USRE21749E - Regulating device - Google Patents

Description

-MflrCh 11, 1941. w VANCE REGULATING DEVICE 2 Sheets-Sheet 1 Original Filed Oct. 51, 1955 HIS HTTOFINE Y INVENTOR ArthurWVance -March1l,1941. NC Re. 21,749

REGULATING- DEVICE I Original Filed Oct. 31, 1933 2- Sheets-Sheet 2 -=I.I I I I I I I I*- INVENTOR I ArthdrWT/lpnce Mm BY 33 HIS HTTOHNE Y ReiuuedMarrll, 1941 UNITED STATES momma nnvron Arthur w. Vance, Haddonfleld, N. 1., alaignor to Radio Corporation of America, a corporation of Delaware Original No. 2,075,966, dated April 6, 1037, Serial No. 696,001, October 31,1933. Application for reissue December 22, 1938, Serial No. 247,305

24 Claims.

My invention relates to regulating devices and particularly to low impedance voltage regulating and current regulating circuits which utilize electric discharge tubes for maintaining either a constant voltage or a constant current output.

There are many applications for a high voltage source which has a low impedance and a more constant voltage output than can be obtained from a rectifier and filter system. As an example,

television amplifiers cannot be supplied with volt age from a filter system with satisfactory results,

Previously, in cases where the voltage requirements have been so strict, it has been necessary to employ batteries made up of a large number 16 of cells. Such batteries are expensive and must be replaced periodically.

There are also many applications for a low impedance source which supplies a constant current regardless of adverse conditions such as g9 varying load impedance or varying line voltage.

It is, accordingly, an object of my invention to provide a regulating circuit which will hold the voltage across a load constant when the voltage is supplied from a source of varying voltage such 25 as a source of rectified current.

A further object of my invention is to provide an improved current regulating circuit which will supply a constant current to a load.

A still further object of my invention is to 30 provide voltage and current regulating circuits of the above-mentioned types which do not have any batteries therein.

In practicing certain embodiments of my in vention, I connect a power tube in series with u the load, and vary the impedance ofthe power tube in accordance with voltage'changes by connecting the control grid of the power tube to the output circuit of a direct current amplifier, the input circuit of the direct current amplifier being 40 connected to a resistor shunted across the load. In certain specific embodiments, all batteries,

such as grid biasing batteries, are eliminated by utilizing a glow tube in one of two voltage-opposing circuits.

45 In practicing other embodiments of my invention, a power tube is connected in shunt to the load instead of in series therewithj Also, in certain embodiments, a resistor is connected in series with the load, instead of in shunt to it,

so for applying a regulating voltage to the grid of the power tube.

Other features and advantages of my invention will appear from the following description taken. in connection with the accompanying a drawings, in which Figure 1 is a. circuit diagram of a voltage regulating system constructed in accordance with one embodiment of my invention; v

Fig. 2 is a circuit diagram of the voltage regulator which, in accordance with my invention, 5 does not require the use of batteries;

Fig. 3 is a circuit diagram of a voltage regulator constructed in accordance with another embodiment of my invention; and

Fig. 4 is a circuit diagram of a current regulal0 tor constructed in accordance with one embodiment of m invention.

Referring to Fig. 1, a load is supplied with direct current from a full wave rectifier 01' conventional design. The rectifier i comprises recl5 tifier tubes 3 and 5 having hot cathodes l and 3, respectively, which are supplied with current from the filament secondary winding l i of a supply transformer iii. The anodes l5 and ll of the rectifier tubes 3 and. 5, respectively, are connected to the ends of the high potential winding 13 .of the transformer i3.

' A conductor 2| leading from the mid-point of the secondary winding I9, which forms one output lead or terminal of the rectifier I, is grounded and connected to the bottom terminal of the load 23.

The other output lead or terminal 25 of the rectifier i is connected to the upper terminal of the load 23 through a filter choke 21 and a power tube 29. This connection may be traced from the rectifier i through the choke coil 2'! to the plate 3| of the power tube 29, through the spacecurrent path in the tube to the filament 33 and through the filament shunting resistor 35 and 35 the conductor 31 to the upper terminal of the load 23.

The usual filter condenser 39 is connected be-. tween the load end of the choke coil 21 and ground. It will be apparent that the voltage supplied to the load 23 would have a fairly large hum component it only the choke coil 2'! and condenser 39 were relied on to filter the rectifier output. Therefore, in accordance with my invention, I provide a direct current amplifier I so connected in the circuit that the plate impedance of the power tube 29 is varied in the proper manner to maintain the voltage across the load constant.

The direct current amplifier 6! comprises an electric discharge device 43 which, preferably, is a screen grid vacuum tube, and another electric discharge device 45 which functions as a plate impedance for the first mentioned device 43. In

accordance with a specific feature 0! my invention, the control voltage to the input circuit of the direct current amplifier 4| is supplied from a resistor 41 connected in shunt to the load II.

Obviously, in order to obtain maximum-control, the grid 49 and cathode ll of the vacuum tube 43 should be connected across the entire resistor 41 to apply the total voltage drop of the resistor 41 to the amplifier input circuit. Such a connection, however, would require a very large biasing battery in a system where there is a voltage drop of several hundred volts across the load. Furthermore, a direct current connection across the entire resistor 41 is not necessary in order to obtain the necessary control ior variations in the voltage. v

I obtain the proper control tor the above-mentioned voltage variations and a certain amount of control for the higher frequency or hum variations by conductively connecting the grid 40 and the cathode 5| across a small section of the resistor 41, thus allowing the utilization 01' a comparatively small biasing battery I in the grid circuit.

y The desired additional regulating action for eliminating hum or comparatively high frequency voltage variations is obtained by connecting the control grid 49 and the cathode ll across the entire resistor 41 by means oi coupling condensers 55 and 51, respectively.

, The screen grid 58 of the vacuum tube 43 is supplied with the proper positive potential by connecting it to a point on the resistor 41.

The plate iii of the vacuum tube 43 is connected through the vacuum tube 45, which serves as a coupling resistor to the upper or positive terminal of the resistor 41. This circuit may be traced from the plate ii oi the amplifier tube 43 through a resistor ll to the cathode II of the coupling tube 45, through the space charge path of the tube to the anode B1, and through themductors 69 and 31 to thepositive terminal of the resistor 41.

The screen grid 1| of tube 45 is supplied with a suitable positive potential by means of a battery'13.

The contro1 grid 15 of coupling tube 4! is connected to the upper terminal of the resistor 03 so that the plate impedance of the coupling tube changes with a change in current through the resistor 63. It will be seen that the current flow through the resistor "is in such a direction that it the current flow increases. the grid 1! is made more negative and the plate impedance of the coupling tube 45 increases.

v The plate impedance of the power tube 2! is controlled in accordance with the output or the direct current amplifier 4| by means of the power tube control grid 11 which is connected by means of a conductor 19 to the plate ll or the amplifier tube 43.

The above described circuit provides what may be referred to as negative regeneration, since the direct current amplifier 41 is connected to resist variations in voltage rather than to amplify them. This action will be understood by considerlng the action of the amplifier 41 when the voltage output of the rectifier I increases. Such an increase will cause an increase in current fiow through the shunting resistor 41 and make the control grid 48 of the amplifier tube 48 more positive with respect to the cathode II. This causes an increase in current through the resistor it and coupling tube 45, whereby the plate ll becomes less positive.

Since the control grid 11 of the power tube II is connected to the plate II, it also becomes less positive, that is, more negative, and the impedance of the power tube 28 is increased, whereby any increase in voltage drop across the shunting resistor 41 is opposed. It will be understood that the voltage variation across the load 28 which is permitted by the system is a function of the gain of the direct current amplifier 4|, the voltage variation being decreased by increasing the gain 0! the amplifier.

I! desired, the coupling tube 45 may be replaced by an ordinary coupling impedance, but the gain of the amplifier 4| is increased by employing the coupling tube 45 since the coupling tube impedance increases with an increase in the plate current of tube 43. Also, a screen grid tube with a high negative bias on the grid and a low positive voltage on the plate, as in the case of tube 45, has a very high plate impedance, 0! the order of several megohms, yet the direct current drop across the tube is only a few volts with a plate current 0! cheer two milliamperes. resistor of similar impedance would have a very high voltage drop at the same current and it would be diflicult and expensive to supply the necessary high voltage. I

Although in the circuit shown in Fig. 1 there is very'little drain on the batteries, obviously,

the elimination of all batteries is desirable.

Fig. 2 shows a system in which batteries have been eliminated by utilizing a special glow tube circuit. In Figs. 1 and 2 like parts are indicated by like reference numerals. It will be noted that in Fig. 2 the choke coil 21 of the filter has been omitted, this being feasible when the direct current amplifier or the regulator systemhas a high gain.

In Fig. 2 the direct current amplifier 81 comprises two screen grid tubes and 85. As in Fig. 1, the control voltage for the direct current amplifier II is provided by means or a resistor 81 connected in shunt to the load 23.

A portion of the resistor 81 is shunted by a glow tube I! connected in series with a current limiting resistor I. The glow tube may be any one of the well known types such as a neon lamp. The control grid 83 or the amplifier tube 83 is connected to a point on that portion 01 the resister 81 which is shunted by the glow tube 89, while the cathode is connected to a point between the glow tube 88 and the current limiting resistor ll.

The glow tube It will have a substantially constant voltage drop thereacross so that it supplies a substantially constant biasing voltage in the grid circuit. It will be noted that since the resister 81 and the glow tube 89 are connected in parallel with respect to the rectifier, their voltage drops arein opposition in the grid circuit of the amplifier tube 83.

In one embodiment of my invention, where the voltage drop across the load 23 was 230 volts, the glow tube II had a constant voltage drop or volts thereacross. while the portion of the resistor between the points 82 and 94 had a normal voltage drop of 113 volts thereacross. This supplied the control grid 83 with a negative bias or 3 volts.

The plate 1 of the amplifier tube 83 is connected to the positive terminals of the voltage supply and load through a high resistance unit II. The plate 01 is conductively coupled to the control gridlll of the tube 85. In order to maintain the control grid lli negative with respect to the cathode Ill or tube II, the cathode I08 60 a sistor 41 by means of the coupling condensers is connected to a point on a resistor I99 connected in shunt to the load, which point is positive with respect to the plate 91 and grid I9 I The plate I91 of the tube 99 is connected to the positive terminals of the voltage supply and load through a resistor I99-which may be of the same value asthe resistor 99 in the plate circuit of the other tube. In one embodiment of the invention, resistors 99 and I99 had a value of l megohm.

Obviously, the plate I91 of tube 99 must be at a higher potential than the plate 91 of tube 99 in order that it shall be at a positive valuewith respect to its cathode I99. It is maintained at this higher potential since the plate current of the tube 99 is less than the plate current of the tube 89 due to the control grid Ill of tube 99 always being maintained more negative than the control grid 99 of tube 99.

The screen grid III of tube 99 is supplied with a suitable positive potential by means of a resistor 9 connected in shunt to the load 99, while the screen grid I ll of the tube 99 is supplied with the proper potential. by connecting it to the positive terminal of the power supply through a conductor I I1.

As in Fig. 1, the input circuit of the direct current amplifier 9| has an alternating current connection across the entire resistor 91, this connection being through coupling condensers H9 and I2 I. A strong control voltage will be applied to the amplifier input circuit through the coupling condensers for reducing voltage variations of a comparatively high frequency such as those having a frequency of 60 or 120 cycles.

In Fig. 3, the circuit of Fig. 1 is shown modified for utilizing a voltage control tube connected in shunt to the load instead of in series with it. In the two figures like parts are indicated by like reference numerals.

Referring to Fig. 3, the power tube is shown replaced by a smaller three element tube I29 connected in shunt to the load. It will be seen that the tube I29 acts as a bleeder resistor, the impedance of which may be varied by means of a control electrode I29.

With the valtage control tube I29 in shunt to the load, the phase of the control voltage applied to the control grid I29 must be such that an increase in voltage drop across the resistor 41 causes a decrease in the plate impedance of the tube I29.

In order to get the proper phase relation, the control grid 49 of the amplifier tube 49 is connected below the point I21 on the resistor 41 to which the cathode II is connected. Since this connection would put the control grid 49 at a high negative potential, a biasing battery I 29 is inserted in the grid circuit for maintaining the grid 49 at the proper negative bias. The grid 49 and cathode ii are coupled across the entire re- I9I and I93, respectively, as in l ig. 1.

The impedance of the voltage control tube I29 is controlled in accordance with the output of the direct current amplifier 4i by means of the control grid I29 which is conductively coupled to the plate 9i of the amplifier tube 49. In order to maintain the control grid I29 at a negative potential with respect to the cathode I99, a biasing battery i91 is inserted in the connecting lead between the plate 9i and the control grid I29.

All of the above described circuits have the common features of a resistor connected in shunt to the load for supplying the control volts-so to the direct current amplifier. They also have the common feature of a direct current amplifier which has its input circuit conductively connected across only a part of the voltage control tosistor for opposing slow voltage changes and capacitively connected across the entire voltage control resistor ior opposing voltage hum variations.

Referring to Fig. 4, where parts similar to those in Fig. 2 are indicated by like reference numerals, there is shown a current limiting system which does not require the use of batteries. As in Figs. 1 and 2. a power tube 99 is connected in series with thesource of rectifying current and the load. In this circuit, however, the control voltage is supplied from a resistor I99 connected in series with theload.

The control voltage is applied to the input of a direct current amplifier II which is similar to the one shown in Figure 2.

The main distinction between the circuits Figs. 2 and 4 resides in the input circuit of the direct current amplifier 9i. The cathode 99 of the first amplifier tube 99 is connected to a point on the series resistor I99, while the control grid 99 of the amplifier tube 99 is connected through a conductor I to a circuit in shunt to the rectifier. This shunt circuit comprises a grid glow tube I49 connected in series with a current limiting resistor I49.

With respectto the grid circuit of the amplifier tube99, the glow tube I49 is connected in series relation with the portion of the series resistor I99 which is in the said arid circuit. With respect to the rectifier, however, the glow tube I49 and the series control resistor I99 are connected in parallel. drops across the glow tube I49 and the resistor I99 are in series opposition in the amplifier grid circuit so that thedesired small negative bias is applied to the control grid 99.

It will be noted that the glow tube I49 and the resistor I41, which supplies the desired potential to the screen grid III and the cathode I99, are connected across the power supply at a point between the rectifier i and the power tube 29 instead of at a point between the load 29 and the power tube 29 as in the preceding figures. This is desirable since the voltage across tggoad may be varied greatly in maintaining current through it substantially constant.

In both Fig. 2 and Fig. 4 the glow tube and current limiting resistor may be replaced by a ballast lamp connected in series with a resistor. Since a ballastlamp is a constant current device, the drop across the resistor will be substantially constant and may be utilized in place of the voltage drop across a glow tube. While it is preferred that a glow tube or some other device which has a substantially constant voltage drop thereacross be used, the operation of the circuit will be satisfactory so long as the voltage variation across the glow tube or substituted device is small compared with the voltage variation across the resistor. It will be noted that both the glow tube and the ballast lamp have an impedance which varies with the voltage impressed across them.

From the foregoing description, it will be apparent that I have provided regulating systems which are highly effective in supplying a load with either a constant voltage or a constant current and which are economical and convenient to operate. More particularly, I have provided cer-' tain vacuum tube regulating systems which derive all the voltages for the vacuum tubes from the It will be apparent that the voltage' source of power to be regulated whereby all batteries are eliminated. Also, I have provided certain other vacuum tube regulating systems which require only small biasing batteries which will havea long life.

Various modifications may. be made in my invention without departing from the spirit and scope thereof, and I desire, therefore, that only such limitations shall be placed thereon as are necessitated by the p ior art and set forth in the appended claims.

I claim as my'invention:

i, In a voltage regulating system for a source of variable voltage, a load, a voltage divider resistor shunted across said load, an electric dis- I charge tube having a control electrode, said tube being connected in the circuit between said source and said voltage divider resistor, and means for controlling ,the impedance of said tube in accori iance with changes in voltage drop across said voltage divider resistor, said means comprising a direct current amplifier having an input circuit connected to said voltage divider resistor and an output circuit connected to said control electrode.

2. A system according to claim 1 characterized in that a second circuit including a glow tube is connected in shunt to a portion oi, said voltage divider resistor, said glow tube and said portion being connected in series relation in said input circuit 01' the direct current amplifier.

3. In a voltage regulating system for a source of variable voltage,- a load, a voltage divider resistor shunted across said load, an electric discharge tube connected in series with said source and said load, said tube having a control electrode, and'means for. increasing the impedance of said tube in responseto an increase in current through said voltage divider resistor, said means including a direct current amplifier having its i input circuit'connected across a low potential portioii of said voltage divider resistor and its output circuit connected to said control grid.

14'. In combination, an amplifier comprising an electric discharge device having input electrodes including a control electrode, a source of potential, a constant impedance device connected in series with said source, a gaseous discharge device also connected in series with said source, and means for connecting said impedance device and said gaseous discharge device in series relation between said input electrodes with the voltage in said devices in opposition.

Q5. Apparatus according to claim 4 characterized in that the gaseous discharge device is connected in a circuit which is in shunt to the constant impedance device.

6. Apparatus according to claim 4 characterized in that the gaseous discharge device is a glow tube.

7. In combination, an amplifier comprising an electric discharge device having input electrodes including a control electrode, a source of potential, a variable impedance circuit connected in series .with said source of potential, a portion of said circuit having a constant voltage drop thereacross, an impedance device of comparatively constant impedance connected in a circuit in shunt to said variable impedance circuit, and means for connecting saidimpedance device and a portion of said variable .impedance circuit in series relation between said input electrodes.

8. In combination, a source of electrical energy, a load connected thereto, an electric discharge tube connected in series with said load, a direct-current amplifier having input electrodes and an output circuit, a resistor connected across said load, a circuit including a glow tube connected across at least a portion of said resistor, one of said input electrodes being connected to the portion of said resistor shunted by said glow tube-and the other of said input electrodes being connected to said glow tube circuit, and means for so connecting the output circuit of said amplifier to said electric discharge tube that the impedance of said tube is increased in response to an increase in the voltage of said source.

9. In a voltage regulating system for a source of variable voltage, a load, an impedance device shunted across said load, an electric discharge tube connected in series with said source and said load, said tube having a control electrode, and means for increasing the impedance of said tube in response to an increase in current through .said impedance device, said means including a direct current amplifier having input electrodes and an output'circuit, a circuit including a glow tube connected across at least a portion of said impedance device, one of said input electrodes being connected to the portion of said impedance device shunted by said glow tube and the other oi said input electrodes being connected to said glow tube circuit, said output circuit being connected to said control grid.

10. In a voltage regulating system including a source of variable voltage and a load connected thereacross, an impedance unit connected in shunt to said source, a variable impedance device connected in the circuit between said source and said impedance unit, and means including a direct current amplifier for controlling the impedance of said device in accordance with variations in voltage supplied from said source, said amplifier having input electrodes conductively, connected across a portion 0! said impedance unit, said input-electrodes also being coupled across a larger portion 01 said impedance unit by coupling means which will pass pulsating voltages only.

11. In a voltage regulating system including a source of variable voltage and a load connected thereacross, an impedance unit connected in shunt to said source, a variable impedance device connected in the circuit between said source and said impedance unit, means including a 'directcurrent amplifier for controlling the impedance of said device in accordance with variations in voltage supplied from said source, said amplifier having input electrodes and an output circuit, means for conductively connecting said input electrodes across a portion of said impedance unit, means for capacitatively connecting said input electrodes across a larger portion of said impedance unit, and means for coupling the output circuit of said amplifier to said variable impedance device.

12. In a current regulating system, a source of current, a load connected thereto, an electric discharge tube connected in series with said load, a resistor also connected in series with said load, a glow-tube circuit connected across said source and in shunt relation to at least a portion of said resistor, and means for increasing the impedance of said tube in response to an increase in current through said resistor, said means including a direct current amplifier having an input circuit connected across said glow tube and said portion of said resistor, said glow tube and said resistor portion being in series relation with respect to said input circuit.

13. In combination, a source of voltage, an amplifier having an input circuit including input electrodes, a substantially constant impedance device connected across said source, a gaseous discharge device connected in parallel with said constant impedance device, means for connecting one of said input electrodes to said constant impedance device, and means for connecting the other of said input electrodes to said gaseous discharge device whereby said constant impedance device and said gaseous discharge device are connected in series in said input circuit.

14. In combination, an amplifier comprising an electric discharge tube having input electrodes including a control electrode, a source of potential, a first impedance device connected in series with said source, said first device having a substantially constant impedance, a second impedance device also connected in series with said source, said second device having an impedance which changes substantially instantaneously in response to a change in voltage impressed thereacross, and means for connecting said impedance devices in series relation between said input electrodes with the voltage drops in said devices in opposition.

5 15. A voltage regulating device including a source of current having a pair of terminals, a tube including electrodes and a grid, a conductive connection between one of said terminals and one of said electrodes, a connection leading from the otherelectrode, out-put means for the device connected at one side to the last mentioned connection, a connection leading from the remaining terminal of the source of current, control means for said grid bridged between the last 35 two connections, and a conductive connection between said grid and the controlling means, said controlling means including a discharge gap and a resistor in series with the discharge gap and a contact movable over said resistor and forming a terminal for the last mentioned connection.

16. A regulating circuit for direct currents, said circuit having an input and an output tending to very from normal in accordance with the potential diilerence between the output and input, said 45 circuit including a variable resistance tube,

means for supplying a constant potential, and

means to regulate the resistance of the tube in conformity with variations from normal of the potential difierence between the first means and 5 the output.

17. A voltage regulating device including a source of current having apair of terminals, a tube including electrodes and a grid, a conductive connection between one of said terminals 55 and one 01' said electrodes, a connection leading from the other electrode, out-put means for the device connected at one side to the last mentioned connection, a connection leading from the remaining terminal 01' the source of current, control means for said grid bridged between the last two connections, and a conductive connection between said grid and the controlling means, said controlling means including a discharge gap and a resistor in series with the discharge gap and M a contact in series with said resistor and forming a terminal for the last mentioned connection.

18. The invention as set forth in claim 16, .wherein said constant potential means includes a gaseous discharge device.

18. The invention as set forth in claim 18, wherein said constant potential means comprises a glow tube connected in series with a resistor.

20. The invention as set forth in claim 18,

wherein said regulating means comprises a voltage divider network connected across said output circuit.

21. A voltage regulating device including a source of current having a pair of terminals, 8. tube including electrodes and a grid, a conductive connection between one 01' said terminals and one of said electrodes, a connection leading from the other electrode, output means for the device connected at one side to the last mentioned connection, a connection leading from the remaining terminal of the source of current, control means for said grid bridged between the last two connections, and a direct voltage responsive connection between said gridand the controlling means, said controlling means including a discharge gap and a resistor in series with the discharge gap and a contact movable over said resistor and forming a terminal for the last mentioned connection.

22. A voltage regulating device including a source of current having a pair of terminals, a tube including electrodes and a grid, a conductive connection between one of said terminals and one of said electrodes, a connection leading from the other electrode, output means for the device connected at one side to the last mentioned connection, a connection leading from the remaining terminal of the source of current, control means for said grid bridged between the last two connections, and a direct voltage responsive connection between said grid and the controlling means, said controlling means including a discharge gap and a resistor in series with the discharge gap and a contact in series with saidresistor and forming a terminal for the last mentioned connection.

23. A voltage regulating device includinga source of current having a pair of terminals, a tube including-electrodes and a grid, a conductive connection between one of said terminals and one of said electrodes, a connection leading from the other electrode, output means for the device connected at one side to the last mentioned connection, a connection leading from the remaining terminal of the source of current, control means for said grid bridged between the last two connections, and a direct voltage responsive connection between said'grid and the controlling means, said controlling means including a discharge gap and a resistor in circuit with the discharge gap and a contact movable over said resistor and forming a terminal for the last mentioned connection.

24. A voltage regulating device including a source of currenthaving a pair of terminals, a tube including electrodes and a grid, a conductive connection between one of said terminals and one of said electrodes, a connection leading from the other electrode, output means for the device connected at one side to the last mentioned connection, a connection leading from the remaining terminal oi the source oi current, control means for said grid bridged between the last two connections, and a direct voltage responsive connection between said grid and the controlling means, said controlling means including a discharge gap and a resistor in circuit with the discharge gap and a contact. in circuit with said resistor and forming a terminal for the last mentioned connection.

ARTHUR W. VANCE.

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