DE847627C - Electronic phase shifter - Google Patents

Description

(WiGBl. P. 175)

ISSUED AUGUST 25, 1952

I he invention relates to a device for Departure of a precisely defined voltage pulse (chain of pulses) depending on the Appearance of a character pulse and in a predetermined and adjustable time or phase targeting to the character pulse. Such devices are for various control and .Xfeßzwecken and Rotation operations applicable. z. H. to determine the phase angle and the size of the Unbalance in rotors, for controlling welding devices, Visual regulation for printing presses, voltage regulators and for rotating current reversers purely directions, the light discharge vessels with (iitter or firing pin control and other applications that rely on periodically recurring Voltage pulses are based.

The subject of the invention is the creation of electronic phase squint of the type mentioned. which are able to produce a time-defined output pulse chain of 1> a certain waveform that has a much lower dependence on the presence of undisturbed input pulses, as is the case with the previously known devices is required. It is the aim of the invention that temporally defined output pulse practically independent of any irregularity in the Waveform of the input character and the delivery of an output pulse only through the Control occurrence of the forehead front of the sign.

According to the present invention there is provided an electronic amplifier for reception and amplification of the entrance sign with an electrical

electronically controlled pulse generator connected to a sharp pulse of defined amplitude and Width and a fixed phase relation to the front face of the sign. The impulse, des Generator is applied to an electronically controlled delay circuit, preferably of the type of the multivibrator (relaxation generator) and the time-determined output voltage is a second pulse generator supplied to a scha γιο fen output pulse of defined amplitude and Width to create ^ its phase relationship to the input character through the selected time setting of the delay circuit is determined.

Preferably the mentioned amplifier stage is provided with a phase selection and tube circuit combined, which allows the reversal or maintenance of the polarity of the characters, depending on whether the original sign has the required polarity.

It is also advantageous between the delay stage and the following pulse generation stage a differentiator to switch to the square waveform of the output voltage of the To convert the delay stage into positive and negative pulse peaks, which are responsible for triggering the Pulse generator are more suitable.

Several preferred embodiments of the invention are shown in the drawings.

Fig. 1 shows the circuit diagram of a pulse-shaping phase shifter according to the invention; in

Fig. 2 is a corresponding block diagram shown while

3 schematically shows an example of typical output voltages shows the corresponding stages of said device;

Figures 4, 5 and 6 show various changes of individual stages that are used instead of the corresponding stages shown in FIG can.

For the purpose of showing a complete and detailed example of an according to The device built according to the invention and operated with success are indicated in brackets below Notes on numerical resistance values and trade names of suitable electron tubes given. Of course, these reference values are only given by way of example the numerical values are primarily intended to serve as an indication of the order of magnitude. In general, a correct dimensioning of the impedance quantities, as usual, is required in order to achieve the best results zvi. The information in brackets is from a phase shift network, that for the regulation of the sine wave generator of an equipment for a balancing machine and it is obvious that other forms of application have parameter values, tubes or an amplifier stage number may require different from that of the examples given here.

In Fig. Ι are the entrance gills of the invention Device with 1 and 2 and the output terminals with 3 and 4. The device is fed by a constant voltage direct current source, shown schematically at 5. the positive voltage rail of this power source is denoted by 6. The negative rail 7 is grounded. A voltage source or a transmitter 10 is connected in parallel to the input terminals 1, 2, the supplies the pulse to be formed by the device. 7 "This source can consist of a vibration pickup, a photoelectric pulse generator, an alternating current generator with variable speed, or any other device capable of causing a voltage change depending on the effect to be considered.

The device according to the invention consists (see Fig. 2) of a phase selection stage 20, an amplifier and Sharpening stage 30, a differentiating stage 40, a pulse generator stage 50, a controllable time delay stage 60, a second differentiating stage 70 and a final pulse generation stage 80. A receiver is connected to the output terminals 3 and 4 90 connected, d. H. an a ^ orrichtuiig in which uses the shaped and properly timed output pulses from terminals 3 and 4 should be.

Typical examples of output waves for the aforementioned stages are at 11, 2 :, 31, 41, 51, 61, 71 and 81 (Fig. 3) shown schematically. To give an example of one of the various fields of application for which the inventive Apparatus suitable to mention it should be assumed that the primary source 10 of the input pulse an alternating current speed transmitter or photoelectric pulse generator is for use in a machine for dynamic balancing of rotating rotors to generate a reference voltage from an adjustable constant phase relationship to the number of revolutions of the rotor to be examined. To this end, the recipient can 90 consist of an electronic sine wave generator whose sinusoidal output voltage is fed to a wattmeter. Such a balancing device is as such known.

In detail, the input terminal 1 of the device according to FIG. 1 is connected via a capacitor 22 to the grid of a vacuum tube 23 (6SN7), the anode of which is connected to the positive rail 6 via a resistor 24, while the cathode is connected a resistor 25 is connected to the negative rail 7. The resistors 24 and 25 have approximately the same resistance values (47,000 ohms each). The anode and cathode of the tube 23 are connected to two contacts of a selector switch by the capacitors 26 (0.01 // F) and 2 ~ j (0.01 // F), respectively. The movable contact piece of the switch 28 is connected to the negative rail 7 via the resistors 32 and 32 '(ι megohms each) and is also connected to the control grid of a pentode 33 (6 S j 7) of the amplifier stage 30 via the resistor 32' . The switch 28 allows the output voltage (21 in Fig. 3) to be taken from the stage 20 either at the anode

resistor 24 or at the cathode resistor 25. The triode 2T ₁ does not act as an amplifier, but serves to ensure a desired polarity regardless of whether a negative or positive sign (11 in Fig. 3) is impressed on the grid of the tube. A positive output "is desired in the device shown. When a negative sign is pushed onto the (iitter, the sign appears reversed on the anode resistor 24 and this output is used. When a positive sign is fed to the (iitter, it appears positive on the cathode resistor 2 ^, and that exit is used.

The amplifier stage 30 has sufficient components or stages to provide a positive sign (31) of sufficient amplitude with a sharp wavefront. In the preferred embodiment, the booster stage consists of two tubes or tube sections. although multiple tubes can be used if necessary. The first amplifier tube 33, to whose control grid the switch 2S is connected. is a pentode. Its anode is connected to the rail 6 via a load resistor 34 (470000 ohms), while the cathode is connected to the rail 7 via the resistor 35 (1500 ohms). The bias voltage for the screen grid of the tube 33 is supplied via a resistor 3?) (2.2 megohms) connected to the positive rail 6. The screen grid is bridged to the earth rail 7 with a capacitor 37 (1 // F). The anode of the tube 33 is coupled via a capacitor 38 (0.01 // F) to the (iitter of a second amplifier tube 43 (6S 17), which receives a positive bias voltage from the rail 7 via the resistor 39 (i megohms) 33 acts as a normal amplifier with a high degree of amplification. Its output is fed to the tube 43, which sharpens the amplified symbol, ie gives it a very sharp wavefront. The anode of the R (its 43 is via a resistor 44 (470,000 () hm ) is connected to the positive rail 6. The cathode of the tube 43 is connected to the rail 7 via a resistor 45 (1500 Ohm) .

The tube 43 is normally conductive. The circuit components used in the example are has been chosen so that the tubes operate in the range of their normal current values. The potential of the The control grid is positive about "2 volts. The potential of the anode is about 15 volts. The screen grid has a positive potential of about 70 volts. In the operation, if a sign of sufficiently negative j tive value the control grid of the tube 43 is pressed the pipes are locked. At this moment the external voltage increases almost to j the value of the positive voltage on the rail 6.

As a result, the waveform (41 in Fig. 3) at the anode has a very steep vertical front. The consequence of this is that the tube 43, in conjunction with the amplifier tube τ, τ, transforms the wave image of the input character from a possibly very irregular waveform into an amplified wave of a sharply delimited wave front. The ('correspondence of the latter wave with the original wave of symbols is only available with regard to the temporal start of the symbol.

The output of the above-described amplification or sharpening stage 30 is the (jitter of a vacuum tube 53 (C) SX /) across from a capacitor 4S (IK) pF) and a resistor 54 (1 megohm) existing differentiating stage 40 supplied. This differentiating stage effects the shaping of the output voltage of the tube 43 into pulses of of the general type shown at 51 in Fig. 3 so that the jitter of tube 53 is positive (sharp short impulses), of which the first temporal with the steep wave front 41 coincides.

The tube 53 belongs to the pulse-shaping stage 50. I) This stage is essentially a single ended blocking generator. The tube 53 is negatively biased very much so that it is normally non-conductive until a positive mark on the grid renders it conductive. The Sperrspaimungspotcntial is the (iitter over the abutment edge 54 and a biasing resistor circuit. Consisting of the cathode resistors 55 (470000hm) and 56 (ioooOhm). Fed. The resistor 55 is in parallel connection with a capacitor ^^ '(0.1 // F) and in series with a resistor ~, γ (ο.22 megohms) between rails 6 and 7. The reverse voltage (20 to 50 volts) is large enough to cause tube 53 to respond only to positive input spikes or steep positive wave fronts, as they are supplied by the diflerential network 46, 54. A transformer 5S is connected to the anode circuit of the tube 53, the secondary winding of which is fed back to the (jitter of the tube 53 via a capacitor 5 <; (270 pF) a signal received at the (litter makes the tube S3 conductive, the resulting drop in the anode voltage acts on the (iitter via the transformer and controls the grid negatively, so that the R (" ll revert to hibernation. In this way, a single positive pulse 51 is triggered at the beginning of each positive grid symbol, whereupon the tube ^ $ becomes non-conductive again until the next positive symbol is received. The output voltage S1 is therefore a single sharp pulse of very short duration, for example on the order of a few milliseconds, the shape and size of the output pulse being independent of the shape of the symbol voltage 31 which triggers the pulse. The amplitude of the pulse can be changed by choosing the circular components, for example the cathode resistances of the tube 53. As for timing, the pulse 51 coincides with the steep front of the boosted character voltage 31.

The output pulses of the pulse generator stage 50 are fed to the delay stage 60. Hei the embodiment of Fig. Ι is the delay

grade a tilt circle of an ordinary cathode-coupled device Tilting vibration generator. The cathodes of the tubes 63 and 63 'are each shared by one Cathode resistor 62 coupled. The tubes can be converted into a single double triode (6 S N 7) can be combined. The anode circuit of the tube 63 closes one with a changeable one Resistor 65 (15,000 Ohm) series-connected rheostat 64 (20,000 Ohm) and an unto variable resistor 65 '(4700 ohms); the anode circuit of tube 63 'closes a resistor 66 (27,000 ohms) a. The grid of tube 63 'is given a positive grid bias a resistor 166 and is connected to the anode of tube 63 via the tap of the variable resistor 64, a selection switch 160 and a number of selection capacitors are coupled. Five such capacitors are labeled 171 to 175. These Capacitors have correspondingly graded capacitance values, between 0.05 / <F and 2360 pF. Therefore, the anode grid coupling within the relaxation oscillator can be set both at the resistance and by the choice of capacitance values. The grid of the tube 63 is about a Resistor 67 (0.1 megohm) with one of resistors 68 (39,000 ohms) and 68 '(0.24 megohms) t> existing voltage divider, which ensures a constant grid bias. Since the Tube 63 'is normally conductive due to its positive grid bias, the effect of the Cathode resistor 62, the load current flowing through the tube 63 'across the resistor 62 causes a voltage drop, sufficient to keep the tube 63 normally non-conductive.

The fed to the grid of the tube 63 from the oscillating tube 53 via a capacitor 69 (0.0 r kF) Output pulses 51 raise the grid voltage sufficiently to allow the anode current to flow to initiate, which causes a voltage drop ül> he the resistors 65 ', 65 and 64, so that the grid of the tube 63 'over the through the scarf! ter 160 selected coupling capacitor a different i reduced potential is supplied and the grid j of the tube 63 'immediately by a negative potential is blocked. At the moment when the; Current stops flowing through tube 63 ', falls! the voltage drops the cathode resistor 62. This makes the tube 63 fully conductive while the tube 63 'remains non-conductive. The coupling capacitor then gradually charges up, see above that the grid voltage of the tube 63 'again in agreement with the exponential increase the voltage of the coupling capacitor increases. Therefore, the tube 63 'becomes conductive again and controls the grid of tube 63 by increasing the voltage drop across cathode resistor 62 back into the negative, so that the original state is restored.

From the described mode of operation of the tilt generator circuit it follows that the switching or the tilting process between the tubes 63 and 63 'occurs at a point in time which lags behind that of the trigger signal by a period which is determined by the parameters of the capacitive anode grid coupling circuit. As a result, the time lag of the switching point in time is determined by the value of the selected capacitance and by the setting of the variable resistor 64 and by the values or resistance values of the other resistors in the capacitive discharge circuit. The Ausgangsspannuug the \ ^T erzögerungsstufe between the anode of the tube 63 and the common negative rail 7 has shown a rectangular waveform such as at 61 in FIG. 3. The point in time of the appearance of the steep front α of the square wave 61 is determined by the individual symbol pulses 51 from the previous pulse-forming stage. Therefore, if the pulse 51 occurs at a constant frequency, the respective fronts α and h maintain a constant time interval l> ei. However, the timing or phase position of the intermediate front c with respect to the front α is determined by the switchability in the time delay stage l> and can therefore be shifted in any direction with respect to the wave period depending on the selected setting of the delay stage, as mentioned above will.

The anode of the tube 63 is coupled to the grid of the tube 83 (6 SX 7) of the final pulse generation stage go through a capacitor 76. This capacitive coupling represents the above-mentioned differentiating stage 70. Its effect is to convert the output voltage of the delay stage e into pulses of the type shown at 71 in FIG. 3, so that negative and positive spikes are impressed on the grid of the tube 83. The negative spikes a ' and b' coincide with the front α and b of the square wave 61 and iha.beη therefore have a fixed time relationship to the pulses 51 or the fronts of the character voltage 1 r. The positive peak c of the pulse 71 coincides with the edge c of the square wave 61 and therefore has an adjustable phase with respect to the positive peak α 'or //.

The final pulse generation stage 70 consists of a single ended blocking generator and is similar to the pulse generator stage 50. The reverse voltage for the tube 83 is provided by a grid resistor 84 (0.1 megohm) and two cathode resistors 85 (13,000 ohms) and 86 (1,100 ohms), the resistor 85 in parallel with a capacitor 85 '(0, 1 / (F) and is connected in series with a resistor ^ y (0.22 megohms) between rails 6 and 7. The anode circuit of tube 83 includes a transformer 88, the secondary winding of which is connected to a capacitor 89 (2000 pF) The effect of this blocking generator is similar to that of the pulse generator stage 50. As a result, the spikes α 'and b' of the pulse 71 pressed on the grid of the tube are ineffective, so that only the positive spike c ' triggers the oscillator and therefore causes the transmission of a single pulse of a certain amplitude and width, as shown for example at 81 in Fig. 31. This pulse is transmitted to the receiving device 90 via the output terminals 3, 4

any suitable coupling device such as coupling capacitor 92 (0.01 // F) pressed on.

From the above it follows that the single-ended output pulse 81 of the derate through the front of input character 1 1 is triggered, but from some irregularity in the waveform of the input character is not affected and that the output pulse has any desired delay given immediately on the front of the entrance sign can be achieved by setting the device's delay level accordingly. The device works so as a precise phase shifter. If z. B. the receiver QO is a sine wave generator and the Transmitter a photoelectric gel that is part of the rotor balancing equipment, then the sine wave generated under the control by the output pulse 81 has an accurate one The relationship between the rabbits and those recurring from the gel Character pulses and this phase relationship can be selected by setting the delay stage and be moved.

The advantages of the phase squint according to the invention emerge from a brief comparison with comparable known devices. In the case of the known electronic phase shifters, the input character first reinforced to get a sufficiently high and steep front and that reinforced Character is then sent through a limiter circuit, so that a kind of square wave form 111 results. This ax signal is then subjected to a phase shift and, if necessary, to Control or triggering of the receiving device used. Such a phase squint> it requires one relatively low input pulse to ensure reliable and accurate operation, because deep indentations appearing in the input shaft after its initial front act like an n-new symbol and can therefore disrupt operation.

In addition, the type of phase shift is of limited accuracy and limits the range when the input character has a greatly varying amplitude. This is due to the fact. that, while the delimiter circuit can ensure a constant amplitude of the modified, that is, truncated character, the steepness and width of the truncated character changes with the changing amplitudes of the input character and the width of the truncated character changes over a substantial amount of degrees compared to the total - Roughly (360 °) a working period extends. The variable width of the truncated character Ije affects the accuracy of the phase setting ^!

ment, and the relatively large width of the older rectangle of the truncated character delimits the extent of the achievable phase shift, so that displacements of more than i8o ° and up to 360 are close to ⁰ difficult or not practical adjustable. In contrast to this and as mentioned above, those of the delay stage and those of the output circuit of the invention are used The pulses supplied to the device are generated by separate ■ pulse generators regardless of the waveform of the input character and always have a precisely defined and precisely adjustable pulse shape of very small width. As a result, the inaccuracies and limitations of the phase shift caused by the cut square waves are avoided and a very stable delay is ensured. Insljesondere the extraordinary sharpness allows the light emitted from the pulse-forming stage pulses without difficulty an accurate phase shift of more than 180 "to near 360 ⁰ and are therefore far superior in this respect to known devices.

The above-mentioned embodiment of the invention represents a preferred arrangement in which the individual stages of the device can be modified and replaced by other suitable circular elements. For example, one or the two pulse generator stages 50, 80 can hold a preloaded gastriode in which a capacitor is connected between anode and cathode. An example of such a modified generator stage is shown in FIG. A gastriode 103 is connected with its anode via a resistor 104 to the positive rail 6. The cathode is connected to the negative rail 7 via a resistor 105. A grid resistor is denoted by 106. A capacitor 107 is connected in the anode circuit. The capacitor 107 is originally charged to a high value by the supply voltage from the rails 6 and 7. When a positive sign (31 or c in 71 in Fig. 3) is applied to the grid, the tube becomes conductive, the capacitor 107 discharges, and the voltage at the anode becomes such that the tube does not allow ionization. The tube is then switched off until the charging time components of the capacitor have become sufficiently effective. The output voltage of this circuit is a short pulse similar to pulse 51 or 81 in FIG. 3.

The delay stage 60 can be implemented as a ripple generator, as shown, for example, in FIG. 5. The resonant circuit is equipped with a five-grid tube 113 (6 SA 7), the grid of which is denoted by the reference numerals 114 to 118. The control grid 116 is overall to the preceding pulse forming stage via a capacitor 119 coupled n is _0, which in terms of its terminal, corresponding to in FIG. 1, the capacitor 69th A constant grid bias is applied to grid 116 from a voltage divider made up of resistors 120 and 121. The grid circuit for the n ₅ control grid 116 also includes a cathode resistor 122, so that the resulting grid voltage also depends on the voltage drop caused by the current flow in the load circuit across the cathode resistor, the aforementioned load circuit also including an anode resistor 123. The control grid 114 receives a positive bias through a resistor 124 and is coupled to the anode through a capacitor 125. The screen grids 115 and 117 are made up of the resistors 126 and 127 by a tension

voltage divider biased, the braking grid 118 is connected to the cathode.

The grid 114 normally allows electrons to flow from due to its positive bias the cathode, while the grid 116, which is normally negatively biased, prevents the flow from to reach the anode so that the electrons are collected by grids 114 and 115 and the current in the anode resistor 123 is normally ο. Hence one can look at the anode part of the tube circle as a normally off tube and the cathode part as one normally Imagine switched-on tubes which are comparable to tubes 63 or 63 'of the relaxation generator shown in FIG is.

When a positive pulse arrives at the control grid 116, which controls this grid to be switched on, part of the electron flow from the cathode receives access to the anode. This causes over that Anode resistor 123 has a voltage drop that charges the coupling capacitor 125 and therefore the voltage at the control grid 114 is in agreement decreased with the time characteristic of the capacitive coupling circuit.

As a result, the voltage of the grid 114 drops below the pickup point, so that the entire Discharge path becomes non-conductive until the subsequent discharge of the capacitor 125 the grid 114 again rises above the response point. This is the original condition of the tubes up to The arrival of a further positive sign at the grid 116 is restored. The amount of delay with regard to the time of arrival of the character pulse depends on the time constants of the Tube circles, especially those of the capacitive coupling circuit, and can through Change in the bias voltage on the grid 116 can be adjusted by means of a variable resistor 121. The change in timing or phase shift so achievable is essentially one linear function of the adjustable grid bias for character pulses with. constant amplitude, Another embodiment of the delay stage 60, which instead of the arrangement shown in FIG is applicable, is shown in Fig. 6 in connection with elements of the subsequent differentiating and pulse generator stage shown. The delay stage according to FIG. 6 is essentially a ripple generator of the same type as that shown in FIG. Therefore, the tubes 163 and 163 'correspond to the tubes 63 and 63 'of FIG. 1 and the circular elements marked with the same reference numerals in FIGS. 1 and 6 are equal to each other and connected to each other in a corresponding manner. The difference However, a single capacitor 167 of FIG in the embodiment of Fig. 6 for coupling the grid of tube 163 to the anode of the tube 163 'used. The anode resistance 169 of the tube 163 in Fig. 6 has a fixed value and that The grid of tube 163 in Fig. 6 receives an adjustable rather than a constant bias from the potentiometer 168, which takes the place of resistors 68 and 68 'of FIG.

What now with respect to time delay and phase shift of the arrangement shown in Fig. 6 relates to the effect, this is similar to Figure ι. V shown ^he deceleration stage with the exception that the delay is not due to a change in the anode grating coupling between the tubes 163 and 163 ', but by setting the constant grid bias on tube 163 at variable resistor 168. When the bias voltage at variable resistor 168 is decreased, the current in tube 163 is decreased during the relaxation generator pulse. The consequence of this is that the anode voltage of the tube 163 becomes higher and the cathode voltage becomes lower during the pulse. The exponential increase in the grid voltage of the tube 163 therefore begins at a higher voltage and ends at a lower voltage, and the turn-off time of the tube 163 'is reduced. The Kippgeneratorimpuls is therefore shorter due to the decreasing voltage at the grid of the tube 163 and longer due to the increase in this voltage.

Since the devices according to the invention, as mentioned, are suitable, a precisely determined and optionally timed output pulse depending on input pulses from any SeIl) St to deliver strongly irregular incoming impulses can such a device with different Types of pulse generators or generators regardless of the particular voltage-time characteristic of the supplied pulse can be driven. S such devices are for the study of any stage j an oscillation or periodic phenomenon j suitable. Furthermore, in many forms of application, a close examination of each phase can be carried out circumferential movement take place, even if initiated by a simple vibration transmitter will.

The device can be easily used as a precision timing device by comparing the time of occurrence of the output pulses (51 and 81) from the first and last impulse-generating stage. This type of precision control allows one to be down to microseconds precise timing over a wide frequency range including the 60 period or other network frequencies. The device can, for example, apply to all devices that require a quickly recurring time control or cycle period, such as. B. the controller of gastriodes or ignition pin vessels in welding machines with special rectifiers. To the temporal The first pulse generator stage 50 is preferably provided to facilitate control processes of this type equipped with an externally accessible output terminal. In the embodiment of FIG such a terminal marked with 8 Ix with the cathode the tube 53 connected. It is then possible to use the output pulse via terminals 3 and 4 the output pulse via terminals 8 and 4, for example by means of a comparator or Mixed network, as is customary for such purposes, to be compared.

From ck'i "dal.S foregoing description is ersicht-1 icli. Ertindur.g which represents an electronic phase shifter for recurrent pulses (kr an accurate shift of the output pulse with respect to the time of arrival of Eingangszeie'heiis by an amount to via iSo and vi-cl closer to a full periodiVerschielmng, (1st left at 3C) O than was possible with the known devices of this type

ίο is suitable for the timing of rapidly recurring phenomena, / .. 15. of a frequency of 20 periods per second and noo periods per second and more and can send out two predetermined and precisely defined timing impulses depending on an eventual signal, with one impulse has a fixed 1 mias ratio for the sign and the other is precisely phase adjustable over a wide range of the working period.
The device can be used as an electronic phase shifter for rotor balancing devices to ensure a precisely adjustable phase relationship between a sine wave generator and another periodically operating component of the execution and an input signal controlled by the rotation or oscillation of the rotor to be balanced. It represents a phase shifter which works reliably at high rotor speeds of up to 30,000 L / min or 36,000 LYmiu (600 l '/ sec) or higher, even if the input from a photocell or a vibrator with a highly irregular output characteristic is delivered.

Claims (7)

PATENT CLAIMS: i. Electronic phase shifter for measuring and control devices with periodically recurring voltage pulses using an amplifier equipped with input terminals to accept a symbol (30) and an output circuit for supplying an increased signal voltage by a pulse generator (5 «), which with this Output circuit for tripping by the aforementioned boosted voltage is connected to a to deliver a first pulse of a given phase position with respect to the character, an adjustable one Time delay stage (60) connected to the first-mentioned pulse generator, and a second pulse generator (So) connected to the delay stage and to output terminals is equipped to deliver a further pulse at these output terminals, the phase ratio of which to the first pulse depends on the setting of the delay level. 2. Apparatus according to claim 1, characterized in that the time delay stage (60) Tube circles (03, 63 ') includes in order to depend from the first pulse to deliver a voltage wave, these circles being adjustable elements (160, 64) have to cross the zero crossing of this voltage wave with respect to the mentioned To delay phase position adjustable, and that a Differentiereinriehtung (70) with the mentioned Time delay stage is connected to tile wave (61) in a Spamiungsspitze (71) to transform the second mentioned Pulse generator (80) is supplied. 3. Apparatus according to claim 1 or 2, characterized in that the input circuit of the amplifier (30) is connected to an electrical phase selection stage (20) which has an input circuit (1, 2) for recording a character and an output circuit with a selector switch ( 2S) in order to transfer the character in a certain polarity to the \ ^{T more} powerfully. 4. Apparatus according to claim 2, characterized in that the time delay stage (60) includes a square wave generator (63, 63 ') whose output shaft (61) passes through an I) zodiac (70) is converted into positive and negative peaks, and the second pulse generator (So) is designed so that it through points (c "') d-er one, with the XV.ll passages ii (r) of the stress wave (61) coinciding polarity is triggered and another one with these Xulldurehgang (c) provides coincident momentum (Si). 5. Apparatus according to claim 4, characterized in that the square wave generator (^ 3 * ^ 3 ') ordered ^from a cathode-coupled wave generator which has an input grid circuit (68, 69) connected to the first pulse generator (50) and means (64, 171 ) for setting the grid bias in order to adjustably delay the passage of zero of the square wave (61). 6. Apparatus according to claim 5, characterized in that the tilt generator comprises a normally switched off tube (63) and a normally switched on tube (63 ') each provided with a cathode, an anode and a grid, the cathodes having a common one Have cathode resistance (62) and the (litter of the normally switched-off tube is connected to the first pulse generator (50) so that it is triggered in response to a pulse (51) supplied by this generator (50), while a variable capacitance (171 ) the anode of the normally switched off tube (63) couples with the (jitter of the normally switched on tubes (63 '), whereby the tilt generator generates a square wave (61), the mean X ^T ull passage with respect to this pulse by an amount is delayed, which depends on the setting of the coupling circuit (64, 171). 7. Apparatus according to claims r to 6, characterized in that the pulse generators (50, So) are blocking oscillators. 1 sheet of drawings 5308 8.52