SIEMENS ELETTRA TV2355 CHASSIS T440 INTERNAL VIEW.

The chassis is entirely based on tubes technology and it's a TELEFUNKEN developed type.

TUBES USED.

- PCF82
- PCL84
- PCF82
- PC88
- PC86
- EF183
- PCF88
- PCC189
- ECC82
- PCL84
- PCL85
- PL500
- PY83
- DY86


TUBES TV CHASSIS TELEFUNKEN

CIRCUITS DESCRIPTIONS OF TIMEBASE / DEFLECTIONS.

TELEFUNKEN TUBES HORIZONTAL DEFLECTION CIRCUIT

The present invention relates to deflection circuits of the type employed for providing a time base in connection with cathode ray tubes for deflection of an electron beam.
Magnetic deflection systems are often employed in present day systems for deflecting an electron beam in a cathode ray tube. These magnetic deflection systems employ in general two coils arranged about the neck of the cathode ray tube and in which coils saw tooth wave forms of different frequencies are generated. In one arrangement for generating saw tooth current wave forms for line deflection of TV picture tubes and with which arrangement the present invention may be advantageously used, a condenser is provided which by means of a diode which is rendered conductive during the forward stroke of the saw tooth wave form, supplies a constant voltage to the winding of an auto transformer. By means of this constant voltage, a linearly increasing current is generated in the transformer and as a result also in the deflection coil coupled thereto. The loss of energy in the deflection circuit is corn-pensated during the forward stroke of the saw tooth wave form by the final sweep amplifier, which supplies such a current !that the diode conducts during the entire for-ward stroke of the saw tooth wave form. The diode is rendered non-conductive when current flow through the final sweep amplifier is cut-off by a saw tooth synchroniz-ing impulse fed to the control grid of the final sweep amplifier tube. In particular, the final sweep amplifier is cut-off by the negative flyback of a saw tooth synchronizing impulse fed to its control grid. When the amplifier tube is cut off its anode voltage will rise, thus raising the voltage of the cathode of the diode beyond its anode voltage. The diode will therefore cease to conduct and the transformer as well as the deflecting coil and the stray capacities in. the circuit go through a free half cycle variation at the end of which, the voltage across the transformer is reversed and as a result the control diode again becomes conductive so that the above cycle may again be repeated. In addition, during the fly back period of the saw tooth synchronizing impulse, a high positive peaked voltage is developed across the transformer which is rectified by another diode. The rectified high peaked voltage is connected to the accelerat-ing anode of a cathode ray tube and serves to accelerate the electron beam in the cathode ray tube. A more detailed description of the above arrangement may be found in an article by R. Andrieu, titled, "The line deflection circuit with auto transformer" which ap-peared in a Telefunken paper, volume 95 in the year 1952. Accurate control of the sweep amplitude is an absolute requirement for line deflection circuits involving simul-taneous generation of high voltages for picture tubes. It is necessary in order to accurately control the line deflec-tion amplitude to compensate for variations in electrical value of deflection transformers, tubes, as well as for voltage source variations and the like.


The amount of deflection of the electron beam in a cathode ray tube depends not only on the amplitude of the saw tooth current wave form that flows through the deflection coil but also on the amplitude of the accelerate 5 ing voltage to which the electron beam is exposed. Since the saw tooth current wave form and the accelerating voltage are produced in the same circuit, it is obvious that an adjustment, of, for instance, the amplitude of the saw tooth current wave form will produce a con 10 comittant change in amplitude of the aLcelerating volt-age. The sweep amplitude is, on the one hand, directly proportional to the deflection current flowing through the deflection coil, and on the other hand, inversely propor-tional to the square root of the accelerating voltage. 15 It is often desired to regulate the sweep amplitude with-out affecting the focus of the electron beam on the screen of the image tube. This may be performed by ad-justing the sweep current amplitude while at the same time maintaining the high voltage, which is obtained dure 20 ing the fly back period, constant. On the other hand it may also be desired to adjust the focus of the electron beam on the screen of the picture tube. This focus adjustment may be performed by changing the magnetic field strength of a focussing magnet used with magnetical-25 ly focussed cathode ray tubes. If one, however, desires to employ a permanent magnet without additional focus-ing coils or without the necessity of adjusting the mag-netic field strength, the beam may be focussed by chang-ing the value of the accelerating voltage. However, as 30 already pointed out, a change in accelerating voltage will produce a change in the sweep amplitude, which is in-versely proportional to the square root of the accelerating voltage. Two ways are known for making the desired adjust-35 ment of the sweep amplitude. The first way concerns the adjustment of the fly back time, on which the magni-tude of the generated high voltage as well as the deflec-tion amplitude is dependent. The second way concerns the changing of the regulated anode voltage of the final 40 sweep amplifier tube in which case, the saw tooth ampli-tude will be directly proportional to the accelerating volt-age. In order to maintain a predetermined amplitude of the sweep, the saw tooth current must change as the square root of the accelerating voltage. With this rela-45 tionship of sweep current and accelerating voltage, a change in the size of the raster will result with changes in sweep amplitude. The adjustment of the anode voltage may be made, 'as known in the art, by means of a variable resistor con-50 nected in series with the anode supply voltage. The dis-advantage of adjusting the anode voltage with the above mentioned variable resistor lies in the fact that a certain amount of power will be dissipated by the resistor, thus requiring a higher initial anode supply If oltage. One of 55 the objects of the present 'invention is to provide a control arrangement for adjusting the anode voltage of the final sweep amplifier tube in such manner that additional power requirements are unnecessary. This is accomplished by making a variable connection of the anode of the final 60 sweep amplifier tube with a transformer. A uniform. adjustment is made possible by coupling the final sweep amplifier tube parallel to a portion of the transformer winding by means of two series connected inductances. The anode of the final sweep amplifier tube is connected 65 to the junction of the inductances, while the free terminals of the inductances are connected across a portion of the transformer winding, at least one of the series connected inductances being variable. With this arrangement, the two inductances can be adjusted in such manner that the 70 'total inductance of the two series connected inductances always remains constant over the adjusting range. Where the total inductance of the series connected inductances

remains constant over the adjusting range, a change in Fig. 6 shows a modification of the circuit arrangement fly back time will occur with anode voltage adjustments of Fig. 1; inasmuch as the tube capacity is transformed at the de- Fig. 7 shows yet another modification of the circuit flection coil into a greater or smaller value with the ad- arrangement of Fig. 1; and justment of the adjustable inductances. 5 Fig. 8 shows yet other curves having characteristics dif-The adjusting arrangement may on the other hand be ferent from those illustrated in Figs. 3 and 4. _so designed that the total inductance of the series con- Fig. 1 shows one example of a circuit in accordance nected variable inductances instead of being held con- with the invention and serves for explaining the opera-stant, as described above, may be so dimensioned that the tion of the circuit in accordance with the invention. It total inductance value varies in the same sense, or direc- 10 is assumed that the condenser is charged ± and — as tion, as the inductance which has its free end terminal shown in Fig. 1. The diode 2, during the forward stroke _connected to the higher alternating voltage point on the of the synchronizing impulse supplied by the sweep gen-_transformer. In this case the fly back time will remain erator 5', connects a substantially constant voltage to the constant with an adjustment of the anode voltage so that transformer winding 3 which is illustrated as being an a sharp anode voltage adjustment can be made. 15 auto transformer. As a result of the constant voltage _ In order to obtain other arbitrary adjusting charac- connected to the transformer a linearly increasing cur-teristics, it is possible to connect, for instance, at least rent is generated in the transformer winding 3 as well as in one capacitor in parallel with at least one of the two the deflecting coil 4 which is coupled to the winding 3. series connected inductances. The loss of energy in the circuit is compensated during . From the above discussion it will be apparent that 20 the forward stroke of the synchronizing by the final sweep it is an object of the present invention to provide a beam amplifier 5. The amplifier 5 supplies such a current deflection circuit for cathode ray tubes in which the to the transformer that the diode tube 2 conducts during sweep amplitude and the high direct current voltage, the entire forward stroke of the synchronizing impulse. generated in the beam deflection circuit, may be inde- When the tube 5 is cut off by the negative fly back por-pendently adjusted. 25 tion of the synchronizing impuse which has an approxi-It is yet another object of the present invention to mately saw tooth wave form, the diode 2 will likewise be provide a beam deflection circuit for cathode ray tubes cut off. As a result the transformer 3 as well as the de-in which the sweep amplitude may be varied linearly with fleeting coil 4 and stray capacities in the circuit go through relation to the high direct current voltage. a free half cycle variation, at the end of which the volt-It is yet another object of the present invention to pro- 30 age across the transformer is reversed, and as a result the vide a beam deflection circuit for cathode ray tubes in control diode 2 is again permitted to conduct. The en-which the electron beam focus may be changed by ad- tire cycle is again repeated when the forward stroke of the justing the accelerating voltage without changing, when next syunchronizing impulse reaches the control grid 1' so desired, the sweep amplitude. of the final sweep amplifier tube 5. In addition, during Yet another object of the present invention is to pro- 35 The fly back period of the saw tooth synchronizing im-vide a beam deflecting circuit for cathode ray tubes in pulse, a high positive peaked voltage is developed across which the fly-back time may be accurately controlled. the transformer winding 6 which is rectified by diode 7. With the above objects in view the present invention The inductances 8 and 9 are connected in series, the mainly consists of a deflection circuit for generating in free terminals of the inductances 8 and 9, henceforth also an inductance a current having a saw tooth wave form 40 referred to as first and second inductances, respectively, and for simultaneously generating a high direct current being connected across another portion 12 of the trans-voltage, comprising, a condenser adapted to have a direct former 3. The first and second inductances are of the current voltage across its terminals, switching means con- type which may be adjusted in opposite direction so that nected in series with the condenser for applying the volt- the total inductance L8 plus L9 remains constant over the age across the terminals of the condenser to the induct- 45 entire adjusting range. This adjustment can be effected, ance when the switching means is actuated, a transformer for instance, by winding both coils on a common cylin-having a winding a first portion of which is coupled with drical coil form having an axial bore. Within the bore the inductance, an amplifier having an anode, the ampli- may be arranged a movable ferro-magnetic core. By fier controlling the operation of the switching means, and varying the position of the core in the coil form the in-a first and a second inductance connected in series to 50 ductance of one coil will increase while the inductance of form a junction to which the anode of the amplifier tube the other will decrease. is connected, the end terminals of the first and second Fig. 2 shows curves exemplifying the different voltage inductances being connected across a second portion of relationships between accelerating voltage and deflec-the transformer winding, at least one of-the inductances tion coil voltage that may be obtained for definite rela-being variable over a predetermined adjusting range. 55 tionships between the first and second inductances. Usp The novel features which are considered as charac- represents the voltage at the deflection coil 4 obtained teristic of the invention are set forth in particular in during the forward stroke of a saw tooth wave form, and the appended claims. The invention itself, however, both is plotted along the abscissa. Ux represents the high volt-as to its construction and its method of operation, together age generated at terminal H and is plotted along the ordi-with additional objects and advantages thereof, will be 60 nate axis. The high voltage when appropriately con-best understood from the following description of specific nected to a cathode ray tube serves to accelerate the elec-embodiments when read in connection with the accom- tron beam in the cathode ray tube. If the dimensions panying drawings, in which: of the adjustable inductances are chosen so that the Fig. 1 shows a circuit diagram of a deflection circuit in total inductance LB plus L9 is not maintained constant, but accordance with the present invention: 65 is instead varied in such manner that the total inductance Fig. 2 shows the various curves obtained by plotting varies in the same sense as does the inductance Ls so that the voltage at the deflection coil versus the accelerating the transformed tube capacity at the deflection coil 4 is voltage at terminal H in the circuit arrangement of Fig. 1; compensated, then the fly back time will remain constant Fig. 3 shows the curves obtained by plotting the varia- during the adjustment. Curve 21. shown in Fig. 2 shows tions in inductance versus core displacement of a control 70 the adjusting characteristic curve obtained with the last arrangement in accordance with the invention; mentioned relationship of the inductances L8 and Ls. Fig. 4 shows another set of curves having different char- The high voltage UH is seen to increase linearly with re-acteristics from those illustrated in Fig. 3; spect to the deflection amplitude. Curve 22 shows the - Fig. 5 shows schematically, a control arrangement used deflection amplitude Up as varying with the square root in a deflection circuit, in accordance with the invention; 75 of the high voltage UH. As may be noted from curve 22,

a change in accelerating voltages Uit produces substan- ductances. Ls and L9 were adjusted in opposite direction, tially no change of the deflection amplitude. If the total that- is as the inductance of one increased the inductance inductance change is more pronounced than that used for of the other decreased, by means of a common high fre-obtaining curve 21, then the fly back time will change quency core. An independent adjustment of high voltage when an adjustment of the sweep amplitude is made. 5 and deflection amplitude could also be obtained, however, Curve 21 can be transformed into curve 23 if so desired, by an arrangement wherein the two inductances are sep-in which case, an adjustment of the inductances will arated and form two mutually independent coils each of produce no change in the high voltage UH. The man- which is variable. In this case the oppositely directed ner in which this is accomplished will be explained here- adjustment of the first and second inductances is some-inafter. 10 what more difficult to perform since in, this case, the ad-Fig. 3 illustrates in curve form the variations of the in- justment of the two inductances must be simultaneously dividual coil inductances L8, L9 as well as the variation of made. This is however no limitation since the adjust total inductance, Ls, plus L9, with relation to core ment is not made very often during actual operation. displacement X, as obtained with the circuit arrange- Fig. 7 shows yet another embodiment of the present ment of Fig. 1. It is apparent from Fig. 3 that the 15 invention in which two condensers 10 and 11 are re-change in inductance value of the first and second in- spectively connected in parallel with the coils Ls and L. ductances are in opposite direction so that the total in- By assigning suitable values to the capacitors, these ductance as a function of core displacement, remains capacitors can be used to yield any desired variable ad-constant. justing curve so that in this case also the fly back time If desired, however, the inductances may also be so 20 can be controlled simultaneously with adjustments of related so that the total inductance, L8 plus L9, changes the control arrangement in accordance with the invention in the same sense as inductance L9, as shown in Fig. zia. in a desired manner. In this case the change in total inductance can be so For certain applications it may be desired to obtain selected that the change in transformed tube capacity at an adjustment of the deflection amplitude where the high nr the deflection coil 4 will be compensated, thereby main- voltage is held constant. In order to obtain such an ad-taining the fly back time constant when the adjustment is justment, the fly back must be changed while the ad-made. justment takes place. The arrangement heretofore de-The adjusment mentioned at last always gave an ad- scribed in which condensers 10 and 11 were respectively justment along a definite curve shown in Fig. 2, namely connected in parallel with the inductances Ls and L9 may curve 21, along which curve for each deflection coil volt- 30 be used for such purpose. age Usp there exists a corresponding definite high_ voltage As already noted it is also possible to adjust the hod-Urr. zontal sweep amplitude while holding the high voltage In accordance with another aspect of the invention both constant by means of an arrangement in which only in-mentioned magnitudes UH and Usp are adjusted independ; ductances are used as circuit elements. ently of one another. In this case the first and second 30 By increasing the coil spacing in an arrangement where inductances are arranged to be independently adjustable. the inductance values of the first and second inductances Such independent adjustments of the high voltage UH are changed in opposite directions as a function and of the deflection coil voltage Up may be effected with of core displacement as in Fig. 3, a curve of the in-the circuit arrangement illustrated in Fig. 1. To make ductance variations may be obtained such that the total such independent adjustments of the high voltage and the 40 inductance is considerably changed when making an ad-deflection coil voltage possible, the oppositely directed justment, which produces a considerable change in fly adjustments of the inductances Ls and L9 may be effected back time, while one of the inductances changes in value through the displacement of a high frequency core in the only slightly during the adjustment, as shown in Fig. 8. common coil axis, in which case, one of the two coils is Experiment has shown that it is possible with an ar-constructed as compared with the other, so that said one t.' rangement which exhibits the curves shown in Fig. 8 to coil may be spatially displaced along the coil form with hold, without any difficulty, the high voltage constant relation to the other. Fig. 5 shows an arrangement over an adjusting range of wherein one of the two coils may be displaced with rela- Another control arrangement in accordance with the tion to the other in accordance with the invention. Both invention, exhibiting an adjusting characteristic curve 50 coil sections L8 and L9 of the inductive voltage divider corresponding to that of Fig. 8 may be used, and which are arranged on a common coil form 31 and in such man- involves the connection of a fixed inductance of suitable ner that the coil, or inductance Ls, is rigidly secured to magnitude in parallel with the coil La. In Fig. 6 the the coil form 31 while the coil, or inductance, L8 is ar- parallel inductance is designated by reference numeral 13, ranged to be displaced in direction of the axis. Inside the 55 and shown therein as being adjustable, which together tubular coil form 31 is arranged a displaceable hi211 fre- e with coil 8 forms the inductance LEI In this case also, quency core 32 which serves to change the coil induc- the high voltage, when adjusting the inductances Ls, L92 tances Ls and L9 in opposite sense, that is, as one in- remains constant without having to make any adjust-creases, the other decreases. It is possible to obtain with ment of the inductance 13. As may be noted from Fig. 8 this arrangement, adjustments which will follow curves 60 the inductance L8 with displacements of the core is not 21, 22 or 23 of Fig. 2. It is also possible to obtain a high materially changed. voltage amplitude and a deflection amplitude of any value If the control arrangement in accordance with the ma with this control arrangement. As a iesult the need for vention employs an adjustable inductance L9 which is adjusting of focusing magnets to obtain a sharp beam connected in series with a fixed inductance Ls, then when focus is• overcome since a sharp focus setting may be 65 an adjustment is made, a change in deflection amplitude obtained with the control arrangement in accordance with may also be effected while simultaneously maintaining the invention by changing the high voltage level. the high voltage substantially constant. Fig. 6 shows another embodiment of the invention in The invention is not limited to the described embodi-which is connected in parallel with the inductance L8 an ments but may be used with deflection circuits which do independently adjustable inductance 13. The circuit 70 not involve the use of auto transformers but operate arrangement illustrated in Fig. 6 is similar to that of instead with any other type of standard transformer. Fig. 1 in all other respects. The inductance 13 makes it It will be understood that each of the elements de-possible to adjust the horizontal sweep amplitude while scribed above, or two or more together, may also find a the high: voltage is maintained at a constant level. useful application in other types of deflection circuits in all of the arrangements described up to now the in- 75 differing from the types described above.

While the invention has been illustrated and described 'as embodied in magnetic deflection circuits, it is not in--tended to be limited to the details shown, since various 'modifications and structural changes may be made with-out departing in any way from the spirit of the present invention. . Without further analysis, the foregoing will so fully reveal the gist of the present invention that others can by applying current knowledge readily adapt it for vari-ous applications without omitting features that, from the standpoint of prior art, fairly constitute essential charac-leristics of the generic or specific aspects of this inven-tion and, therefore, such adaptations should and are in-tended to be comprehended within the meaning and range of equivalence of the following claims. 7_ What is claimed as new and desired to be secured by Letters Patent is: 1 1. A deflection circuit for generating in an inductance _a current having a sawtooth wave form and for simul- taneously generating a high direct current voltage, corn- , . -prising in combination, a condenser adapted to have a rdirect current voltage across its terminals; switching means connected in series with said condenser for ap-plying said voltage across said terminals of said con-'denser to the inductance when said switching means is -actuated; a transformer having a winding a first portion of which is coupled with the inductance; an amplifier having an anode, said amplifier controlling the operation of said switching means; and a first and a second in-ductance connected in series to form a junction to which -said anode of said amplifier tube is connected, the end terminals of said first and second inductances being con-nected across a second portion of said transformer wind-ing, at least one of said first and second inductances _being variable over a predetermined adjusting range. 2. A deflection circuit for generating in a first in--ductance a current having a saw tooth wave form and for simultaneously generating a high direct current voltage, comprising in combination, a condenser adapted to have a direct current voltage across its terminals; switching means connected in series with said condenser for ap-plying said voltage across said terminals of said con-denser to the first inductance when said switching means is actuated; a transformer having a winding a first por-tion of which is coupled with the first inductance; an amplifier tube having an anode and controlling the opera-tion of said switching means; and a pair of adjustable inductances connected in series to form a junction to which said anode of said amplifier tube is connected, the end terminals of said pair of inductances being con-nected across a second portion of said transformer wind-ing, said pair of inductances being arranged with respect -to each other to be simultaneously adjustable in op-posite directions so as to yield a total inductance which is constant over the entire adjusting range. 3. A deflection circuit for generating in an inductance a current having a sawtooth wave form and for simul-taneously generating a high direct current voltage, com-prising a combination, a condenser adapted to have a di-rect current voltage across its terminals; switching means connected in series with said condenser for applying said voltage across said terminals of said condenser to the inductance when said switching means is actuated; a trans-former having a winding a first portion of which is coupled with the inductance; an amplifier having an anode, said amplifier controlling the operation of said switching means; a first and a second inductance connected in series to form a junction to which said anode of said amplifier tube is connected, the end terminals of said first and second inductances being connected across a second por-tion of said transformer winding, at least one of said first and second inductances being variable over a pre-determined adjusting range; and at least one condenser

connected across at least one of said inductances for se-lecting a desired adjusting curve. 4. A deflection circuit for generating in an inductance a current having a saw tooth wave form and for simul-taneously generating a high direct current voltage, comprising in combination, a condenser adapted to have a direct current voltage across its terminals; switching means connected in series with said condenser for applying said voltage across said terminals of said condenser to the inductance when said switching means is actuated; a transformer having a winding a first portion of which is coupled with the inductance; an amplifier having an anode, said amplifier controlling the operation of said switching means; a first and a second inductance connected in series to form a junction to which said anode of said amplifier tube is connected, the end terminals of said first and second inductances being connected across a second por-tion of said transformer winding, at least one of said first and second inductances being variable over a predeter-mined adjusting range; and a third adjustable inductance connected in parallel with one of said first and second inductances. 5. A deflection circuit for generating in a first induc-tance a current having a saw tooth wave form and for simultaneously generating a high direct current voltage, comprising in combination, a condenser adapted to have a direct current voltage across its terminals; switching means connected in series with said condenser for apply-ing said voltage across said terminals of said condenser to the first inductance when said switching means is actuated; a transformer having a winding a first portion of which is coupled with the first inductance; an amplifier tube hay-ing an anode and controlling the operation of said switch-ing means; and a pair of adjustable inductances connected in series to form a junction to which said anode of said amplifier tube is connected, the end terminals of said pair of inductances being connected across a second portion of said transformer winding, said pair of inductances being arranged with respect to each other to be simul-taneously adjustable in opposite directions so as to yield a total inductance which is constant over the entire ad-justing range, said pair of inductances forming control means for changing the amplitude of the sawtooth wave form while the high direct current voltage remains sub-stantially constant. 6. A deflection circuit for cathode ray tubes employing electro-magnetic deflecting coils comprising, in combina-tion, an output transfoi mer, the electro-magnetic deflect-ing coils being coupled to a first portion of said output transformer; a switching diode; a boost condenser, said diode and said condenser being connected in series across a second portion of said output transformer to develop across said boost condenser a voltage representative of recovered energy cyclically stored in the deflection cir-cuit; a deflection output tube having at least an anode and a cathode; a first and a second inductance connected in series to form a junction, the end terminals of said first and second inductances being connected across a third portion of said output transformer, the junction of said first and second inductances being connected to the anode of said deflection output tube, said inductances having windings adapted to be wound about a tubular coil form; and a high frequency core adapted to be slidably mounted inside the tubular coil form to change the in-ductance values of said two inductances in opposite di-rections. 7. A deflection circuit for cathode ray tubes employ-ing electromagnetic deflecting coils comprising, in com-bination, an output transformer; a deflection output tube, having at least an anode and a cathode, the electromag-netic deflecting coils being coupled to the anode-cathode circuit of said output tube through said output transform-er; a switching diode; a boost condenser, said diode and said condenser being connected in series across a first


portion of said output transformer to develop across said boost condenser a voltage representative of recovered energy cyclically stored in the deflection circuit; and means for adjusting the amplitude of the deflection volt-age for the cathode ray tubes, said means including a 5 pair of inductances connected in series across a second portion of said output transformer and having a junction point, the anode of said deflection output tube being con-nected to said junction point, at least one of said series con-nected inductances being adjustable to provide a variable 10 coupling between said output tube and said output trans-former. 8. A deflection circuit for cathode ray tubes employing electro-magnetic deflecting coils comprising, in combina-tion, an output transformer, the electromagnetic deflecting 15 coils being coupled to a first portion of said output trans-former; a switching diode; a boost condenser, said diode and said condenser being connected in series across a second portion of said output transformer to develop across said boost condenser a voltage representative of 20 recovered energy cyclically stored in the deflection circuit; a deflection output tube having at least an anode and a cathode; a first and a second inductance connected in series to form a junction, the end terminals of said first and second inductances being connected across a third por-ton of said output transformer, the junction of said first and second inductances being connected to the anode of said deflection output tube; means for adjusting at least one of said first and said second inductances to vary the inductance thereof through a predetermined range; and a first and second condenser connected respectively across
said first and second inductances for selecting a desired inductance adjusting curve. 9. A deflection circuit for cathode ray tubes employing electromagnetic deflecting coils comprising, in combina-tion, an output transformer; a deflection output tube, having at least an anode and a cathode, the electromag-netic deflecting coils being coupled to the anode-cathode circuit of said output tube thrcugh said output transformer; a switching diode; a boost condenser, said diode and said condenser being connected in series across a first por-tion of said output transformer to develop across said boost condenser a voltage representative of recovered energy cyclically stored in the deflection circuit; rectifier means connected to a winding of said output transformer to derive a high voltage from voltage pulses cyclically arising in said output transformer; and means for adjust-ing the amplitude of the deflection voltage for the cath-ode ray tubes, said means including a pair of inductances connected in series across a third portion of said output transformer and having a junction point, the anode of said deflection output tube being connected to said junc-tion point, said pair of inductances being simultaneously adjustable in opposite directions to give a total inductance which is constant over the entire adjusting range.


TELEFUNKEN TUBES Vertical deflection television circuit:The present invention relates ge

nerally to circuits for
cathode ray tubes which generate saw tooth current curves,
and especially for the vertical deflection of one or several
electron beams in the picture tube of a television receiver,
wherein during the forward cource of the saw tooth curve
the ohmic voltage is high compared to the inductive volt‑
age.
In some cathode ray tube (CRT) circuits, the deflecting
coils at the line frequency, during the forward deflection
of the saw tooth deflecting current, are mostly inductive.
This is not true for the lower frequencies of vertical de‑
flection. In the latter case, the deflecting coils provide a
substantially ohmic resistance having but a small inductive
component. However this is not always true with the more
rapid fly-back pulse.
To produce a linear increase of the coil current during
forward deflection, a linear increase of the coil voltage
is also necessary. This increase is provided by a tube
either coupled directly I to the coil or through a trans‑
former. The control voltage is produced by an RC-circuit
which discharges through a tube, such as a blocldng oscil‑
lator. When using transformer coupling, it is usual to
employed relatively small transformers, for reasons of
economy, and because of this the deflecting current curve
in the coils deviates considerably from a saw tooth curve.
It is known that in order to achieve a linear rising flank
Of the saw tooth current curve, it is advantageous to pro‑
vide the charging capacitor with a frequency dependent
negativeS feedback from the transformer or from the anode
circuit of the tube. Such a negative feedback has been 40
provided in known circuits by means of a capacitive volt‑
age divider connected between the transformer, or anode,
and the charging capacitor. The tapping point of this volt‑
age divider is connected to a point of substantially axed
voltage through one or several resistors. By a substantial- 45
ly fixed voltage, is meant a voltage which has only slight
fluctuations with respect to the voltage which has only
slight fluctuations with respect to the voltage on the other
side of the resistance. The capacitive voltage divider is ,n
so designed that the first • capacitor in the negative feed-
back path, together with the resistance connected in the
shunt path forms a differentiating section which reduces
the negative feedback for the lower frequencies. By this
means the defects and deviations from a saw tooth curve r„
brought about by the finite inductance of the transformer,
are corrected. The remainder of the capacitive voltage
divider forms an integrating section which renders the neg‑
afive feedback voltage proportional to the current flowing
in the deflecting coils and filters out the fly-back peaks.
When using a CRT having a radius of screen curvature 60
which is greater than the distance from the screen to the
center of deflection of the vertical deflecting coils, there
is tangent error (flat screen) distortion. To obviate this
distortion the deflecting current is rendered S-shaped, by
altering the shape of the curve of the control grid voltage 65
of the tube in whose anode circuit the coil is situated,
while the effective voltage of the charging circuit is altered.
The S-shape distortion of the control voltage curve has

also been provided in the past by connecting the remote
end of the charging resistor with respect to the capacitor
through an integrating circuit with the anode of the con‑
trolled tube. The time constant of this circuit is at least
double the duration of the period of one scanning.
However, with this circuit it is not possible to compen‑
sate for the tangent error while operating the transformer
at optimum conditions. The tangent error distortion could
be compensated for in the lower half of the picture by pro‑
viding a lesser preliminary correctiOn of the distortion of
the control voltage and compensating for the expansion
thus caused in the upper half of the picture through the
adjustable integrating section. However, the region of the
picture affected by this section amounts to only a few
lines at the upper border }of the picture and this method
is therefore not useful for correction of the tangent error
distortion.
With these defects of the prior art in mind, it WI main
object of this invention to provide a circuit for elitninating
tangent error distortion.
Another object is to provide such a circuit wherein
there is predistortion of the control potential to aid in cor‑
reeling tangent error distortion and which may be adjusted
to be a minimum or even eliminated.
These objects and others ancillary thereto are accom‑
plished according to preferred embodiments of the inven‑
tion, wherein a circuit is provided for eliminating tangent
error distortion and rendering the rising flank of the saw
tooth curve linear. The circuit includes a frequency de‑
pendent negative feedback section coupled to a capacitive
voltage divider. A linearity regulator is connected between
the tapping point of the capacitive voltage divider and a
substantially fixed voltage for correcting the tangent error
distortion, and is connected as well with one or more cirs
cult elements, providing an additional predistortion of the
control voltage. This is done in such a manner that when
the linearity regulator is short-circuited this predistortion
is disconnected or at a minimum.
In a preferred embodiment an additional resistance is
connected between the anode of the tube feeding the coils
and a tapping point of a first resistance connected between
the capacitive voltage divider and the point having a sub‑
stantially constant voltage. The first resistance is variable
so that the balance between the linearity in the lower and
upper halves of the picture and the compensation for the
tangent error distortion may be adjusted. Thus, an un‑
distorted portion of the anode AC. voltage of the tube
is applied to the tapping point of the voltage divider, i.e.,
the integrating section. This portion of the A.C. voltage
reduces the frequency dependent negative feedback in the
latter portion of the curve corresponding to the lower
border of the picture, and increases this feedback in the
first portion of the forward deflection of the saw tooth
curve. When the regulator is short-circuited the undis‑
torted portion for the negative feedback is zero.
Additional objects and advantages of the present in‑
vention will become apparent upon consideration of the
following description when taken in conjunction with the
accompanying drawings in which:
FIGURE 1 is a circuit diagram of the vertical deftec:•
lion circuit comprising the present invention.
FIGURE 2 are curves provided by various sections of
the circuit of FIGURE 1 and which are labeled a, b, c,
and d.
FIGURE 3 is a circuit diagram of a vertical deflection
circuit which has actually been constructed and used.
FIGURE 4 is a circuit diagram of another embodi‑
ment of the invention.

FIGURE 5 is a circuit diagram of a further embodi- rection of the tangent error distortion. Inasmuch as the ment. regulator 12 acts as a balancing regulator, the intensified FIGURE 6 is a circuit diagram of still another embodi- differentiation produced for the upper half of the picture ment. at the same time influences the lower half of the picture. With more particular reference to the drawings, FIG- 5 In known circuits, which do not use resistor 15, such a URE 1 illustrates a theoretical vertical deflection circuit selection of the differentiating section would manifest it-wherein the deflecting coils 1 are connected through a self as a marked expansion of the lower half of the 'picture. transformer 2 with the anode 40 of an amplifying tube 3. However, with the use of resistor 15, an additional Ire-The anode 40 is connected with the operating voltage quency dependent negative feedback is introduced which + VB through the primary winding 4 of transformer 2. 10 has a greater effect in the upper half of the picture than A control voltage having a saw tooth shaped curve is fed in the lower half of the picture. This is so because the from a charging capacitor 5 through :a coupling capacitor anode A.C. voltage is greater. 6 to the control grid of the amplifier tube. This voltage When regulator 12 is short-circuited, the greatest effect is obtained from RC-circuit 7, 5 whereby capacitor 5 is is obtained from the differentiating section 9, 11, 12 and charged through resistor 7 and discharged through block- 15 the cutoff frequency is at its highest. Also, the crowding ing oscillator 3. of the lines at the beginning of the picture and the ex-A negative feedback section or channel is connected pansion of the lines at the end of the picture are the between anode 40 and control grid 41 of tube 3 for render- greatest. The above-mentioned portion of the undis-ing linear the current which flows through deflecting coils torted anode A.C. voltage is zero. If the value of re-1 and which has a saw tooth shaped curve. 20 sistance 12 is increased, the differentiation action is This feedback section comprises a capacitive voltage lessened and the expansion of the lines is uniformly re-divider including capacitors 9, 10, and two resistors 11, 12 duced. Also the undistorted portion of the anode AC. connected between the point c, which is the junction of voltage at point 14 becomes noticeable and this primarily capacitors 9 and 10 and ground. Resistor 12 is variable. has a delaying effect on the upper half of the picture. Furthermore, a variable resistor 13 is connected between 25 Curve d of FIGURE 2 shows the control grid voltage of the capacitor 10 and coupling capacitor 6 or charging tube 3. capacitor 5. A resistor 15 is connected between junction FIGURE 3 illustrates a circuit constructed in accord-noint 14 of resistors 11, 12 and anode 40 or point b ance with the present invention which has actually been of the negative feedback channel to attenuate the voltage constructed and used. The values of the various corn-in differentiating sections 9, 11 and superposes an undis- 30 ponents are indicated in the drawing. torted portion of the voltage, having a saw tooth curve, FIGURE 4 illustrates a further embodiment of the from the tube 3 on point c. Junction point 14 may be invention wherein corresponding elements are identified connected with junction point 18 of capacitor 10 and with the same reference numerals used in connection with. resistor 13 through capacitor 16 and resistor 17. A grid FIGURE 1. In this embodiment the linearity regulator leak resistor 19 is provided for tube 3. Resistor 21 and 35 is provided in the shunt branch of the capacitive volt-capacitor 20 form the RC-section for the cathode circuit age dividers 9, 10. This is accomplished by connecting of tube 3. One terminal of the charging capacitor is a resistor 25 in parallel with a series circuit including a connected to the junction of the RC-section 20, 21, with variable resistor 26 and a resistor 27. The tapping point the cathode 42 of the tube 3. 28 of this series circuit located between resistors 26 and The operation of this circuit will now be explained 40 27 is connected with anode 40 through capacitor 29. W with reference to the curves of FIGURE 2. To eliminate When regulator 26 is short-circuited, capacitors 9 and tangent error distortion, the voltage at charging capacitor 29 are connected in parallel. In this case the resistors 5, which is rising according to an e-function, is distorted 25 and 27 are also connected in parallel and the differ- by a frequency dependent negative feedback to such an 45 entiating section has its highest cutoff frequency. When extent that the saw tooth curve of the current in the coils resistor 26 is increased the total resistance in the shunt considered from the center of the picture becomes con- branch increases and capacitor 29 has less effect so that tinuously decreased relative to the linear course. An S- the cutoff frequency continuously becomes lower. This shaped component is superimposed on the linear portion occurs because the total resistance is increasing faster of the curve. The curve of the voltage due to the nega- than the capacitance is decreasing. By this means, the tive feedback at charging capacitor 5 is illustrated by lines in the lower half of the picture are crowded together curve a of FIGURE 2. The curve of the anode A.C. more than the lines in the upper half of the picture are voltage of tube 3 at point b is illustrated in curve b. This expanded, and, considering the entire picture, the middle voltage is differentiated by RC-section 9, 11, 12, so that is expanded and the upper and lower halves are corn- 55 the low frequencies in the negative feedback section be- pressed. come ineffective, i.e., attenuated. In selecting values of resistors 25, 26, and 27, resistor By means of integrating sections 13, 6, 5, the fly-back 25 must be large with respect to resistor 27, and the pulse, such as 22 in curve c, FIGURE 2, is filtered out parallel circuit including these resistors should be about and the negative feedback voltage fed to the control 100,000 ohms, while the parallel circuit including capaci- grid 41 is rendered approximately proportional to the cur- nr, tors 9 and 29 should be about 33 nanofarads (1 nanofarad tiU rent in the deflection coils. Furthermore, the anode A.C. equals 10-9 farads). voltage passes through resistor 15 to tapping point 14 FIGURE 5 illustrates another embodiment of the in- of voltage divider 11, 12. Thus, the resistors 12, 15 serve vention wherein the linearity regulator 12 is mechanically as a voltage divider for the undistorted anode AC. voltage coupled with a variable resistor 30 which together with resistor 19' forms the grid leak resistance 19. Thus, the and they determine the value of the portion of this voltage "r, r linearity of the control voltage fed to the control grid fed to tapping point c. The voltage curve at point c is shown in curve c of FIGURE 2. The dashed line shows of tube 3 may be varied in accordance with the position of the linearity regulator. the curve after resistor 15 has been inserted into the FIGURE 6 illustrates a further embodiment wherein circuit. on the tap of the ohmic voltage divider connected in the The greater steepness in the first portion of the fore 70 shunt circuit of the capacitive voltage divider, a grid leak ward deflection is a result of both the portion of the resistance 19 is connected. Grid leak resistance 19 in- anode A.C. voltage as well as the increased differentiation eludes a potentiometer 31 directly connected to the tap, action of section 9, 11, 12. This is required to attain a as well as a resistor 19'. The movable contact of this gradually decreasing crowding of the lines from the start potentiometer is connected with the substantially constant to the middle of the picture and this is desired for cor- 75 voltage which is ground.

In the circuits of FIGURES 5 and • 6 resistor 15 of FIGURE 1 may be inserted if desired. It will be understood that the above description of the present invention is susceptible to various modifications, changes and adaptations, and the same are intended to be comprehended within the meaning and range of equiva-lents of the appended claims. What is claimed is: • A circuit arrangement for producing a current having a saw tooth shaped curve for the deflection of an electron beam of a CRT wherein theI radius of curvature of the screen is greater than its distance from the center of deflection, comprising an output circuit having deflecting coils presenting an ohmic load with an inductive comp-nent for the saw tooth current, tube means connected to said output circuit and having an anode and a control grid for generating a saw tooth control voltage; capacitive voltage divider means including two capacitors connected to the tube anode for predistorting the saw tooth control voltage with frequency dependent negative feedback which is fed to the control grid; a variable linearity regulator having a tapping point and connected to a tapping point of the capacitive voltage divider between the two capaci-• tors and a substantially fixed voltage for correcting the tangential 'distortion; and at least one circuit element means connected with said regulator to bring about an additional predistortion of the control voltage so that when the linearity regulator is short-circuited the addi-tional predistortion is minimal. 2. A circuit arrangement according to claim 1, com-prising an ohmic resistance connected between said tube anode and the tapping point of the linearity regulator. 311 A circuit arrangement according to claim 1, compris-ing a resistance forming a shunt branch with respect to the capacitive voltage divider; a series circuit including• a variable and a fixed resistance connected in parallel with the shunt branch resistance; and a capacitor con-nected between the tapping point of said series circuit and the tube anode. 4. A circuit arrangement according to claim 1, corn-prising a resistance forming a shunt branch with respect to the capacitive voltage divider; a grid leak resistance including a fixed and a variable resistor, connected_ to the shunt branch resistance, a movable contact of said variable resistor being connected to ground. 5. A circuit arrangement according to claim 1, corn-prising a variable grid leak resistor connected between ground and the control grid, said linearity regulator be-ing mechanically coupled to the grid leak resistor for simultaneous adjustment. •6. A circuit arrangement for producing a current having a saw tooth shaped curve for the deflection of an electron beam of a CRT wherein the radius of curvature of the screen is greater than its distance from the center of deflection, comprising an output circuit having deflecting coils presenting an ohmic load with an inductive compo-nent for the saw tooth current, tube means connected to said output circuit and having an anode and a control grid for generating a saw tooth control voltage; capacitive voltage divider means including two capacitors connected to the tube anode for predistorting the saw tooth control voltage with frequency dependent negative feedback which is fed to the control grid; a variable linearity regulator having a tapping point and connected to a tapping point of the capacitive voltage divider between the two capaci-tors and a substantially fixed voltage for correcting the tangential distortion; and at least one circuit element means connected with said regulator to bring about an additional predistortion of the control voltage so that when the linearity regulator is short-circuited the addi-tional predistortion is eliminated. 7. In a circuit arrangement using a tube for producing a saw tooth shaped current curve for the magnetic deflec-tion of one or several electron beams of a CRT, in which

the radius of curvature of the picture screen is greater than its distance from the center of deflection, the output circuit including deflecting coils which present an ohmic load with an inductive component for the saw tooth cur-5 rent, and to the control grid of which is fed a saw tooth shaped control voltage, obtained through a periodic charge and discharge of a capacitor, predistorted through a frequency dependent negative feedback by means of a capacitive voltage divider, the improvement comprising 10 a linearity regulator inserted between the tapping point of the capacitive voltage divider and a substantially fixed potential for correction of the tangential distortion, said linearity regulator being connected with at least one circuit element means bringing about an additional predistortion 15 of the control voltage in such a manner that when the linearity regulator is shortcircuited, the additional pre-distortion is minimal or is cut off. 8. A circuit arrangement according to claim 7, comprising a resistance connected as a shunt branch to the capaci-tive potential divider, the series connection of an adjust-able and fixed resistance being connected in parallel with said shunt branch resistance, the tapping point of the series connection being connected over a capacitor with the anode of the tube. 25 9. In a circuit arrangement for producing a current having a saw tooth shaped curve for the deflection of an electron beam of a CRT wherein the radius of curvature of the screen is greater than its distance from the center of deflection, and including tube means having an anode 30 and a control grid, an output stage for the tube means having deflecting coils presenting an ohmic load with an inductive component for the saw tooth current, load capacitor means connected to be periodically charged and discharged to apply to the control grid of the tube means 35 a voltage having a saw tooth shaped curve, feedback means connected between the tube means anode and the tube means control grid for applying a frequency depend-ent negative feedback to the control grid for predistorting the saw tooth shaped control voltage and including two 40 series connected capacitors, and a linearity regulator in-cluding a variable resistor connected from the connection point between the capacitors to a point of substantially fixed potential, the improvement comprising means con-nected to the tube anode and to the linearity regulator 45 for applying a voltage from the anode to the linearity regulator in a substantially undistorted manner to provide an additional predistortion of the control voltage effective at the control grid of the tube for eliminating the tangen-tial error, which voltage exceeds the amount to be used 50 for linearizing the deflection current, said regulator hav-ing a short circuited position in which said anode voltage is substantially zero. 10. In a circuit arrangement for producing a current having a saw tooth shaped curve for the deflection of an 55 electron beam of a CRT wherein the radius of curvature of the screen is greater than its distance from the center of deflection, and including tube means having an anode and a control grid, an output stage for the tube means having deflecting coils presenting an ohmic load with an 60 inductive component for the saw tooth current, load capacitor means connected to be periodically charged and discharged to apply to the control grid of the tube means a voltage having a saw tooth shaped curve, feedback means connected between the tube means anode and the 65 tube means control grid for applying a frequency depend-ent negative feedback to the control grid for predistorting the saw tooth shaped control voltage and including two series connected capacitors, and a linearity regulator in-eluding a variable resistor connected from the connection 70 point between the capacitors to a point of substantially fixed potential, the improvement comprising coupling means for connecting the load capacitor to the tube means for providing an additional predistortion of the control voltage effective at the control grid of the tube means 75 for eliminating the tangential error, which voltage exceeds
the amount to be used for linearizing the deflection cur-rent, said coupling means being variable to vary

the time constant thereof independently of the effect of negative feedback, said regulator having a short circuited position in which the additional predistortion of the control volt-age is substantially zero.

Constant potential transformer / Constant Voltage transformer :

 The old B/W Tubes Television set was powered with a External Voltage stabiliser / Constant Voltage transformer unit (portable metal box) because  There was intermittent significant rapid line voltage dips here and there that were rather annoying when watching a tube set with an unregulated power supply (like all tvs of ancient times) and it eliminates the line dip issue completely.

(The, of mine, Pictured Constant Voltage transformer unit taken as example is a "KURTIS" STV/3 Italian Manufactured in Milan (Italy) in Year 1954 with a 250 VA power displacement and developed under Italian Patent 50499. It's clearly reported that input may be universal within -20%  +10% variations, output is precisely regulated within 1% range.........................click on pictures to enlarge them at full screen......)

The invention relates to voltage regulators of the type employed to supply alternating current and a constant voltage to a load circuit from a source in which the line voltage varies. They are particularly advantageous in connection with commercial applications such as amplifiers for talking motion pictures, amplifiers for radio transmitters,  Television sets (tubes),   mercury arc lamps, X-ray apparatus, etc.







 
Features : Instantaneous Voltage regulation. No effect of input Transient and spikes on the output. Sinusoidal output waveform. Was a  perfect answer and remedy for all types of electronic equipment. The  CVT have been designed to give you total protection against power related problems and to condition the power to suit the needs of Tubes television sets based equipment. It effectively regulates voltage variation, suppresses transients and bridges short interruptions/dips.

Basics: Ferro Resonant type Constant Voltage Transformers - CVT, the AC mains power the input winding, which The input winding normally runs at very moderate Flux linkage levels. The output winding exhibits an intrinsic energy characteristic and this energy storage operate in conjunction with mains capacitor to produce self-generated AC flux Field which is indirectly extracted from the Input Winding.
These Constant Voltage transformer or CVT use a tank circuit composed of a high-voltage resonant winding and a capacitor to produce a nearly constant average output with a varying input. The ferroresonant approach is attractive due to its lack of active components, relying on the square loop saturation characteristics of the tank circuit to absorb variations in average input voltage.

The ferroresonant action is a flux limiter rather than a voltage regulator, but with a fixed supply frequency it can maintain an almost constant average output voltage even as the input voltage varies widely.

All problems related to variation / fluctuation in Voltages are effectively handled because of this principle and a constant voltage output of ± 1% is given.

 INVENTOR: JOSEPH G. SOLA.

The  invention relates to an improved constant potential transformer by means of which variations of input voltage over a wide range of limits may take place without affecting the output voltage to any substantial extent.

One of the objects of my invention is to provide a constant potential transformer which is compact as a unit and which may be economically manufactured.

o1 It is another object of my invention to provide a transformer of this type in which the efficiency and input power factor are high while the temperature rise of the magnetic core is low.

A further object of my invention is to provide 1., a transformer, the outputvoltage wave of which will have very little distortion and the device will be satisfactory for various commercial applications.

The invention consists of the novel constructions, arrangments and devices to be hereinafter described and claimed for carrying out the above stated objects and such other objects as will appear from the following description of certain preferred embodiments illustrated in the accompanying drawings, wherein,Fig. 1 is a sectional view of one form of construction that may be used; Fig. 2 is a diagrammatic illustration of the wiring arrangement that may be used in connection with a construction such as that shown in Fig. 1; Fig. 3 is a sectional view of another form of construction embodying the principles of my invention; Fig. 4 is a diagrammatic illustration of the wiring arrangement that may be used in connection with a construction such as that shown in Fig. 3; Fig. 5 is a diagram showing the vector relations between the various voltages obtained in the illustrated constructions at different values of input voltage; and Fig. 6 is a graph showing the relation between the magnitudes of various voltages obtained in the illustrated constructions as the input voltage is varied.

Like characters of reference designate like parts in the several views.

Referring to Figs. 1 and 2, it will be seen that a core type of transformer construction is illustrated, the closed magnetic circuit 10 of which comprises a stack of I-shaped laminations II in abutting relation with the end legs 12a of a stack of E-shaped laminations 12, which may be held 5 together by any suitable means. On the end portion A of the core bar 11, I have provided a primary winding 13, the terminals 14 and 15 of which are adapted to be connected with a source of alternating current, the voltage of which from time to time may fluctuate or vary substantially. g On the end portion B of the core bar 11, I have mounted a winding 16, which is in spaced relation to but magnetically coupled with the winding 13, the winding 16 having terminal leads 17 and 18 and an intermediate tap 19. That part of the winding 16 between the lead I7 and tap 19 may be considered as an output or load winding, and the entire winding 16 between the leads 17 and 18 may be termed an intermediate winding.

The magnetic core 10 is provided with a high leakage reactance path between the windings 13 and 16 which in the form shown comprises the central leg 12b of the E-shaped laminations and which terminates short of the core bar 1 thereby providing a non-magnetic or air gap 20 between said leg 12b and the core bar II. In this arrangement, a condenser 21 is connected by leads 22 across the terminals 17 and 18 of the winding 16.
The lead 17 forms one side and the tap 19 the other side of what may be termed an output or load circuit. In the arrangement shown, an auxiliary winding 23 is positioned over the winding 13 and is magnetically coupled therewith, the terminals 24 of said winding 23 being connected in series in the lead 19 of said output circuit. In Figs. 3 and 4, I have illustrated my invention in connection with a well-known shell type of transformer having two closed magnetic circuits 10 and 10a comprising a straight central core bar 25 of I-shaped laminations, the sides of which are in abutting contact with the end legs 26a of the E-shaped laminations 26 and the end legs 27a of the E-shaped laminations 27, said parts being held in operative relation by any suitable means. On the end portion A, of the core bar 25, I have mounted a primary winding 28 the terminals 29 and 30 of which are adapted to be connected to a source of alternating current, the voltage of which may fluctuate substantially from time to time. Another winding 31 is positioned on the end portion B of the core bar 25, the winding 31 being in spaced relation to but magnetically coupled loosely with the winding 28.

A condenser 32 is connected across the terminals 33 and 34 of the winding 31. Another winding 80 35 is mounted on the end portion B of the core bar 25, in the arrangement shown the winding 35 being positioned over and magnetically coupled tightly with the winding 31. The terminal 36 of the winding 35 leads to one side of what may i be termed an output circuit. An auxiliary winding 37 is positioned on the end portion A of the core bar 25 and in the arrangement illustrated the winding 3I is positioned over and magnetically coupled tightly with the winding 28.

A lead 38 connects the winding.37 in series with the winding 35, the lead 39 of the winding 37 forming the other side of the aforesaid output circuit. The winding 35 may be termed an output or load winding and the winding 31 may be considered as an intermediate winding. The closed magnetic circuits described are each provided with a high leakage reactance path between the windings 28 and 37 on the end portion A of the core bar 25 and the windings 31 and 35 on the end portion B of said core bar, which in the arrangement shown comprise the central legs 40 and 41 of the respective E laminations 26 and 27. The shunts 40 and 41 terminate short of the adjacent sides of the core bar 25 thereby providing non-magnetic or air gaps 42 and 43 between the legs 40 and 41 and the core bar 25.

In Figs. 2, 4, 5 and 6 Vo represents the voltage across the output circuit, Vp shows the input voltage on the primary winding, Vs indicates the voltage derived from the winding 16 between the lead 17 and tap IS, and from the winding 35 forming parts of the respective output circuits, and Vpa is the component of the output voltage taken across the terminals of the auxiliary winding 23 or 31, as the case may be.
In Fig. 5, I have shown the vector relations of the various voltages in either arrangement at a certain power output and at different values of primary voltage. The various voltages are either not primed or are primed to correspond to the different values of Vp which is varied. As shown, Vpa is nearly 180* out of phase with Vs, and hence the vectorial sum Vo of the two is approximately their numerical difference.

In Fig. 6, I have illustrated graphically the relation in the constructions described between Vs, Vo, Vpa and Vp ata certain power output.

The principles upon which my improved transformer constructions operate will be clear from a detailed consideration of the construction shown in Figs. 3 and 4. The flux set up by applying a potential across the primary winding 28 will link with winding 31 and cause a definite reactance to be set up by that winding. As the voltage on the. primary winding is increased from zero to a higher level, the flux threading through winding 31 tends to increase in nearly direct proportion to the primary flux, due to the re5 luctance caused by the air gaps 42 and 43, a very slight amount leaking through the shunts 40 and 41. As the Induced E. M. F. reaches a higher value in winding 31 a critical point is reached where resonance takes place, since the reactance of the effective inductance of the winding 31 and the capacity reactance of the condenser 32 are approximately equal at the frequency of the voltage impressed on the winding 28. that is to say.

WCfL where f is the frequency of the voltage impressed on the primary winding 28, L is the effective 70 Inductance of the winding 31, and C is the capacity of the condenser 32. Under this resonant condition, a definite amount of current will flow in the resonant circuit, comprising the winding 31, condenser 32 and leads 33 and 34, and such t6 current will be limited by the constants of that circuit, with the result that a potential will be set up across the winding 31 and a corresponding amount of magnetic flux will be set up in the end portion B of the core bar 25.

It is well known that the inherent characteristic of a resonant circuit is such that its power vector may be many times greater than that of the generator which supplies the energy to the resonant circuit; in this case the energy is supplied by the primary of the transformer to the resonant circuit comprising winding 31 and condenser 32. By varying the primary voltage across winding 28 so that the magnetic density of section A thereof will still remain under the maximum magnetic density of section B of the core, with which the resonant circuit is associated, the change of flux density in section A of the core due to line variation in the primary will have no appreciable effect on the resonant circuit as the reluctance of the leakage path will be under that of section B of the core and flux will leak through the leakage path between the primary and resonant core portions, which leakage path comprises the shunts 40 and 41 and their respective nonmagnetic gap portions 42 and 43. It is due to this leakage reactance path also that the co-efficient of coupling between the primary winding 28 and the aforesaid resonant circuit is reduced to a certain optimum value, thereby maintaining a balanced condition so that the resonant circuit will continue to oscillate with the maximum current therein at a frequency equal to the frequency impressed on the primary winding. Under this state of resonance, winding 31 will set up a magnetic field in the core portion B which will remain practically constant so long as the density in the magnetic field of the core portion A remains at a lower density than that of the core portion B. It follows that this substantially constant field strength in core portion B will produce also a substantially constant voltage across the terminals of winding 31 and condenser 32, and this voltage will remain at practically a constant level regardless of variation of voltage applied to the primary winding 28. The aforesaid resonant circuit, therefore, becomes a constant primary source of voltage for any winding such as the winding 35 that is directly coupled to the winding 31. This coupling can be effected in any desired way, for example, by means of an auto-type transformer arrangement as shown in Fig. 2, or by mounting the winding 35 over the winding 31 as shown in Fig.

4. In the Fig. 4 construction, the output voltage of the windings 35 will also have a practically 5, constant level voltage independent of the voltage variation in the primary winding 28 so long as the circuit which includes the winding 31 remains in resonance.

The auxiliary regulating winding 37 is coupled go to the portion A of the core and is used to change the percentage of regulation of Vo across the terminals 36 and 39 of the output circuit with a variation of Vp. Since this auxiliary winding 37 on core portion A is directly coupled to the pri- 05 mary winding 28, the voltage induced will always be proportional to the turns ratio of primary winding 28 and the auxiliary winding 37.

A very constant level of voltage Vo across the terminals 36 and 39 may be obtained by suitably T0 apportioning the number of turns of said auxiliary winding 37 in relation to the number of turns in the winding 35. Any percentage of regulation of output voltage in relation to variations of Vp also may be obtained from terminals Ts 2 t ist. .y 36 and 39,-for example, an increase in the prinrary voltage on winding 28 will produce a decrease in output voltage Vo by properly arranging or apportioning winding 37 in relation to the winding 35.

The relation of voltages described has been upon the assumption that the transformer is on an open output circuit, that is to say, with no load on the terminals 36 and 39. If a load be applied on said terminals, a magnetic flux in the aforesaid resonant circuit will be developed corresponding to the load on said output circuit thereby unbalancing the magnetic flux in section B of the core. This density change in core section B will in turn affect the stable relation of the flux in core sections A and B and also the leakage reactance through the aforesaid shunt paths thereby causing a greater amount of useful flux from core section A to thread through core section B, which compensates for the energy used by the consuming circuit and at the same time maintains the resonant circuit in the desired oscillating condition.

It will be readily understood that in transformers embodying the principles of my invention the primary winding electrically connected to the source serves to induce voltage to the resonant circuit which is separated from the primary circuit by a high leakage reactance path, thereby providing a low co-efficient of coupling between the primary and the resonant circuits. The aforesaid resonant circuit may be considered as the primary or main source of controlling energy to the winding 35 and hence'to o3 the output or consuming circuit of the transformer.

My improved constant potential transformers are compact and efficient, and are of a small size relative to their power output as compared with other and more cumbersome and expensive apparatus intended for the same purpose. My improved transformers operate at an inherent high power factor, and the output voltage is very close to a pure sine wave.

My improved transformers may be used for many different purposes. They are particularly advantageous in connection with commercial applications such as amplifiers for talking motion pictures, amplifiers for radio transmitters,  Television sets (tubes),   mercury arc lamps, X-ray apparatus, etc.

I wish it to be understood that my invention is not to be limited to the specific constructions shown and described, except so far as the claims may be so limited, as it will be apparent to those skilled in the art that changes in the constructions and arrangements may be made without departing from the principles of my invention.

I claim:1. In a constant potential transformer, the combination of a magnetic core, a winding on said core adapted to be connected to a source of alternating current of fluctuating voltage, a second winding on said core, said core providing a high leakage reactance path for a portion of the flux to thread through one of the windings to the exclusion of the other winding, and means for maintaining the potential across the second winding substantially constant regardless of fluctuations in the input voltage comprising a resonant circuit including said second winding and a condenser, the resonant circuit operating at a frequency equal to the frequency of the voltage impressed on the first winding.
2. In a constant potential transformer, the 7T combination of a magnetic core, a winding on said core adapted to be connected to a source of alternating current of fluctuating voltage, a second winding on said core in spaced relation to said first winding, said core having magnetically disposed between said windings a magnetically 6 permeable shunt with a non-magnetic gap portion, and means for maintaining the potential across the second winding substantially constant regardless of fluctuations in the input voltage comprising a resonant circuit including said second winding and a condenser, the resonant circuit operating at a frequency equal to the frequency of the voltage impressed on the first winding.

3. In a constant potential transformer, the combination of a closed magnetic circuit comprising first and second core portions, a winding on said first core portion adapted to be connected to a source of alternating current of fluctuating voltage, a second winding on said second core portion, said circuit providing a high leakage reactance path for a portion of the flux to thread through one of the windings to the exclusion of the other winding, and means for maintaining the potential across the second winding substantially constant regardless of fluctuations in the input voltage comprising a resonant circuit including said second winding and a condenser, the resonant circuit operating at a frequency equal to the frequency of the voltage impressed on the first winding, the magnetic density at maximum predetermined input voltage of the first core portion being less than the maximum magnetic density of the second core portion.

4. In a constant potential transformer, the 85 combination of a closed magnetic circuit comprising first and second core portions, a winding on said first core portion adapted to be connected to a source of alternating current of fluctuating voltage, a second winding on said second core portion in spaced relation to said first winding, said circuit having magnetically disposed between said windings a magnetically permeable shunt with a non-magnetic gap portion, and means for maintaining the potential across the second winding substantially constant regardless of fluctuations in the input voltage comprising a resonant circuit including said second winding and a condenser, the resonant circuit operating at a frequency equal to the frequency of the voltage impressed on the first winding, the magnetic density at maximum predetermined input voltage of the first core portion being less than the maximum magnetic density of the second core portion.

5. A constant potential transformer comprising in combination a magnetic core, a primary winding on said core adapted to be connected to a source of alternating current of fluctuating voltage, a load winding on said core adapted to be connected to an output circuit, said core providing a high leakage reactance path for a portion of the flux to thread through one of the windings to the exclusion of the other winding, and means for maintaining the potential across the load winding substantially constant regard- 05 less of fluctuations in the input voltage comprising a resonant circuit including a condenser and a third winding, the resonant circuit operating at a frequency equal to the frequency of the voltage impressed on the primary winding, the third winding being in inductive relation to the load winding.

6. A constant potential transformer comprising in combination a magnetic core, a primary winding on said core adapted to be connected to a source of alternating current of fluctuating voltage, a load winding on said core in spaced relation to said primary winding and adapted to be connected to an input circuit, said core having magnetically disposed between said winlings a magnetically permeable shunt with a non-magnetic gap portion.; and means for maintaining the potential across the load winding substantially constant regardless of fluctuations in the input voltage comprising a resonant circuit including a condenser and a third winding, the resonant circuit operating at a frequency equal to the frequency of the voltage impressed on the primary winding, the third winding being in inductive relation to the load winding.

7. A constant potential transformer comprising in combination a closed magnetic circuit comprising first and second core portions, a primary winding on said first core portion adapted to be Sconnected to a source of alternating current of fluctuating voltage, a load winding on said second core portion and adapted to be connected to an output circuit, said magnetic circuit having magnetically disposed between said windings a magnetically permeable shunt with a non-magnetic gap portion, and means for maintaining the potential across the load winding substantially constant regardless of fluctuations in the input voltage comprising a resonant circuit including a conSdenser and a third winding, the resonant circuit operating at a frequency equal to the frequency of the voltage impressed upon the primary winding, the third winding being on the second core portion and in inductive relation to the load winding, the magnetic density at maximum predetermined input voltage of the first core portion being less than the maximum magnetic density of the second core portion.

8. A constant potential transformer comprising in combination a magnetic core, a primary wind40 ing on said core adapted to be connected to a source of alternating current of fluctuating voltage, a load winding on said core adapted to be connected to an output circuit, said core providing a high leakage reactance path for a portion of the 45 flux to thread through one of the windings to the exclusion of the other winding, a resonant circuit including a condenser and a third winding, the resonant circuit operating at a frequency equal to the frequency of the voltage impressed on the 50 primary winding, the third winding being in inductive relation to the load winding, and an auxiliary winding on the core in inductive relation to the primary winding and in series with the load winding, for the purpose described.
55 9. A constant potential transformer comprising in combination a closed magnetic core comprising first and second core portions, a primary winding on said first core portion adapted to be connected to a source of alternating current of fluctuating 60 voltage, a load winding on said second core portion and adapted to be connected to an output circuit, said core having magnetically disposed between said windings a magnetically permeable shunt with a non-magnetic gap portion, a reso65 nant circuit including a condenser and a third winding, the resonant circuit operating at a frequency equal to the frequency of the voltage impressed on the primary winding, the third winding being in inductive relation to the load winding, and an auxiliary winding on said first core portion in inductive relation to the primary winding and in series with the load winding, the magnetic density at maximum predetermined input voltage of said first core portion being less thain the maximum density of said second core portion.

10. A constant potential transformer comprising in combination a magnetic core, a primary winding on said core adapted to be connected to a source of alternating current of fluctuating voltage, a second winding on said core provided with two leads and an intermediate tap, one of said leads and said tap leading to an output circuit, said core providing a high leakage reactance path for a portion of the flux to thread through one of the windings to the exclusion of the other winding, and means for maintaining in said output circuit a substantially constant potential regardless of fluctuations in the input voltage cornprising a resonant circuit including a condenser connected in series between the leads of said second winding, the resonant circuit operating at a frequency equal to the frequency of the voltage impressed on the primary winding.
11. A constant potential transformer comprising in combination a magnetic core; a primary winding on said core adapted to be connected to a source of alternating current of fluctuating voltage; a second winding on said core provided with two leads and an intermediate tap; said core having magnetically disposed between said windings a magnetically permeable shunt with a non-magnetic gap portion; and means for maintaining in said output circuit a substantially constant potential comprising a resonant circuit ineluding a condenser connected in series between the leads of the second winding, the resonant circuit operating at a frequency equal to the frequency of the voltage impressed on the primary winding, and an auxiliary winding on said core in 40 inductive relation to the primary winding and in series with the load winding.
12. A constant potential transformer comprising in combination a closed magnetic core comprising first and second core portions; a primary 45 winding on said first core portion adapted to be connected to a source of alternating current of fluctuating voltage; a second winding on the second core portion and provided with two leads and an intermediate tap; one of said leadsandsaidtap 50 leading to an output circuit; said core having magnetically disposed between said windings a magnetically permeable shunt with a non-magnetic gap portion; the maximum density at maximum predetermined input voltage of said first 55 core portion being less than the maximum density of said second core portion; and means for maintaining in said output circuit a substantially constant potential comprising a resonant circuit including a condenser connected in series between 60 the leads of the second winding, the resonant circuit operating at a frequency equal to the frequency of the voltage impressed on the primary winding, and an auxiliary winding on said core in inductive relation to the primary winding and o5 in series with the load winding.

JOSEPH G. SOLA.

Transformer having constant and harmonic free output voltage

This invention relates to voltage transforming and regulating apparatus, and to core and coil constructions therefor, more particularly to such apparatus having a substantially harmonic free output voltage, and it is an object of the invention to provide improved apparatus and constructions of the character indicated.

It is a further object of the invention to provide improved apparatus of the character indicated having an output voltage which is substantially constant irrespective of variations of input voltage over a certain range, and which is substantially free of harmonics.

It is a further object of the invention to provide an improved transformer.

To provide a source of alternating current voltage of a desired frequency which is free of harmonics, that is, a sine wave, has long been a problem because of the undesired eifects produced thereby. For example, instruments which receive a voltage having harmonics therein may give erroneous and sometimes erratic indications. Apparatus supplied with a voltage having harmonies therein may overheat, and its useful life may be lessened. If the transformer which is supplying a voltage is responsible for the generation of harmonics, the supply transformer as well as the apparatus connected to it may overheat.

Commercial power systems supplying alternating current voltage approach the desired condition of a harmonic free voltage, and a large amount of technical eifort is devoted thereto. However, even with the extensive attention directed to this problem, it frequently occurs, in industrial areas particularly, that the supply voltage has an undesired percentage of harmonics.

In the Patent No. 2,143,745, Joseph G. Sola, entitled Constant Voltage Transformer, there is disclosed and claimed apparatus including a transformer and a condenser wherein a substantially constant output voltage is obtained throughout a certain range of variation in input voltage. While the output voltage of apparatus constructed according to the said patent has good wave form, that is, one largely free of harmonics, under certain conditions the voltage output has included as much as five per cent of third harmonic.

Filter circuits which are connected between the output of a source and a load and which serve to substantially reduce or eliminate harmonics are known. Such filters generally require the use of additional condensers and inductors and will correct the output voltage only when load current is flowing. Moreover, the correction may depend upon the amount of the load, there being the greatest correction at full load and substantially none at no load.

Accordingly, it is a further object of the invention to provide an improved transformer which will provide a constant output voltage substantially free of harmonics, which does not require additional condensers or inductors, and which will substantially eliminate the harmonics from no load to full load.

It is a further object of the invention to provide an improved transformer of the character indicated which will have improved efficiency in operation and which is economical to manufacture.

In carrying out the invention in one form, a transformer is provided having substantially constant output voltage and a substantially harmonic free output voltage and comprising in combination, a core, a primary winding and a secondary winding on the core, a high reluctance shunt magnetically disposed between the primary 2,694,177 Patented Nov. 9, 1954 and secondary windings, a third winding disposed on the core in a position to link with a portion of the leakage flux of the secondary winding and to be substantially free of any linkage with the leakage flux of the primary winding, a condenser which is connected in circuit with the secondary winding and the third winding, the condenser having a value of capacity such that when the transformer is excited with a voltage of predetermined magnitude and frequency a condition of a series resonant nature exists at that frequency, and means for connecting a load circuit to a certain portion of the secondary winding.

For a more complete understanding of the invention, relilferfince should be had to the accompanying drawings in w to Figure 1 is a sectional view of a transformer core and coils according to one form of the invention, and

Figure 2 is a diagrammatic representation of a system according to the invention and employing the core and coils of Fig. 1.

Referring to Figs. 1 and 2 of the drawing, the invention is shown embodied in regulating apparatus including a core and coil arrangement 10 having input, output, regulating and compensating windings and a condenser 11 connected to certain of these windings, all to be more particularly described.

The core and coil arrangement 10 comprises a core 12 which may be made of laminations stamped in the form shown and made of suitable material such, for example, as 26 gauge transformer C steel. The core, as shown, is composed of laminations or layers, each of which consists of two pieces, and when assembled into a stack of desired thickness form an outer piece or shell 13 and a center leg 14. The outer shell includes a pair of end legs 6 and 7 and a pair of side legs 8 and 9. The laminations of center leg 14 may be stamped from the pieces forming the outer shell 13 as part of the same process during which the openings or coil windows 15, 16, 17, 18, 19 and 21 are also formed. A core of the proper thickness is formed by assembling together the required number of outer shell laminations and pressing into the appropriate space the same number of center leg laminations assembled together, as is well understood in this art.

Each lamination of the outer shell 13, as shown, comprises a complete or continuous piece of metal with no joints therein. It will be understood, however, that the same configuration can be made up of individual pieces if so desired. Projecting inwardly from leg 8 between the coil windows 16 and 17 is a member 22 formed of the corresponding parts of the laminations of shell 13, and projecting inwardly from leg 9 between coil windows and 18 is a member 23 also formed of the corresponding parts of the laminations of shell 13. Projecting inwardly between coil windows 17 and 21 is a member 24 formed of parts of the laminations of shell 13, and projecting inwardly between coil windows 18 and 19 is a member 25 also formed of the corresponding parts of the laminations of shell 13. Projecting outwardly from the center leg 14 are members 26 and 27 formed of corresponding parts of the center leg laminations and so disposed as to lie between the coil windows 15 and 18 and 16 and 17 and to be disposed opposite the members 23 and 22, respectively, when the center leg 14 is disposed in shell 13 with the right end thereof forming the joint 28.

The members 22 and 27 are spaced from each other by a nonmagnetic gap 29, and the members 23 and 26 are spaced from each other by a nonmagnetic gap 31. The members 24 and 25 are formed of such a length as to tightly abut the center leg 14 at the joints 32 and 33 and have a cross-sectional area substantially less than that of the end leg 7 of the outer shell 13. The center .leg 14 is formed of a length so as to tightly abut the outer shell at joint 28 at one end and to leave a nonmagnetic gap 35 between the other end of the center leg and the inside surface of end leg 7.

Coil windows 15 and 16 comprise a space within which a primary winding 36 and a compensating winding 37 are disposed; coil windows 17 and 18 form a space within which a secondary winding 38 is disposed;

and coil windows 19 and 21 comprise a space within which a neutralizing winding 3% is disposed. Each of the coils or windings 36, 3'7, 38 and 39 comprise an appropriate number of turns and are provided with sufficient insulation, as is shown schematically in Fig. 1. Each of the coils may be preformed and placed upon the center leg and the unit pressed into the outer shell so as to form the nonmagnetic gap 35 and the abutting joints 23, 32 and 33.

The members 22 and 27 and gap 29, and members 23 and 26 and gap 31, form a high magnetic leakage path between the primary winding 36 and the secondary winding 38. The width of the members 22, 27, 23 and and the length of the nonmagnetic gaps 23 and 31 are chosen so as to provide the desired amount of magnetic leakage reactance, as will become clear subsequently in this specification. While the members 22 and 2'7 and gap 29, and members 23 and 26 and gap 31, as shown, form a high magnetic leakage pathway, it will be understood that the high magnetic leakage pathway may be formed in other well understood manners.

The members 24 and 25, the end of leg 14 together with the end leg 7 and the nonmagnetic gap 35 complete the end path for magnetic flux generated by the primary winding. Since the joints 32 and 33 are press-fits, there is little magnetic reluctance thereat, and consequently the members 24 and 25 form a return path which carries the major portion of the primary flux. These mom bers, however, are formed narrower than the end leg 7 whereby a small percentage of the primary flux flows through the end leg 7. The nonmagnetic gap 35 produces high reluctance in the path of the primary flux, thereby reducing the amount of flux which would flow through leg 7 if the gap were not there, and increasing the percentage of primary flux which flows through members 24 and 25.

The structure as thus far described in Fig. l is illustrated diagrammatically in Fig. 2, the same reference characters being used in the two figures to designate corresponding parts. Thus the windings 36 and 38 are disposed on a common core with a high leakage reactance shunt 22, 27, 29, 23, 26, and 31 disposed therebetween, winding 39 is disposed on the same magnetic core with the nonmagnetic gap 35 separating the core parts, and winding 3'7 is disposed in a closely coupled relationship to winding 36.

The effect of the high leakage path between primary winding 36 and secondary winding 38 is to relatively loosely couple these windings so that each of the windings has a high leakage reactance, and nonmagnetic gap 35 tends to isolate the winding 39 from the flux of the primary winding.

The primary winding 36 is adapted to be connected to a line or source by conductors 41 and 42. The secondary winding 38 has one of its ends connected by means of a conductor 43 to one terminal of condenser ll, and has its other end connected by means of a conductor 44 to one end of neutralizing winding 39 by a conductor 45. The other end of neutralizing winding 3% is connected by means of a conductor 46 to the other terminal of condenser 11. The conductors 44 and 45 connected together may be connected to one side of a load circuit through a conductor 47, and the other side of the load may be connected through a conductor 48 to one end of a compensating winding 37, the other end of which is connected by means of a conductor 49 to a tap on the secondary winding 38. The load circuit may then be traced as follows: From one side of the load through conductor 47, conductor 44, the right-hand portion of winding 38, conductor 49, winding 37, and conductor 43 to the other side of the load.

The operation of the apparatus may perhaps best be understood by considering its operation in two phases; that is, as a constant voltage apparatus alone, and as the combination of the constant voltage and the harmonic elimination or neutralizing apparatus. Considering first the constant potential aspects of the apparatus, it may be made such in one form by removing, in efiect, the neutralizing winding 39. Referring to Fig. 2, this may be accomplished by connecting conductor 46 to conductors 44 and 47 and disconnecting conductor 45 from conductors 44 and 47. When so connected, the apparatus of Figs. 1 and 2 is essentially similar to the form of the apparatus illustrated in the Patent No. 2,143,745, already hereinbefore referred to. When connected in this form as only a constant potential device,

the members 24 and 25, together with leg 7, form a portion of the return circuit for the primary winding flux and provide a return leg having substantially the same elfgctgive cross section as the other flux return legs 8 an For a complete understanding of the operation of the device in this form as a constant voltage transformer, reference may be had to the aforesaid Patent No. 2,143,745. Briefly, however, when voltage above a certain magnitude is applied to the primary winding 36 through conductors 41 and 42, a condition approximating series resonance is set up in the apparatus, and particularly in the circuit including condenser 11 and winding 38. When this condition exists, a substantially constant voltage is obtained across conductors 4'7 and 49 over a wide range of variations in voltage applied to the primary winding. Such small changes as occur in this voltage may be compensated for by the winding 37 which is closely coupled to winding 36 and which is in such a relation as to buck the voltage existing across conductors 47 and 49. Thus, if the primary voltage rises and the output voltage would tend to rise on account thereof, the compensating winding prevents it. Likewise, if the primary voltage falls and the output voltage tends to fall, the bucking voltage is also reduced and the output voltage remains the same. By proper choice of turns of winding 37, the load voltage, that is, the voltage appearing across conductors 47 and 48, is made substantially constant.

Vvhile explanation of the operation of this form of the device as a constant potential apparatus does not lend itself to simple terms, it is thought that the currents flowing in the condenser 11 and winding 38, due to the existing resonance condition, set up a llux condition in the portion of the core underneath and directly associated with the winding 38, due to the presence of the shunts between the primary and secondary windings 36 and 38, such that changes in flux caused by changes in voltage across the primary winding are largely absorbed in the shunts and thus do not change the flux conditions of the secondary winding. The output voltage or" the device as a constant voltage transformer has good wave shape, but it does have appreciable percentages of harmonies in it which are eliminated by the presence of the neutralizing winding 39. When the device is operating as a constant voltage apparatus and the winding 39 is present in the core but is not connected to the circuit, the winding 39 will, of course, have a voltage induced into it since a certain percentage of flux will course through the center leg 14 and through the end leg 7. With the core constructed as shown and described, it has been found that the voltage of coil 3? has a high percentage of odd harmonics in it, that is, third, fifth, seventh and ninth, etc. There is also present a certain value of fundamental since the winding 39 is linked by a small percentage of the flux set up by the primary winding. The presence of the odd harmonic voltages in winding 39 is due to the linkage of winding 39 by the leakage flux created by winding 38 when current flows through the condenser 11 and winding 33. This leakage flux, of course, has two pathways to follow, one of these including a portion of the central leg 14, the members 24 and 25, a portion of the legs 8 and 9 of the core,

. which links with winding 39, that is, that portion of these windings prior to such connection.

the secondary leakage flux which flows across gap 35 and through leg 7. The leakage flux of the primary winding 36 flows largely through the shunts 22, 27, 29 and 23, 26, 31 and thus does not link with winding 39. Consider now the second phase of the device. The winding 39 is connected in circuit with and in additive polarity to winding 38 and with condenser 11 as shown, to form a constant voltage and harmonic free device. When so connected the combined voltage of windings 38 and 39 is increased over the sum of the voltages of With the con nections so made, the percentage of odd harmonics existing in the winding 38 and across the conductors 47 and 49 is very much reduced and a constant voltage output also is had. They are, in fact, reduced to a virtually negligible amplitude. After. the connection has been made, as shown in Fig. 2, the harmonic voltage still '5 exists across winding 39 and also across the condenser 11, but these harmonic voltages are of such phase that they neutralize the harmonics which formerly existed in the Winding 38. For example the third harmonic, which exists in winding 39, is induced therein by the leakage flux from Winding 38, and this harmonic voltage is approximately 180 out of phase with the third harmonic voltage existing in winding 38.

With winding 39 connected into circuit in additive polarity, there has been, in effect, a number of turns added to the secondary winding, but these turns and the core configuration produce harmonic elimination and do not destroy the constant voltage. The flux in the core remains such that the condition of a series resonant nature still exists and hence substantially constant volt age exists across Winding 38. In order to have the proper value of output voltage with the higher voltage available when winding 39 is connected in circuit with winding 38 in additive polarity, the number of turns of winding 38 may be less than in a construction having only constant voltage output of the same value.

The number of turns in winding 39, the cross-sectional area of members 24 and 25, the length of gap 35, and the cross-sectional area of leg 7 enter into the magnitude of the third harmonic voltage produced as compared with the fundamental voltage in winding 39. The fundamental component is not essential since winding 38 may have a sufficicnt number of turns to produce the necessary value thereof, and it is thought that by coupling the winding 39 to the winding 38, as shown, the necessary .third harmonic neutralizing voltage is obtained while at the same time the fundamental voltage is not changed much.

Reduction of the harmonic voltages, and consequently currents in winding 38, reduces the heating of the windings and of the iron thereby making the transformer itself more eificient and economical, this being an advantage in addition to the desirable effects due to the lack of harmonics in loads.

By way of additional and more complete disclosure, one form of apparatus which was constructed and op; erated may be particularly described. This apparatus had a continuous rating of 500 volt amperes, a rated primary (across conductors 41 and 42) voltage range of 90 to 125 volts, a rated load voltage (across conductors 47 and 48) of 115 volts, and a rated load current of 4.35 amperes. In this apparatus the primary winding 36 had 106 turns of No. 13 copper wire arranged in 10 layers of 11 turns per layer, the winding 37 had 12 turns of No. 14 copper wire arranged in one layer of 12 turns, the secondary winding 38 had 405 turns of No. 15 copper wire arranged in 14 layers of 29 turns each, and the winding 39 had 207 turns of No. 15 copper wire arranged in 23 layers of 9 turns each. That portion of winding 38 lying between conductors 44 and 47, that is, the load portion of the winding, had 290 turns arranged in 10 layers.

The core of the apparatus described was designed to operate at a flux density of 100,000 lines per square inch and consisted of a stack of laminations 3 inches thick of No. 26 gauge transformer C steel. The length of side legs 8 and 9 was 6 inches and the length of end legs 6 and 7 was 5 inches; the width of end leg 6 and side legs 8 and 9 adjacent windings 36 and 38 was /8 of an inch; the width of side legs 8 and 9 adjacent winding 39 and the width of end leg 7 was /8 of an inch; the width of members 24 and 25 was A of an inch; the width of center leg 14 inside of coils 36 and 38 and members 24 and 25 was 1% inches, and the width of leg 14 inside of coil 39 was of an inch; the width of shunt members 22, 27, 23 and 26 was /2 of an inch; the length of gaps 29 and 31 was 0.050 of an inch; and the length of gap 35 was 0.150 of an inch. The width of center leg 14 inside of coil 39 may be the same as inside of coil 38 and the number of turns in coil 39 changed to fit the different space of windows 19 and 21.

The condenser 11 had a capacity of 16 microfarads and was rated at 660 volts.

By way of further disclosure, the results of a harmonic analvsis on the foregoing apparatus. as described and particularized, may be summarized. The first analysis was made at no load; that is, there'was no load connected across conductors 47 and 48. The winding 36 was connected to a sine wave generator supplying 115 volts R. M. S. A harmonic analysis of the sine wave generator voltage indicated that 'the voltage supplied to winding 36 had a fundamental component (60 cycles) of arbitrarily assigned amplitude equal to 100 per cent, and a third harmonic of 1.1 per cent of the fundamental, the remaining harmonics being less than one per cent of the fundamental and consequently negligible. With this same connection, the R. M. S. voltage across condenser 11, that is, across combined windings 38 and 39, was 610 volts. The harmonic analysis of this voltage showed on the basis of a fundamental of arbitrarily assigned amplitude equal to per cent, a third harmonic having an amplitude of 7 per cent, and a fifth harmonic having an amplitude of 2 per cent all in terms of the fundamental. The voltage across the winding 39 had an R. M. S. amplitude of 122 volts. The harmonic analysis showed on the basis of a fundamental of arbi trarily assigned amplitude equal to 100 per cent, a third harmonic having an amplitude of 100 per cent, a fifth harmonic having an amplitude of 20 per cent, a seventh harmonic having an amplitude of 4 per cent, and a ninth harmonic having an amplitude of 17 per cent, all in terms of the fundamental. The voltage across winding 38 had an R. M. S. amplitude of 522 volts, the harmonic analysis showing on the basis of a fundamental of arbitrarily assigned amplitude equal to 100 per cent, a third harmonic having an amplitude of 1.1 per cent, a seventh harmonic having an amplitude of l per cent, and a ninth harmonic having an amplitude of 1.8 per cent, all in terms of the fundamental. Correspondingly, the voltage across that portion of winding 38 between conductors 44 and 49 (load winding) had an R. M. S. amplitude of 127 volts, the harmonic analysis showing on the basis of a fundamental of arbitrarily assigned amplitude equal to 100 per cent, a third harmonic having an amplitude of .4 per cent, a fifth harmonic having an amplitude of .6 per cent, a seventh harmonic having an amplitude of 1.2 per cent, and a ninth harmonic having an amplitude of 1.6 per cent, all in terms of the fundamental. The output voltage, that is, the voltage across conductors 47 and 48, had an R. M. S. value of 114 volts with the harmonic analysis showing on the basis of an arbitrarily assigned fundamental component having an amplitude equal to 100 per cent, a third harmonic having an amplitude of .4 per cent, a fifth harmonic having an amplitude of .7 per cent, a seventh harmonic having an amplitude of 1.3 per cent, and a ninth harmonic having an amplitude of 1.7 per cent, all in terms of the fundamental.

The percentage of harmonics at the load conductors 47 and 48 is of the same general order as that of the applied voltage, the third harmonic being an improvement and some of the higher harmonics being very slightly increased.

In the apparatus as described and for the harmonic values given, when the conductor 46 was connected to the conductor 44, that is, the winding 39 was removed from the circuit as previously described, and the same sine wave generator was connected to the winding 36, the voltage across winding 36 had an R. M. S. amplitude of 115 volts. A harmonic analysis thereof showed on the basis of a 6D cycle or fundamental component arbitrarily assigned an amplitude of 100 per cent, a third harmonic having an amplitude of .8 per cent, a fifth harmonic having an amplitude of .4 per cent, and a seventh harmonic having an amplitude of .3 per cent, all in terms of the fundamental. The voltage across condenser 11 or across winding 38 had an R. M. S. amplitude of 467 volts, the harmonic analysis showing on the basis of a fundamental component of 100 per cent, a third harmonic having an amplitude of 23 per cent, and a fifth harmonic having an amplitude of 6 per cent, all in terms of the fundamental. The portion of winding 38 forming the load winding, that is, the winding connected across conductors 47 and 49, had an R. M. S. amplitude of 113 volts, the harmonic analysis showing on the basis of a fundamental component arbitrarily assigned an amplitude of 100 per cent, a third harmonic having an amplitude of 23 per cent, and a fifth harmonic having an amplitude of 6 per cent, all in terms of the fundamental. Under these conditions, the output voltage, that is, across conductors 47 and 48, had an R. M. S. amplitude of 100 volts, the harmonic analysis showing on the basis of a fundamental component arbitrarily assigned an amplitude of 100 per cent, a third harmonic having an amplitude of 27 per cent, a fifth harmonic having an amplitude of 7 per cent, and a seventh harmonic having an amplitude of one per cent, all in terms of the fundamental. The voltage across winding 39 had an R. M. S. amplitude of 73 volts, a harmonic analysis showing on he basis-of a fundamental componen arbitrarily assignedau amplitude f 100. per cent. a-third harmonic havin an amplitude of 11.00, per cent, a fifth harmoni havingan amplitudeof .78 per cent, a sev nth harmonic having an amplitude; of percent, an a ninth harmonic having an amplitude'of 6 per cenhall in terms of the fundamental.

A compari n f he rela ive harmonic val es across conductors a7 and 43 with the condenser c nnected to include the winding 39 andto exclude it, reveals. the reduction in the harmonic content' t? he output vol age.

A m lar h rmonic a alysis was. made with the apparatus opera ng at full loa with th sin wavesource as alr adyescrib providing l.15 volts acros he primary winding 36. With, the condenser 11 connected s shown in F gthe output volt ge across conductors 47 and cent, a third harmonic having an amplitude of 1-1 per cent, a fifth harmonic having an arriplittldev of .4 per cent, a seventh harmonic having an amplitude of 1.6 percent, an a ni th h rmonic having an amplitude of 1.2 p r. cent. These harmonic values are not substa tially diiferent from those taken at no load. Under the full load condition described, the voltage across winding 3,9had an R. M. S. amplitude of 111 volts, the harmonic analysis showing on the basis of a fundamental component arbitrarily assigned an ampltiude of 100 per cent, a third harmonic-having an amplitude of ,98 per cent, a fifthv harmonic having an amplitude of 16 per cent, a seventh harmonic having an amplitude of ll per cent, and a ninth harmonic having an amplitude of 11 per cent, all in terms of thefundamental- The vol age across Condenser 11 had an R. M. S. value of 593 volts with the harmonic analysisshowing n the basis of a fundamental component arbitrarily assigned an amplitude of 100 per cent, a third harmonic having an amplitude of 13 per cent, a fifth harmonic having an amplitude of 1.5 per cent, a seventh harmonic having an amplitude of .2 per cent, and a ninth harmonic having an amplitude of .1 per cent, all in terms of the fundamental. The voltage across winding 38'had an R. M. S. amplitude of 512 volts, the harmonic analysis show ing a fundamental component arbitrarily assigned an amplitude of 100 per cent, a third harmonichaving an amplitude of 1.7 per cent, a fifth harmonic having an amplitude of zero per cent, a seventh harmonic having an am.- plitude of 1.4 per cent, and a ninth harmonic having an amplitude of 1.2 per cent.

With full load being supplied by the transformer, and i with the condenser 11 connected so as to-remove wind.- ing .39 from the circuit,-tha.t is, conductor connected to conductor 44, the output voltage across conductors 4.7. and 48 had an R. M. S. amplitude of '97 volts, the harmonic analysis showing on the basis of a fundamental component arbitrarily assigned an amplitude of 10.0 per cent, a third harmonic having an amplitude of 23 per cent, a fifth harmonic having an amplitude of 6 per cent, and a seventh harmonic haying'an amplitude of .Tper cent. The voltage of winding 3.8 or condenser 11 had an, R. M. ,S. amplitude of 452 volts, the harmonic analysis showing a fundamental component arbitrarily assigned an amplitude of .100 per cent, a third harmonic having an amplitude of '20 per cent, a fifth harmonic having ah amplitude of per cent, and a seventh harmonichaving an amplitude of ,4 per cent. Comparing the relativeharlmonic value between the-full load condition where-in the neutralizing winding 39 is connected into and out .of the circuit, reveals that the harmonic content is very much by the presence of winding 39 in the core structure defined.

The loads fed by the transformer in the preceding tests were resistance loads.

"The structure as shown in Fig. 2 and having the harmonic analysis as given, was connected to a re ular The. in en on ha ing h s be descr ed, Wha is el imedandde re to. be s cur d by L e s. a nt s:

A transformer having substantially costant output voltage and a substantially armonic free voltage comprising, a core, a primary winding and a secondary winding on said core, ahigh reluctance shunt magnetrc l v disposed t eens d v nd ngs, a con e av ng a value of capacity such that when'connected across said secondary winding and the transformer is excited with a voltage of predetermined magnitude and frequency a condition of a seriesresonaut nature exists at the said freq v, a third ind ng d pos d n sa d ore n a P tion to link with a portion ofthe leakage flux of said secondary Windingand to be substantially free of any linkage with the leakage flux of said primary winding, said secondary winding, said third winding and said condenser being connected in circuit, and means for connecting a load circuit to at least a certain portion of said secondary winding.

2. A transformer having substantially constant output voltage and a substantially harmonic free output voltage comprising, a core, a primary winding and a secondary winding on said core, a high reluctance shunt magnetically disposed between said windings, a condenser having a value of capacity such that when connected across said secondary winding and the transformer is excited with a voltage of predetermined magnitude and frequency a condition of a series resonant nature exists at the said frequency, a third winding disposed on said core in a positionto link with a portion of the leakage flux of said secondary windingand to be substantially free of any linkage with the leakage flux of said primary winding, said secondary winding, said third winding and said condenser being connected in circuit with said third winding in additive polarity to said secondary winding, a compensating winding disposed on said core in close coupled relationship with said primary winding and connected in b ng r lat onship to saidse ary nd ng. and means for connecting a load circuit to at least a certain portion of said secondary winding and to said compensating winding,

A ns m ha ing suhstantia yc nst toutput voltage and a substantially harmonic free output voltage comprising, a core, a primary winding and a secondary winding on said core, a high reluctance shunt magnetically disposed-between said windings, a condenser having a value of capacity such that when connected across said secondary winding and the transformer is excited with a voltage of predetermined magnitude and frequency a condition-of a series resonant nature exists at the said frequency, a harmonic eliminating winding disposed on said core in a position to link with a portion of the leakage flux'of said secondary winding and to be substantially free of any linkage with the leakage flux of said primary winding, said secondary winding, said harmonic eliminating winding and said condenser being connected in circuit, and means for connecting a load circuit to at least a certain portion of said secondary winding.

4. A transformer having substantially constant output voltage and a substantially harmonic free output voltage comprising, a core, a primary winding and a secondary winding on said core, a high reluctance shunt magnetically disposed between said windings, a condenser having a value of capacity such that when connected across said secondarywinding and the transformer is excited with a voltage of predetermined magnitude and frequency a condition of a series resonant nature exists at the-said frequency, a third w'mding disposed on said core in a position to link with a portion of the leakage flux of said secondary winding and to be substantially free of any linkage with the leakage flux of said primary winding, saidse'condary winding, saidthird winding and said condenser being connected in a series circuit with said third winding in additive polarity relative to said secondary winding, and means for connecting a load circuit to at least a certain portion .of said secondary winding.

5- A n o m h in subs ant ally con tant ou pu voltage an a substanti l y harmonic free output lt ge mpr sing, a c e, a pr ary Winding and a se nd ry in g o said co e, a hi h re uct n s un ma c ly d posed be ween a d i di s, .a cond se having a alu o apac y such t a h n e ted a r ss sai se da y in ing. and he t an former is excited with a voltage of predetermined magnitude and frequency a condition of a series resonant nature exists at the said frequency, a thir:l winding disposed on said core, the leakage flux path of said third winding including a portion having low reluctance and a portion having high reluctance to the fluxes of said primary and secondary windings, said secondary winding, said third winding and said condenser being connected in circuit, and means for connecting a load circuit to at least a certain portion of said secondary winding.

6. A transformer having substantially constant output voltage and a substantially harmonic free output voltage comprising, a core, a primary winding and a secondary winding on said core, a high reluctance shunt magnetically disposed between said windings, a condenser having a value of capacity such that when connected across said secondary winding and the transformer is excited with a voltage of predetermined magnitude and frequency a condition of a series resonant nature exists at the said frequency, a third winding on said core, a low reluctance shunt magnetically disposed between said third winding and said primary and secondary windings, and high reluctance means disposed in the flux path of said third winding, said secondary winding, said third winding and said condenser being connected in circuit, and means for connecting a load circuit to at least a certain portion of said secondary winding.

7. A transformer having substantially constant output voltage and a substantially harmonic free output voltage comprising, a core, a primary winding disposed on one leg of said core, a secondary winding disposed on said one leg, said primary and secondary windings being relatively loosely coupled thereby to provide said windings with high leakage reactance, a condenser having a value of capacity such that when connected across said secondary winding and the transformer is excited with a voltage of predetermined magnitude and frequency a condition of a series resonant nature exists at the said frequency, a third winding on said one leg, at low reluctance shunt disposed between said third winding and said secondary winding, high reluctance means in said core beyond said shunt, and means for connecting a load circuit to at least a certain portion of said secondary winding.

8. A transformer having substantially constant output voltage and a substantially harmonic free output voltage comprising, a core, a primary winding disposed on one leg of said core, a secondary winding disposed on said one leg, said primary and secondary windings being relatively loosely coupled thereby to provide said windings with high leakage reactance, a condenser having a value of capacity such that when connected across said secondary winding and the transformer is excited with a voltage of predetermined magnitude and frequency a condition of a series resonant nature exists at the said frequency, a third winding on said one leg, a low reluctance shunt disposed between said third winding and said secondary winding, high reluctance means in said one leg beyond said shunt, and means for connecting a load circuit to at least a certain portion of said secondary winding.

9. A transformer having substantially constant output voltage and a substantially harmonic free output voltage comprising, a core, a primary winding disposed on one leg of said core, a secondary winding disposed on said one leg, said primary and secondary windings being relatively loosely coupled thereby to provide said windings with high leakage reactance, said high leakage reactance means including a magnetic shunt having a nonmagnetic gap, a condenser having a value of capacity such that when connected across said secondary winding and the transformer is excited with a voltage of predetermined magnitude and frequency a condition of a series resonant nature exists at the said frequency, a third winding on said one leg, a low reluctance shunt disposed between said third winding and said secondary winding, high reluctance means in said core beyond said shunt, said high reluctance means including a core portion and a nonmagnetic gap, and means for connecting a load circuit to at least a certain portion of said secondary winding.

10. A transformer having substantially constant output voltage and a substantially harmonic free output voltage comprising, a core, a primary winding and a secondary winding on said core, a high reluctance shunt magnetically disposed between said windings, a third winding disposed on said core in a position to link With a portion of the leakage flux of said secondary winding and to be substantially free of any linkage with the leakage flux of said primary winding, a condenser, said secondary winding, said third winding and said condenser being connected in circuit, said condenser having a value of capacity such that when the transformer is excited with a voltage of predetermined magnitude and frequency a condition of a series resonant nature exists at the said frequency, and means for connecting a load circuit to at least a certain portion of said secondary winding.

ll. A transformer having substantially constant output voltage and a substantially harmonic free output voltage comprising, a core, a primary winding and a secondary winding on said core, a high reluctance shunt magnetically disposed between said windings, a third winding disposed on said core in a position to link with a portion of the leakage flux of said secondary winding and to be substantially free of any linkage with the leakage flux of said primary winding, a condenser, said third winding in additive polarity to said secondary winding and said condenser being connected in circuit with said secondary winding, said condenser having a value of capacity such that when the transformer is excited with a voltage of predetermined magnitude and frequency a condition of a series resonant nature exists at the said frequency, and means for connecting a load circuit to at least a certain portion of said secondary winding.

12. A transformer having substantially constant output voltage and a substantially harmonic free output voltage comprising, a core, a primary winding and a secondary winding on said core and having high leakage reactance associated therewith, a condenser having value of capacity such that when connected across said secondary winding and the transformer is excited with a voltage of predetermined magnitude and frequency a condition of a series resonant nature exists at the said frequency, a third winding disposed on said core in a position to link with a portion of the leakage flux of said secondary winding and to be substantially free of any linkage with the leakage flux of said primary winding, said secondary winding, said third winding and said condenser being connected in a series circuit with said third winding in additive polarity relative to said secondary winding, and means for connecting a load circuit to at least a certain portion of said secondary winding.

13. A transformer having substantially constant output voltage and a substantially harmonic free output voltage comprising, a core, a primary winding and a secondary Winding on said core, said primary and secondary windings being relatively loosely coupled thereby to provide said windings with high leakage reactance, a condenser having a value of capacity such that when connected across said secondary winding and the transformer is excited with a voltage of predetermined magnitude and frequency a condition of a series resonant nature exists at the said frequency, a third winding disposed on said core in a position to link with a portion of the leakage flux of said secondary winding and to be substantially free of any linkage with the leakage flux of said primary winding, said secondary winding, said third Winding and said condenser being connected in circuit with said third winding in additive polarity to said secondary winding, and means for connecting a load circuit to at least a certain portion of said secondary winding.

14. A transformer having substantially constant output voltage and a substantially harmonic free output voltage comprising, a core, a primary winding and a secondary winding on said core, said primary and secondary windings being relatively loosely coupled thereby to provide said windings with high leakage reactance, a condenser having a value of capacity such that when connected across said secondary winding and the transformer is excited with a voltage of predetermined magnitude and frequency a condition of a series resonant nature exists at the said frequency, a third winding disposed on said core in a position to link with a portion of the leakage flux of said secondary winding and to be substantially free of any linkage with the leakage flux of said primary winding, said secondary winding, said third winding and said condenser being connected in circuit with said third winding in additive polarity to 11 said secondary Winding, a compensating winding disposed on said core in close coupled relationship with said primary winding and Connected in bucking relationship to said secondary winding, and means for connecting a load circuit to at least a certain portion of said secondary Winding and to said compensating Winding.