US2680830A - Series-resonant high-voltage supply - Google Patents

Description

June 8, 1954 P. G. SULZER 2,680,830

SERIES-RESONANT HIGH-VOLTAGE SUPPLY Filed April 28, 1953 2 Sheets-Sheet l INVENTOR Pezer G. julzer' BY WZM 'AGENT June 8, 1954 P. c. SULZER 2,680,830

SERIES-RESONANT HIGH-VOLTAGE SUPPLY Filed April 28, 1953 I 2 Sheets-Sheet 2 W 8 INVENTOR Pezer 6. Suizer BY W75 Patented June 8, 1954 SERIES-RESON ANT HIGH-VOLTAGE SUPPLY Peter G. Sulzer, Kensin United States of Am the Secretary of Com gton, Md., assignor to erica as represented by merce Application April 28, 1953, Serial No. 351,765 11 Claims. (01. 321-2) (Granted under Title 35, U. S. Code (1952),

sec. '266) The invention described herein may be manufactured and used by or for the Government of the United States for governmental purposes without the payment to me of any royalty thereon in accordance with the provisions of 35 U. S. Code (1952), section 266.

The present invention relates to a high-voltage supply and in particular to an oscillator type direct cur'rent high-voltage supply which can be built with readily available components. The oscillator-type direct-current supply has been employed in Oscilloscopes and television receivers in order to eliminate the heavy and bulky components required to produce rectified and filtered high voltages directly from the power frequency. The previous oscillator-type direct-current supply consisted of an oscillator tube, a transformer, and a rectifier and filter. The transformers used in such a supply were specially designed for specific purposes and are not readily available in sizes other than those used in oscilloscopes and television receivers. The design of'such transformers for special purposes is often tedious and time-consuming and imposes a serious limitation upon the design ofspecial supplies of this type.

It is therefore the primary object of the present invention to provide oscillator-type directcurrent supplies which do not require the use of high-frequency transformers.

Another object of the present invention is to provide oscillator-type direct-current supplies which may be constructed from readily available electrical components.

Another object of the present invention is to provide oscillator-type direct-current supplies which may be designed to cover widely varying voltage and power requirements.

Another object of the present invention is to provide an oscillator-type D.-C. supply in which the filament of the rectifier tube is heated by the oscillatory voltage in the oscillator circuit.

Another object of the present invention is to provide an oscillator-type D.-C. supply in which a modified Colpitts-type oscillator may be used as the source of oscillatory voltage, the modification of the oscillator allowing higher voltages to be obtained than are normally available from this type of oscillator.

In accordance with the present invention there is provided a modified Colpitts-type oscillator in 7 which there is a series-resonant circuit consisting of an R.-F. choke and several series capacitors. The voltage is rectified by a diode which has its filament connected in series with the resonant circuit. By various modifications of this circuit, negative or positive direct-current voltages may be obtained, or both positive and negative voltages may be obtained from the same unit.

Other uses and advantages of the invention will become apparent upon reference to the specification and drawings.

Figure 1 is a circuit diagram of a modified Colpitts-type oscillator which may be used with the present invention.

Figure 2 is a circuit diagram showing a negative high-voltage supply.

Figure 3 is a circuit diagram showing another embodiment of the invention showing a positive high-voltage supply.

Figure l is a circuit diagram of another embodiment of the invention in which both negative and positive high voltages are obtained using a single rectifier.

Figure 5 is a circuit diagram of another embodiment of the invention in which both negative and positive high voltages are obtained, in which two rectifier tubes are employed.

Figure 6 is a circuit diagram of another embodiment of the present invention in which two rectifiers are used to obtain a positive voltage which is equal to twice the voltage obtained in the circuit of Figure 3.

Figure 7 is a circuit diagram of another embodiment of the present invention showing the use of a tetrode as the oscillator tube in the negative high-voltage supply.

Figure 8 is a circuit diagram of another embodiment of the invention in which a grounded cathode oscillator is used.

Referring to Figure 1, there is shown a modified grounded cathode Colpitts oscillator. The oscillator comprises a triode I I having a grounded cathode I2 and a plate l3 connected through an R.-F. inductor It to the B+ supply. The grid i5 is grounded through capacitor l9 and gridleak resistor 15. In this circuit feedback between the plate !3 and grid It is accomplished through the inductor I l and capacitor it. In the standard Colpitts oscillator the capacitor it has a very low reactance and is inserted for the purpose of direct-current blocking. In the circuit as modified for the purpose of the present invention the reactance of the capacitor I3 is comparable to the reactance of the inductor ll. The capacitive reactance of the capacitors !8, IS, and 21 in series, is equal to the inductive reactance of inductor II; that is, in order that this circuit may oscillate, the capacitive reactv ance of capacitors l9 and 2| in series must equal the inductive reactance of the series circuit of capacitor l8 and inductor ll. By this procedure the voltage in the series-resonant circuit is increased over that normally obtained at this point in the standard Colpitts oscillator by a factor equal to the Q or the inductor ll. Therefore by varying the Q of the inductor II, it is possible to vary the direct-current output voltage.

Figure 2 is one embodiment of the present in vention using the (Jolpitts oscillator modified as indicated above. In this figure a grounded-plate oscillator is used instead of the grounded-cathode oscillator of Figure 1. Elements corresponding to those of Figure 1 carry the same reference numerals. In this circuit the filament 22 of the diode 23 is connected in series with the seriesresonant circuit between the capacitor l8 and inductor [1. The plate M of thediode'is' grounded through capacitor 26. The negative high voltage Hv is taken off between the plate and the capacitor 28. The oscillatory voltage in the series-resonant circuit provides the heater current for the filament 2. Upon a negative swing of the voltage in the series-resonant circuit the filamentary cathode 22 becomes negative with respect to the plate the electrons fiow through the inductor H, filament 22, plate it, and capacitor 26. This charges the capacitor so that the upper plate is negative with respect to the lower plate. Since the lower plate is grounded, the voltage on the upper plate is negative with respect to ground. During a positive swing oi the voltage in the resonant circuit, the tube is biased oii and capacitor 25 then provides the negative voltage. This capacitor is recharged during each negative swingof the oscillatory voltage to the extent that it is discharged while the tube 23 is nonconducting; that is, capacitor 23 also acts as a filter. The capacitor 26' is charged to a value approximately equal to the amplitude of the negative voltage peaks.

Figure 3 is another embodiment of the invention showing a positive high-voltage supply. In this figure the plate 2 of the diode 2-3 is grounded, and the capacitor 26 is connected between the inductor ii and ground. The. operation of this circuit is the same as in Figure 2 except that what was the upper plate in Figure 2 is now grounded and therefore the capacitor now has a positive voltage across it with respect to ground.

Referring to Figure 4, the plate 2 of the diode 23 is connected to ground through the. capacitor 25 and the inductor ii is connected to ground through the capacitor 22a. If the capacitors 263 and 26a are of equal value, the voltage will divide equally across these capacitors and the value of the output voltage at each point is equal to onehalf the voltage obtained in Figures 2 and 3.

In Figure 5, two diode rectifiers are used to obtain both positive and negative voltage outputs, the amplitude of each of the output voltages being equal to the amplitude of the voltage obtained in Figures 2 and 3. In this figure the first diode 23 has its filament 22 connected in series with the capacitor 58 and inductor ll, and inductor 5? is grounded through the resistor 2?. The second diode 23a has its filament 22c connected in series with the capacitors 2S and 29. The series circuit, comprising capacitor 23, filament 22a, and capacitor is connected in parallel with the resistor 2?. The plate Etta of the diode 23a is connected between the filament 22 and inductor ll. During a negative swing of the voltage in the resonant circuit, the filament *2 of the diode 23 becomes negative with respect to the plate and the diode conducts, charging capacitor 26 through the circuit consisting of resistor 27, inductor l1, diode 23, and capacitor 26. The nega tive high voltageis taken across capacitor 26.

During a positive swing of the oscillatory voltage in the series-resonant circuit, the filament 22a of diode 23a becomes negative with respect to the plate 24a as the result of the drop across inductor H. The diode 2 5 conducts and the capacitor 29 is charged through the series circuit consisting of capacitor 29, tube 230., filament 22, capacitor l8, gridleak resistor 15, and the R.-F. choke hi. Both of the latter elements offer low impedance paths to direct current. Since the left-hand" plate of the capacitor is grounded, the right-hand plate is positive with respect to ground. In this circuit the resistor 21 provides a ground return for the D.-C. voltage through the diode 23, and the capacitor 28 isolates the filament 22a from ground.

Figure 6 is another embodiment of the invention in which a positive output voltage equal to twice the voltage obtained in the circuit of Figure 3 is produced. In this embodiment the-plate 24 of the diode Z3 is connected between the filament 22 and the inductor ll. In this modification the diode 23 operates as a clamp which causes the negative peaks of the oscillatory voltage in the resonant circuit to be at ground potential. This is accomplished in the following manner: Initially, upon a negative swing of the voltage in the resonant circuit, the tube 23 conducts and charges the capacitor law a value equal to the value of the negative peak with respect to the center line of the oscillating voltage. Therefore, the charge developed across the capacitor prevents the filament 22 from going below ground potential during the negative swing or" the voltage. During a positive excursion of the voltage, the diode 23 is nonconducting. As a result'the voltage in the oscillatory circuit must vary above ground potential, and the voltage in this circuit rises to a value above ground equal to the voltage between the negative and positive peaks. During the rise of the voltage above ground the voltage drop across the inductor il causes the filament Hoof the diode 23a to'be negative with respect to the plate 26a and the tube conducts, thereby chargingthe capacitor 29 to a value equal to the difference between positive and negative peaks of the oscillatory voltage of the resonant circuit. The capacitor 29 is charged through diode 23a, filament 22, capacitor l3, resistor l5, and inductor M. This, of course, discharges capacitor IE to the same extent that capacitor 29 is discharged when the tube 23a is not conducting. Therefore, the average voltage across capacitor I8 is slightly less than the negative peaks of the oscillatory voltage. As result the output from capacitor 29 is not truly twice'the voltage developed in Figure 3 but is slightly less, depending upon the amount the capacitor-2E2 is discharged when the tube 23a is nonconducting.

In Figure 7 there is shown an embodiment of the invention which is similar to that shown in Figure 2. In this case a tetrode is used as an oscillator tube. The inductor 3E operates to iso-- late the screen from ground for R.-F. voltage and the capacitor 22 operates as a screen or-pass to hold the screen at cathode potential. Other than this the operation of the circuit is the same as that of Figure 2.

Figure 8 shows an embodiment of the invention in which a grounded cathode oscillator is used. The oscillatory circuit consists of capacitors i8 and I9, inductor i1, and capacitor 2i. tifying action of the tubes 23 and 23a is as described in Figure 5. Resistor the same function with regard to R..-F. blocking as the inductor 3! in Figure 7. rhe resistor 33 operates as an R.-F. block while passing direct current. The voltage output is taken across the capacitor 29, the same as in Figure t.

From the above, it should be apparent that the present invention may be used with a triode or tetrode oscillator tube and with a grounded plate, grounded cathode, or grounded grid oscillator. The values of capacitors i8, i9, 2 l, and inductor ll will depend upon the magnitude of the voltage output. The current-carrying capacity of these elements will naturally depend upon the power consumed by the output load. Similarly, the types of diodes used will depend upon the voltage and power requirements of the system, but in general the tube type 1133 Also a heated-cath0de type diode may be used. In such a case the filament will be connected as shown, and the cathode will be connected to one side of the filament.

It will be apparent that the embodiments shown are only exemplary, and that various modifications can be made in construction and arrangement with the scope of my invention as defined in the appended claims.

I claim:

1. A high-voltage, direct-current supply, comprising an electron tube oscillator, said oscillator having a series-resonant circuit, at least one electron tube rectifier, said rectifier having at least a filament, said filament connected in series with said series-resonant circuit.

2. A high-voltage, direct-current supply, com prising an electron tube oscillator, said oscillator having a series-resonant circuit, at least one electron tube rectifier, said rectifier having at least a filament and a plate, said filament connected in series with said series-resonant circuit, and means for connecting said plate so as to maintain said plate positive with respect to said filament during a portion of the negative swing of voltage in said series-resonant circuit.

3. A high-voltage, direct-current supply, comprising an electron tube oscillator, said oscillator having a series-resonant circuit, at least one electron tube rectifier, said rectifier having at least a filament and a plate, said filament connected in series with said series-resonant circuit, and means for maintaining said plate positive with respect to said filament during a portion of the negative swing of voltage in said series-resonant circuit.

4. A direct-current voltage supply, comprising means for producing an oscillating voltage, said means including a series-resonant circuit, second means for rectifying said oscillating voltage, said second means including at least one electron tube filament connected in series with said seriesresonant circuit.

5. A high-voltage, direct-current supply, com- The recthe same 3m performs prising an electron tube oscillator, said oscillator having a series-resonant circuit, a rectifier having a positive and a negative terminal, said negative terminal connected in said seriesis satisfactory.

d resonant circuit, and means for connecting said positive terminal so as to maintain said positive terminal positive with respect to said negative terminal during a portion of the negative swing of the voltage in said series-resonant circuit.

6. A highvoltage, direct-current supply, com prising an electron tube oscillator, said oscillator having a series-resonant circuit comprising an inductor and at least one capacitor, a rectifier having a positive and a negative terminal, said negative terminal connected to said seriesresonant circuit between said inductor and said capacitor, and means for connecting said positive terminal so as to maintain said positive terminal positive with respect to said negative terminal during a portion of the negative swing of the voltage in said series-resonant circuit.

7. A high-voltage direct-current supply, comprising an electron tube oscillator, said oscillator having a series-resonant circuit, at least one rectifier, said rectifier having at least a filament and a plate, said filament connected in series with said series-resonant circuit, a capacitor, said plate connected to ground through said capacitor.

3. The invention according to claim 7 in which said series-resonant circuit is grounded through a resistor, a second rectifier having at least a filament and a plate, a second capacitor, and a third capacitor, said second capacitor, said filament, and said third capacitor being connected in series with each other and in parallel with said resistor, the plate of said second rectifier being connected to the filament of said firstmentioned rectifier.

9. A high-voltage, direct-current supply, comprising an electron tube oscillator, said oscillator having a series-resonant circuit, a capacitor, one terminal of said series-resonant circuit connected to ground through said capacitor, at least one rectifier, said rectifier having at least a filament and a plate, said filament connected in series with said series-resonant circuit, and said plate connected to ground.

10. The invention according to claim 9, comprising in addition a second rectifier having at least a filament and a plate, said filament connected between said capacitor and said seriesresonant circuit, and said plate connected to the filament of said first-mentioned rectifier.

11. A high-voltage, direct-current supply, comprising an electron tube oscillator, said oscillator having a series-resonant circuit, a capacitor, one terminal of said series-resonant circuit connected to ground through said capacitor, at least one rectifier, said rectifier having at least a filament and a plate, said filament connected in series with said series resonant circuit, a second capacitor, said plate connected to ground through said second capacitor.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 2,373,165 Camein Apr. 10, 1945 2,443,619 Hopper June 22, 1948 2,543,632 Hudson Feb. 2'7, 1951 2,644,917 Smith July 7, 1953

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