to regulate the magnitude of an alternating current voltage` between predetermined limits, said regulator including aninput circuit having the primary of an auto-transformer connected thereto, an output circuit associated with the secondary of said auto-transformer, a lead of said input circuit being common with a lead of said output circuit, a satura-ble core reactor having an alternating current portion and a direct current portion, said alternat- 7;5

ing current portion being connected in series with the lead common to said input circuit and said output circuit, an inductance and a capacitance in series therewith, said combination being connected across said output circuit to remove iifth harmonic distortion from said output, a second inductance and a capacitance in series therewith, said second combination likewise being connected across said output circuit to remove third harmonic distortion from said output, a third inductance connected across said output circuit to inductively load said output circuit, a bridge circuit having a diode vacuum tube forming one of the arms thereof the iilament of said diode being connected across said output whereby a variation in the output voltage varies the temperature of said iilament to thereby unbalance said bridge, a double stage direct current ampliiier having a rst vacuum tube means and a second vacuum tube means each of said Vacuum tube means having at least a plate, a cathode and a control grid, a iirst iilter network connected between the grid and cathode of said first vacuum tube means, said filter network comprising a pair of serially connected capacitors connected in parallel with a iirst resistance, one end of said first resistance being connected to the grid of said first vacuum tube means, the other end of said rst resistance being connected to an output terminal of said bridge, a second resistance having one end connected to the junction of said serially connected capacitors, the other end being connected to the cathode of said rst vacuum tube means, said filter network being adapted to reject a component alternating current ripple appearing on the output voltage from said bridge, a second lter network connected between the control grid and cathode of said second vacuum tube means, said second filter also comprising a pair of serially connected capacitors connected in parallel with a rst resistance, one end of said last mentioned first resistance being connected to the control grid of said second vacuum tube means, the other end being connected to the cathode of said first vacuum tube means, a second resistance having one end connected to the junction of the serially connected capacitors of said second filter network the other end being connected to the cathode of said second vacuum tube means, said second filter network being adapted to reject a component alternating current ripple appearing on the output voltage from the cathode of said iirst vacuum tube means, a third vacuum tube means having at -least a plate, a cathode and a control grid, an

anti-hunting means, said anti-hunting means comprising a filter network between the control grid and cathode of said third vacuumY tube means, said filter network being similar in arrangement to said rst filter network and said second iilter network and comprising a pair of serially connected capacitors in parallel with a first resistance, one end of said first resistance being connected to the cathode of said second vacuum tube means the other end being connected to the control grid of said third vacuum tube means, a second resistance having one end connected to the junction of the last mentioned serially connected capacitors, the other end being connected to the cathode of said third vacuum tube means, said anti-hunting means being adapted to reject the frequency at which said regulator would tend to hunt, a connection from the plate of said third vacuum tube vmeans to the direct current portion of said saturable core reactor whereby the impedance of said alternating current portion is variedin accordance with the plate current through said direct current portion to thereby maintain the voltage of said output within said predetermined limits.

12. A highly accurate electronic voltage regulator adapted to regulate the magnitude of an alternating current voltage between predetermined limits, said regulator including an input circuit having the primary of an auto-transformer connected thereto, an output circuit associated with the secondary of said auto-transformer, a saturable core reactor having an alternating current portion and a direct current portion, means for altering the voltage across said output circuit by varying the impedance of said alternating current portion, a bridge circuit having a diode vacuum tube forming one of the arms thereof, the lament of said diode being connected across said output circuit whereby a variation in the output voltage varies the temperature of said lament to unbalance said bridge and vary the output thereof, an amplier connected with the output of said bridge, a second vacuum tube having at least a plate, a cathode and a control grid, means for applying the output of said amplifier to said control grid, a first transformer forming a portion of a power supply adapted to supply direct current voltage to said second vacuum tube, a second transformer forming a portion of a power supply adapted to supply direct current voltage to said bridge circuit, one side of the primary winding of each of said transformers being connected to one lead of 18 mined limits, said regulator including an input circuit, transformer means having a first portion associated with said input circuit, an output circuit connected with a second portion of said transformer means, a saturable core reactor having an alternating current portion and a direct current portion, means for altering the voltage across said transformer means and thereby the output circuit by varying the impedance of said alternating current portion, a bridge circuit having a diode vacuum tube forming one of the arms thereof the filament of said diode being connected across said output circuit whereby a variation in the output voltage varies the temperature of said filament to thereby unbalance said bridge, a plurality of variable resistors, switch means for selectively connecting said resistors in the lament circuit of said diode whereby the filament current may be varied to adapt the circuit for operation over a wide range of desired output voltages, a direct current amplier, lter means associated with said direct current amplier, means for applying the output of said bridge circuit through said filter means to said direct current amplifier whereby said lter means is adapted to reject unwanted alternating current ripple which may be present in the output from said bridge circuit, vacuum tube means, means for applying the output from said 'direct current amplier to said Vacuum tube means to control the plate current thereof. and means for applying said plate current to the direct current portion of said saturable core reactor to control the impedance of said alternating current portion and lto thereby maintain the voltage of said output circuit Within said predetermined limits.

ALLEN K. BROWN. ADOLPH O. BUNBLASKY.

REFERENCES CITED The following references are of record in the le of this patent:

UNITED STATES PATENTS Number Name Date 2,472,167 Matson -et al. June 7, 1949 2,569,500 Sorensen Oct. 2, 1951