Патент USA US2412291код для вставки
Dec. 10, 1946. - _o,- H.-SCHADE 2,412,291 ELECTRON. DISCHARGEv DEVICE Filed May 30, 1942_ 3 Sheets-Sheet 1' *JAl IMIEOF E0707?” 2 3nocntor By Dec. 10, 1946. -o. H. SCHADE - 2,412,291 ELECTRON DISCHARGE DEVICE Filed may’ 30, 1942 " _ 3 Sheets-Sheet 2 > ‘ Dec. 10, 1946. v o. H. SCHADE 2,412,291 ELECTRON DISCHARGE DEVICE Filed May 30, 1942 3 Shee'ts-Sheet 3 Snventor attorney 2,412,291 Patented Dec. 10,__194$ ‘in T "E E S 2,412,291 ELECTRON mscnAnoE nEvrcE Otto H. Schade, West Caldwell, N. J., asslgnor to Radio Corporation of America, a corporation of Delaware Application May 30. 1942, Serial No. 445,185 8 Claims. (01. 315-44) 1 ' This invention relates to de?ection circuits for 2 rotation of a unidirectional de?ecting ?eld; Fig. cathode ray indicating systems, and more par- , 3 is a circuit diagram showing one form of this ticularly to circuits for producing linear radial invention; Figs. 4a, 4b, 4c, 4d, 4e and Figs. 5a, traces on the ?uorescent screen of a cathode ray 5b, 5c, 5d, 5e, 5)‘, 5g and 5h are graphs represent ing wave forms of voltages produced in operation to a trace having one of its ends at or near the of the device of the invention; Figs. 6, '7, 8, 9 and center of the cathode ray tube screen, as .10 are schematic diagrams of modi?ed de?ection distinguished from a “diametral trace,” having voltage ampli?er and D.-C. insertion circuits; its ends approximately equidistant from the cen Fig. 11 is a diagram of a circuit for the ‘use of ter of the screen. In certain applications of cath 10 modulated sine wave, instead of sawtooth, de ode ray tubes, as in some types of radio distance ?ecting voltages; Figs. 12a and 12b are graphs of tube. The words “radial trace” are used to refer and direction indicators, it is desirable to pro duce a radial trace which is rotatable about its inner end to correspond in direction with the an gular position of a remote shaft, which, for ex wave forms illustrating sawtooth wave distortion and its compensation; and Figs. 13a, 13b and 130 are graphs of three sawtooth waves having the 15 ample, may be connected to a rotatable direc tional antenna. The problem is complicated by the fact that the remote control shaft need not necessarily rotate at a constant speed, but may be stopped and reversed. a The conventional de?ection means in a cath ode ray tube is a stationary four-pole system con same amplitude and repetition time but different slopes. - Referring to Fig. 1, the voltage characteristics i, 2, 3, a required at each of the plates of an electrostatic de?ection system to produce radial de?ection are applied to the de?ecting plates D1, D2, D3 and D4. Similarly, as shown in Fig. 2, the currents 6 and ‘I may be supplied to the de ?ecting coils M in a magnetic de?ection system. plates for electrostatic de?ection or two pairs of For a QQnstant angular velocity, the modulation de?ection coils arranged at right angles for mag 25 envelope is sinusoidal and the average component netic de?ection. According to this invention, the is zero. For a stationary trace 5 at any position, line of de?ection of the beam in a cathode ray such as indicated by the angle or, the average sisting of four rectangularly disppsed de?ection tube is rotated about one of its ends at the axis of the tube by impressing upon each of the beam component has a ?nite value and a polarity de pending on the value of a, as shown by the de?ecting means a sawtooth wave or other sweep 30 dashed curves. signal of sinusoidally varying amplitude. The sinusoidal variations on one pair of the beam de ?ecting means differ in phase by 90° from the variations on the other pair. The principal object of this invention is to pro vide an improved method of and means for de ?ecting a cathode ray beam. Another object of , . For any radial trace other than one rotating at a constant velocity the average component is not zero. Therefore, conductive coupling or its equivalent between signal' generating and de ?eeting systems is essential. A system for radial de?ection and variable angular velocities include ing zero value is thus substantially di?erent in‘ this invention is to provide improved means for operation and organization from a system with generating signals for radial de?ection of a cath constant velocity of ?eld rotation and diametral ode ray beam, said signals being controlled in am 40 de?ection. A diametral system termed “a radial plitude in accordance with the angular position scanning system” in the De Forest ‘Patent of the rotor of a remote control unit so as to pro 2,241,809, makes no provision for transmission duce a synchronous angular displacement of the of average values other than zero.’ A circuit ‘for. radial cathode ray beam trace. A further object generating and modulating saw-toothfvoltages as is to provide an improved system of the described ' ‘ shown in Fig. 1 is illustrated in detail'in Fig. 3. type in which the length of the radial trace is A multivibrator i0 has its output connected constant throughout a 360° rotation independent across a’ capacitor -9. This circuit is described of the speed of rotation. Other objects, features and claimed in U. S. Patent No. 2,157,434 to James and advantages of this invention will be appar L. Potter. A capacitive voltagedividerii is also ent to those "skilled in the art upon consideration 50 connected across the capacitor 9 and comprises of the following speci?cation with reference to four ?xed capacitors l3, l5, l1 and i9 and a vari the accompanying drawings, in which Figs. 1 and able capa-citor 2|. The rotor of the capacitor 2| 2 are graphs representing the wave forms of volt ‘is mechanically connected to the shaft' (not ages or currents required in electrostatic or mag shown) with which the radial trace is to be syn netic .de?ection systems respectively to produce 55 chronized. The plates of the capacitor 2| are 9,412,291 . 4 ' ‘ . at 34, due to the fact that the average com shaped so that the voltages across the ?xed ca ponent, shown by the dashed line, is of too low a pacitors have envelopes which are half wave frequency to be transmitted. If the voltage 34 sinusoidal functions of the angular position a and the corresponding quadrature voltage 33 of the rotor, plus a residual component due to the minimum capacitance between the rotor and Cl were applied to the power ampli?er and de?ect ing circuit, each trace of the cathode ray would stator plates. The voltages l4, l6, l3 and 23 on have its center at the center of the pattern, the ?xed capacitors I3, l5, l1 and [9 respectively of the voltage divider as functions of the posi instead of starting at the center. As the capacitor 2| is rotated slowly, the trace would rotate about tion of the rotor of the capacitor 2| are illus trated by the correspondinglynumbered curves in Fig. 3. The capacitor I‘! is coupled to the in put of an ampli?er tube 25, and the capacitor l3, connected to the opposite stator plate of the ca pacitor 2 I, is coupled through a polarity reversing its center instead of around one of its ends. The D.-C. insertion circuit, or "clamping” cir cuit operates to restore the lost average com ponent of the modulated sawtooth wave. The grid of the power tube 33 is connected through a tube 21 to the input of an ampli?er tube 29_.~ The 15 pair of diodes 46 and 48 and a tapped resistor 53 to a bias source 55. A tube 49 is provided with plate and cathode load resistors 51 and 53, re The capacitors l5 and I9, which are connected "tubes 25 and 29 have a common plate circuit 3|. ' to the other pair of oppositely disposed stator plates of the capacitor 2|, are coupled similarly to a pair ofampli?ers with a common load circuit. These circuits are omitted from the drawing for clarity. I ‘ . Tile plate circuit 3| is coupled to the grid of a power ampli?er tube '33 through a capacitor 35. spectively, coupled through capacitors BI and 83, respectively, to the diodes 46 and 48, which are connected to conduct in opposite directions. The grid of the tube 49 is coupled to receive impulses 65 from the multivibrator l0 during the return period of the sawtooth wave. This signal results in .a positive pulse at the cathode and a negative The plate circuit of the tube 33 includes one pair 25 ‘pulse at the plate of the tube 43, causing both diodes 46 and 48 to conduct, momentarily present ing a relatively low impedance path from the grid of the tube 33 to the resistor 53 and thence to the bias source 55 which is adjusted to provide the and are ‘connected to provide a constant current 43 through the de?ecting coils M to cancel the 30 proper grid voltage for the tube 33 at the start of the sawtooth voltage. The tap on the resistor zero-signal component 35 of the plate current 53 is adjusted to form a‘balanced bridge circuit of: the tube 33. An auxiliary circuit including with the impedances of the diodes 48 and 48, pre tubes 41 and 49 is connected to thegrid of the venting the pulses 65 from reaching the grid of the power tube 33 in order to restore the direct cur rent component of the signal lost in the capaci 35 tube 33. During the pulse time of pulses 35, of the de?ecting coils M of a cathode ray tube. Resistors'3land 39 and a screen grid tube 4| are also included in the plate circuit of the tube 33 ' tively coupled ampli?ers 25, 21 and 29. ‘ The operation is as follows: The multivibrator IO produces a sawtooth shaped voltage wave 8 on corresponding to the sawtooth return period, the ‘ ‘coupling capacitor 35 is discharged rapidly to the potential existing at that time between D.-C. voltage 55 and the plate of the preceding stage. the capacitor 9. The sawtooth frequency is con trolled by the circuit constants of themultivibrator 40 The capacitor 35 maintains this potential for one sawtooth period during which the diodes 46' and and may be synchronized with a signal applied to 48 are non-conducting and act as open circuits, the input 5|. The voltage 8 is applied to the capacitive voltage divider ll‘, resulting voltages and is then reset again in the same manner, thus causing all sawtooth cycles to begin with the l4, I6, l8 and 20 on the corresponding capacitors. The voltage i8 is ampli?ed by the tube 25, and the 45 same voltage, that of the source 55. The signal at the grid of the tube 33 is hence undistorted voltage l4, which has a sinusoidal envelope com as compared with the voltage 32 although the ponent 180° out of phase with that 'of the voltage ampli?er coupling networks do not pass low or “5, is reversed in polarity by the tube 21, and zero frequencies, but only the frequencies needed ampli?ed by the tube 29. ‘The two ampli?ed voltages are combined in the common plate cir 50 for transmission of the sawtooth wave 8. AIM ther advantage in the use of a clamping circuit cuit 3 I, cancelling the residual components caused is the elimination of extraneous low frequency by the minimum capacitances of the capacitor ‘2| ' pickup voltages, such as 60 cycle hum which may and adding alternately reversed half-sinusolds occur in the grid circuits of the tubes 25 and 21. to produce a voltage wave 32.. This is ampli?ed For symmetrical electrostatic de?ection cir by the power tube 33 to provide a similarly , cuits, four voltages are needed as shown in Fig. shaped current wave in the de?ecting coils M. l; the voltages 2 and 4 are obtained by inverting In the same manner, the voltages l6 and 20 across the phase of the voltages | and 3 respectively in a the capacitors l5 and I9 are amplified and com bined to produce a current wave like the voltage conventional phase inverter circuit. This may 36 in a second pair of de?ecting coils, which are 60 be done before the clamping, to allow capacitive spaced 90° around the axis of the cathode ray tube coupling 0! the phase inverters. Each de?ection plate of the cathode ray tube is then directly’ from the ?rst pair. . _' coupled to one power ampli?er tube having a "Since the voltages 32 and 36 have sinusoidal envelopes-90° out of phase, they will produce the clamping circuit in its grid circuit. required rotating radial sweep, de?ecting the 65 The de?ection circuits can‘ be simpli?ed by combining the halves of each sinusoidal modula cathode ray beam outward from the center at the tion envelope after D.-C. restoration. The volt sawtooth frequency and rotating the resultant ages appearing at the respective output termi radial trace about its inner end at the envelope nals of a capacitive voltage divider connected to a frequency, which is 'the frequency of rotation of thevariable capacitor 2|. However, this is true 70 sawtooth wave source as in Fig. 3 are illustrated in Figs. 5a, 5b, 5c and 5d. Upon passing through capacitively coupled ampli?ers, the direct com ponents of these voltages are lost, resulting in the and~29 to pass it without attenuation. When the waves shown in Figs. 5e‘, 5]‘. 50 and 5h, respec speed of rotation of the capacitor 2| is lower, the voltageacrossthe load-3| assumes the form shown 75 tively. The sawtooth components are in phase onlyif the envelope frequency is high enough for. the capacitively coupled ampli?ers 25, 21 5 aaiaaei ‘in the waves 5e and 5!, which represent the two power factor. This condition is secured by mak ing the reactances of the transformers H1 and I I9 large in comparison to the total resistance in halves of one sinusoidally modulated de?ection voltage, and in the waves 5g and 5h, which rep resent the other deflection voltage, modulated in the circuit, including the diode resistance. Be quadrature phase with the ?rst. Referring to Fig. 6, a circuit for one of the phases for a single . plate of the "electrostatic de?ection system is shown. The voltages corresponding to one phase, for example those of Figs. 5e and 5f, are applied to the terminals 62 and 54, respectively. The polarity of the sawtooth component of the cause of this reactance, the diodes become con ducting at the start of the sawtooth cycle, main taining a closed circuit for substantially the en tire cycle. This action is similar to that of a half wave recti?er circuit of low resistance con 10 nected to a sine wave generator as illustrated in . wave 5f is reversed by a phase inverter 65 and ap plied to an output tube 61, while the wave 5c is applied directly to an output tube 69. Diodes ‘H and 13 are connected in the grid circuits of the ‘ tubes 61 and 69, and act as peak recti?ers, pro ducing D.-C. voltages which are proportional to ' the average components of the sawtooth waves and are added to them, thus restoring the wave Fig. 4a. Figs. 4b and 40 show graphic construc tions of the transient operation of such a circuit under high and low power factor conditi'ons re-v spectively. The wave forms e and 2' would be obtained if the diode were short-circuited. The transient voltages t arising when the diode starts to conduct (when e=0) are added graphically. When t‘=e, at the time s, the diode stops conduct ing. When the power factor is zero, the conduc envelopes to the shapes shown in Figs. 5a and 5b. 20 tion time is‘ one full cycle, and when the power ‘ These are combined in the common plate circuit of the tubes 61 and 69, resulting in a voltage wave factor is unity, the conduction time is one-half . cycle. The current in a low power factor circuit like that shown in Fig. 1a, which is applied di with a diode is hence unidirectional, but'of sub rectly to a de?ection plate 15 of a cathode ray tube 11. The other de?ection plate 19 is supplied with a voltage similarly derived from the waves 5g and 5h. .Fig. 8 shows a circuit for one of the two phase connections for a push-pull or symmetrical elec trostatic de?ection‘ system. The half wave com ponents, such as those shown in Figs. 5c and 5,‘, are applied to the terminals 8! and 83, which are connected to the grids of a pair of ampli?er tubes 85 and 81, respectively. The plates of the tubes 85 and 81 are coupled to the grids of a pair stantially. the same wave form as without the diode. The D.-C. polarity depends on the polar ity of the diode. - This action is used in the cir cuit of Fig. '7 to restore the D.-_C. component of the unidirectional deflection current, producing de?ection positions shown in Figs. 4d and 4e by the traces I21 and I29 with respect to the center of a cathode ray tube I3I. A choke coupled, so called direct drive circuit is shown in Fig. 9. Its operation is similar to that of the circuit of Fig. 7. A pair of power ?ecting plates 93 and 95 of a cathode ray tube tubes_II3 and H5 are coupled to the de?ecting coils I25 by means of chokes I33 and I35 and capacitors I31. The tubes H3 and H5 are oper-. ated class A, and the input to the tube H5 is re 91. versed in phase by an inverter I39. of power ampli?er tubes 89 and 9I, respectively, whose plates are connected to one pair of de The power tubes 89 and 9! have a common cathode resistor 99, which is relatively high in resistance as compared to the reciprocal of the transconductance of the tubes 89 and 9| so as Practical sawtooth de?ection circuits, partic ularly when operated at low frequencies, may cause distortion‘ of the current wave form because of to produce phase inversion by cathode coupling. insu?icient reactance, resulting ‘in a rapidly de A pair of diodes IM and I03 are connected as peak recti?ers in the grid circuits of the power caying wave form as illustrated in Fig. 12a. This is corrected by distorting the driving voltage by an equivalent amount as shown in Fig. 12b. This tubes, and function like. the diodes “II and 13 in correction may be obtained automatically by the the circuit of Fig. 6. Since the diodes are not use of inverse'feedback‘. The voltage drops on 100 percent efficient, they do not supply quite resistors IM and I43 are taken oil on leads I85 enough D.-C. voltage to restore the average value of the sawtooth waves, and the de?ections of the 50 and I41 and added to the sawtooth signal in the , proper polarities in earlier stages of the ampli?er beam in the tube 91 tend to start slightly off cen system. ter. This is compensated by reducing the A.-C. The circuit shown in Fig. 10 is arranged to components by the same percentage. A tap I05 permit operation with di?erent ratios of current on each of the load resistors I01 of the ampli?ers transformation for e'?icient operation with widely 85 and 81 is coupled through a capacitor I09 to different sawtooth slopes as shown in Figs, 13a, the power tube grid circuit. Resistors III are 13b and 130. The high slope, short duration provided for isolating this circuit from the peak sawtooth I30 limits the permissible inductance of recti?ers I III and I03, so that the A.-C. voltage the de?ection coils I53 to a relatively low value, drops on the resistors II I will be subtracted from 60 because the inductive voltage the A.-C. voltages across the recti?ers. Circuits for magnetic de?ection in which alter nate half wave signals are combined after am pli?cation and D.—C. restoration are shown in ' ' Fig. 7. Referring to Fig. 7, a pair of power am pli?er tubes II 3 and H5 are arranged to have voltage waves like those shown in Figs. 5c and 5]’ applied to their ‘respective control grids, and their plate circuits include the primaries of a pair of transformers H1 and H9, respectively. The La is limited by the available plate supply voltage, thus requiring a high current for a given de?ec tion. The average plate current and power dis sipation of the tube I5I is, however, moderate be cause of the long zero current time interval be tween de?ection time repetitions. For this signal no step down is used, and a switch I55 is op transformer secondaries are connected through 70 erated to contact point I51, connecting the de-, diodes l2l and I23 to one pair of de?ection coils ?ection circuit to the primary of the transformer I25, so that current will ?ow in only one direc I49. For slower de?ection rates, the inductive voltage tion in one branch circuit and only in the oppo site direction in the other. The de?ection coil di circuit has a high inductive reactance and low 75 La ‘ 2,412,291 has a lower value, .permittirrg’the use of a step down ratio and requiring thus a lower peak plate current from the power tube for a given de?ec tion. In this manner, the total voltage drop re flected‘into the plate circuit of the power tube can ‘be given the same value for different saw tooth slopes, with the power tube operating at maximum efficiency. Thus far the invention has been described only with reference to the use of modulated saw tooth de?ecting voltages. However, it is feasible to use modulated voltages of other shapes, for example, sinusoidal. The radial velocity of the ages and to add said unidirectional voltages to the respective distorted voltages from which they are derived. 2. A de?ection system for cathode ray tubes including a de?ection voltage generator and a plurality of variable'voltage dividers connected across the output circuit of said generator, a shaft connected to said voltage dividers, said voltage dividers being so constructed and ar ranged that the proportions of the output volt age appearing across the output terminals of said voltage dividers are uniquely related to the angular position of said shaft, means for com- - bining said voltages appearing at the output ter trace will vary with its radius, instead of being constant, as with a sawtooth signal.’ A circuit 15 minals of one ,pair of said voltage dividers to produce a voltage synchronous with and similar adapted for use with modulated sinusoidal deflec in wave shape to that produced by said de?ec tion signals is shown in Fig. 11. A source of sine tion voltage generator but having. an amplitude wave voltage, not shown, is connected across a proportional to the cosine of the angle of posi capacitive voltage divider like the voltage divider II in Fig. 3. The four output terminals are con 20 tion of said shaft, and means for combining the voltages appearing at the output terminals of a nected to the grids of ampli?er tubes I59, IGI, I63 and I65, respectively. The plate circuits of these tubes include the primaries of step-up transformers I61, I69, Ill and I13, which are tuned to resonate at the oscillator frequency. The transformer secondaries are connected to recti ?ers I15, I11, I19 and IBI which produce the mod- ' ulation envelope voltages on their respective loads, which are serially connected for each phase as shown to obtainthe complete summation waves 30 for rotation of the cathode ray beam. Radial modulation voltages are obtained directly from second pair of said voltage dividers to produce a second voltage synchronous with and similar in wave shape to that produced by said de?ection voltage generator but having an amplitude pro portional to the sine of the angle of position of said control shaft, means for amplifying said cosine proportional and sine proportional volt ages including networks which discriminate against the low frequency and direct current components of said voltages, means for compen sating said discrimination including switching the transformers, which are connected in pairs devices arranged to cause each cycle of said dis with primaries in opposite polarities and with proportionately ampli?ed voltages to form a pre secondaries in the same polarities and in series. 35 determined voltage level, and means for apply The radial de?ection voltages are coupled over ing said. voltages to respective rectangularly re capacitorsv I83 and I85 into the de?ection cir lated de?ection elements of a cathode ray tube. cuits'of the tube I81. Isolating impedances I89 3. A de?ection system for cathode ray tubes and I9I prevent these voltages from being short ’ including a de?ection voltage generator and a 40 circuited by the recti?er ?lter capacitors I93. plurality of voltage dividers connected across the Variation of the capacitors I83 and I 85. allows output circuit of said generator, each of said variation of the radial de?ection amplitude. voltage dividers comprising a variable capacitor Thus the invention has been described as a device for causing a radial de?ection of the beam of a cathode ray tube in a direction correspond ing to the angular position of a shaft, the direc tion of said de?ection being unique for each po sition of the shaft even at low or zero speeds of rotation. The required de?ecting voltages are derived by modulating the output of a. sawtooth * or a sine wave generator with a capacitive volt age divider-to produce component waves which are combined, ampli?ed, and applied to the de ?eeting circuits. Direct current components which are lost in the ampli?er and combining cir , connected in series with a fixed capacitor, a shaft ' connected to said variable capacitors, said var iable capacitors being so constructed and ar ranged that the proportions of the output volt age of said generator appearing across the out put terminals of said voltage dividers are uniquely related to the angular position of said shaft, means for amplifying said voltages in cluding coupling networks which discriminate against the low frequency and direct current components of said voltages, and means for com pensating said discrimination including recti ?ers arranged to derive unidirectional ‘voltages. proportional to the average components of said tion circuit. disproportionately ampli?ed voltages and to add I claim as my invention: said unidirectional voltages to the respective dis 1. A de?ection system for cathode ray tubes including a de?ection voltage generator and a 60 torted voltages from which they are derived. 4. A de?ection system for cathode ray tubes plurality of variable voltage dividers connected including‘ a de?ection voltage generator and a across the output circuit of said generator, a‘ plurality of voltage dividers-connected across the shaft for driving said voltage dividers, said volt output circuit of said generator, each of said age dividers being so constructed and arranged that the proportions of the output voltage of said 65 voltage dividers comprising a variable capacitor cuits are restored by a clamping or D.-C. inser generator appearing across the output terminals . connected in series with a ?xed capacitor, a shaft of said voltage dividers are uniquely related to the angular position of said shaft, means for am connected to said variable capacitors, said vari- ‘ able capacitors being so constructed and ar ranged that the proportions of the output voltage plifying said latter voltages including networks which discriminate against the low frequency 70 of said generator appearing across the output terminals of said‘ voltage dividers are uniquely and direct current components of said voltages, related to the angular position of said shaft, and means for compensating said discrimination ' means for amplifying said voltages including including recti?ers arranged to derive unidirec coupling networks which discriminate against tional voltages proportional to the average com ponents of said disproportionately ampli?ed volt 75 the low frequency and direct current components 9 2,412,291 10% of said voltages, means for compensating said ' frequency and direct current components of said _ discrimination including recti?ers arranged to voltages, means for compensating said discrim ination including recti?ers arranged to derive unidirectional voltages proportional to the aver age components of said disproportionately ampli ?ed voltages and to add said unidirectional volt~ ages to the respective distorted voltages from derive unidirectional voltages proportional to the average components of said disproportionately ampli?ed voltages and ‘to add said unidirectional voltages to the respective distorted voltages from which they are derived, and means for com pensating the losses in said rectifiers by pro viding corresponding attenuation of said dis torted voltages. 5.. The invention as set forth in claim 1 where in said last named means comprises diode rec ti?ers provided with low power factor load cir cuits. which they are derived, and means for combin ing said ampli?ed waves to produce voltage waves 10 synchronous with and similar in shape 'to that produced by said de?ection voltage generator - 6. A de?ection system for cathode ray tubes including a de?ection voltage generator and a plurality of variable voltage dividers connected but having amplitudes proportional respectively to the cosine and to the sine of the angle of posi tion of said control shaft, and means for apply ing said resultant voltages to corresponding de ?ection circuits of the rectangularly related de ?ection elements of a cathode ray tube. '7. The invention as set forth in claim 1 where shaft connected to said voltage dividers, said in said de?ection voltage generator produces an voltage dividers being so constructed and ar 20 amplitude of substantially sinusoidal wave form. ranged that the proportions of the output voltage 8. The invention as set forth in claim 1 Where of said generator appearing across the output in said ampli?er means includes resonant cir terminals of~said voltage dividers are uniquely cuits tuned to the repetition frequency of said related to the angular position of said shaft, de?ection voltage generator. across the output circuit of said generator, a means for amplifying said latter voltages includ 25 ing networks which discriminate against the low OTTO H. SCHADE.