US2386548A - Apparatus for providing regulated direct current voltage - Google Patents

Description

0R 2,386,548 V f Get. 9, 1945. H, FQGEL 2,386,548

APPARATUS FOR PROVIDING REGULATED DIRECT CURRENT VOLTAGE Filed March 5, 1943 HENRY FOGEL ATTORNEYS Patented Oct. 9, 1945 APPARATUS FOR PROVIDING REGULATED DIRECT CURRENT VOLTAGE Henry Fogel, Brooklyn, N. Y., assignor to Emerson Radio and Phonograph Corporation, New York. N. Y., a corporation of New York Application March 5, 1943, Serial No. 478,076

11 Claims.

For many purposes, particularly for testing radio equipment, it is desirable to have av direct current voltage available which is constant with a high degree of accuracy. For this purpose such devices as storage batteries are unsatisfactory because they are expensive, occupy a good deal of space, require a great deal of servicing, and are sloppy. 'I'he practice therefore is to use a gaseous voltage regulator tube such, for example, as the 874 tube with a suitable circuit and auxiliary tubes to provide such a constant voltage. This has proved satisfactory for such voltages as may be produced with this type of tube. It is subject to the shortcoming, however, that the constant voltage may not be controlled to be lower than the breakdown voltage of the tube, which is ordinarily more than 50 volts. For constant voltages lower than this value it is therefore the practice to use some other voltage source, one usual source being a storage battery despite its shortcomings. However, for low voltages it is necessary to use a bleeder resistance which has a low value of resistance compared to the resistance of the load, in order that variations in the load shall have a minimum effect on the constant voltage source. This, in addition to the other shortcomings mentioned above, is very inefficient, being not only wasteful of current, but requiring more frequent recharging, refilling and replacement of storage batteries.

My invention provides an apparatus and method for producing a constant direct current voltage direct from the alternating current power mains, which voltage may be maintained constant with an accuracy of approximately plus or minus 1/100 of 1%.

A feature of my invention is that it may be used to produce a constant voltage of a desired value from as low as a small fraction of one volt up to as high a voltage as may be produced with the other apparatus now in use.

In the drawing:

Figure 1 is a circuit diagram illustrating one embodiment of my invention in which I use an oscillator for producing a voltage which is rectied and regulated; and

Figure 2 is a circuit diagram of a modification in which I use a 60 cycle voltage from the power mains which is rectified and regulated.

In Figure 1 I employ a power transformer l and a rectifier which may be of the 5YG3 type, and is so marked, together with a power filter to produce the voltages for operating my apparatus from the power mains Just as many electric devices are so operated. I have an oscillator circuit employing a tube 20 which may be of the 6J5 type which produces approximately 2 volts at a desired frequency, which may be, for example, 1000 cycles. This oscillator voltage is supplied to a two-stage voltage amplifier through a 500,000 ohm potentiometer 2 from which the desired amount of voltage of this frequency may be taken off. This alternating current voltage is amplified in the voltage amplifier comprising the two tubes 3 and 4 which may be of the 6SJ7 type, and is then supplied to a power amplifier tube 5 which may be of the 6L6G type. The output of the power amplifier is supplied to a rectifier tube l which may be of the 83 type, or may be of the vacuum or chemical type, where it is rectified. In the rectifier circuit a constant direct current Output voltage may be taken off as from the leads 'l and 8 across a resistor 9. A filter, which is shown as comprising an inductance I0 and condensers Il and l2, filters out any undesired ripple which may be present in the output circuit.

Also in the output circuit is a 500,000 ohm potentiometer I3. The tap to this potentiometer is connected to the grid of an amplifier tube ll which may again be of the 6SJ7 type. 'I'he tap on the potentiometer is adjusted to apply a portion of the desired voltage to the control grid of this tube. This tube amplifies this direct current voltage and the amplied voltage, reve i phase, is applied from its anode to Uloe' grid of the tube 3.

In the cathode lead to the tube I4 is connected a constant voltage I5 of suitable value, illustrated as 1.5 volts. This value may be varied, but whatever value is used, it must remain constant. This constant voltage source may be, for example, a dry battery, or another suitable battery. It is not called upon to yield any current. That which fiows through the voltage source is in the charging direction, so that its life in use will be practically the same or better than its shelf life. If of the secondary type, the batterys life may be of exceedingly long duration as it is recharged in use.

If the constant voltage across the leads 1 8 should tend to change due to variations in load conditions or for any other reason, the voltage applied to the control grid of tube il will change accordingly. For purposes of explanation let us first assume that the voltage applied to the control grid tends to rise. 'I'his will cause increased current to flow through the tube Il and reduce the voltage at the anode of this tube. As the anode voltage is applied to the control grid of the tube 3 this will increase the bias on that tube and therefore reduce vits amplification and change the wave form of the amplified alternating voltage. The net result of these changes will be that less current will flow through the rectifier tube 6 and consequently less current through the resistor 9, and reduce the voltage across the terminals 1-8 to the same constant value it had before.

If the voltage across the terminals 1 8 tends to fall the voltage applied to the grid of tube I4 will be correspondingly reduced decreasing the bias applied to the control grid of tube 3, resulting in increased amplification and changed waveform, thus increasing the current through resistance 9, and raising the output voltage tc its constant value.

In series with the B voltage supply for the apparatus is a resistor I6 and a potentiometer I1, the tap on the potentiometer serving to connect some of its resistance in the cathode lead of the tube 3. This applies a bias to the tube 3 to adjust its amplification for sensitivity control. The greater the amplification of this tube the more accurately the output voltage will be maintained at its constant value despite variations of output load. The degree of control is so great that for maximum sensitivity, as above stated, the voltage may be kept accurate within a plus or minus of fico of 1%.

It is an essential requirement of my system that the amplifier I4 be stabilized. By this I mean that it shall always be so controlled that its amplification shall at all times be constant so that the controlling feed-back voltage applied to its control grid shall always be amplified to the same extent. This is accomplished by providing the highly constant voltage source I5.

The potentiometer I3 not only provides the feedback voltage used to effect the control, but also precludes the necessity for a critical value for the voltage source I5. If this voltage should vary for any reason, all that is necessary is to make a corresponding adjustment in this potentiometer so that a voltage of the same value as that previous to the change is applied to the control grid of tube I4. My system is therefore completely free of the necessity of critical values for any of the elements although maintaining a critical value of the output voltage.

Although I have shown and described in the embodiment of my invention illustrated in Figure 1 an oscillator producing a 1000 cycle wave, it will be obvious that this frequency may be of any value. By using a frequency higher than 60 cycles, I reduce the size of the elements of the lter I0, II and I2, thereby effecting economy. With an even higher frequency, for example 20,000 cycles, the size of these elements may be still further reduced, or they may be eliminated entirely.

It may be convenient in some cases, however, to employ a 60 cycle wave to produce the constant output voltage. 'Ihe circuit diagram for doing this is illustrated in Figure 2. All that is is necessary is to add another low voltage winding I8 to the power transformer and apply this voltage to the tube 3 instead of the oscillator voltage, by simply disconnecting the oscillator 20 at the point marked I9 in Figure 1 and connecting the output of winding I8 to the tube 3 at the point marked I9 on Figure 2. The oscillator is of course taken out of the circuit by also disconnecting the lead to the B voltage supply.

In the embodiments of my invention illustrated I have shown typical tubes, circuits, circuit elements and values which my invention may take and which in Figure 1 was designed to produce a constant direct current output of 3 volts with a current of 1/2 ampere. It will be understood that other tubes, circuits and values may be substituted within the scope of my invention. For example, if more power is needed tubes may be used in parallel, or larger tubes may be substituted with corresponding changes in values as will be understood by those skilled in the art. I do not, therefore, desire to be restricted to the particular embodiments illustrated, but only to the scope of the appended claims.

What is claimed is:

1. A constant regulated direct current voltage supplier comprising a source of alternating voltage, means for amplifying said voltage, a rectifier, means for applying said amplified voltage to said rectifier, a stabilized amplifier, means for deriving a voltage from the output of said rectifier and applying it to said stabilized amplifier, and means for biasing said first amplifier with said amplified derived voltage, whereby the current in said rectifier is maintained constant, and means for deriving a constant output voltage from said rectifier current.

2. A constant direct current Voltage regulator comprising a source of alternating voltage, an amplifier for amplifying said voltage, a rectifier for rectifying said amplified voltage, means for deriving a voltage from the current output of said rectifier, a stable amplifier for amplifying said derived voltage, and means for deriving a voltage from the output of said stable amplifier and controlling the amplification of said first mentioned amplifier and its effect upon wave form of alternating voltage by said voltage.

3. A constant regulated direct current voltage supplier comprising a source of alternating voltage, means for amplifying said voltage, a power amplifier for amplifying the current derived from said amplified voltage, a rectifier for rectifying said current, a resistance in the output of said rectifier for obtaining a constant voltage therefrom, a potentiometer in the output of said rectifier, a stable amplifier, means for supplying a voltage from said potentiometer to said stable amplifier whereby it is amplified therein, means for deriving -a voltage from the output of said stable amplifier, and means for utilizing said derived voltage to control the magnitude and wave form of said alternating voltage.

4. A constant regulated direct current voltage supplier comprising an oscillator, an amplifier, means for applying the oscillator output voltage to said amplifier for amplification therein, a rectifier, means for applying the amplified oscillator voltage to said rectifier for rectification therein, a stable amplifier, means for applying the rectifier voltage to said stable amplifier for amplification therein, means for deriving an output voltage from said stable amplifier, and means for applying said output voltage to said first mentioned amplifier to control the magnitude and wave form of amplified oscillator voltage.

5. A constant regulated direct current voltage supplier comprising a source of alternating current voltage, an amplifier, means for applying said voltage to said amplifier for amplification therein, a rectifier, means for applying said amplified voltage to said rectifier for rectification therein', a stable amplifier, means for applying said rectified voltage to said stable amplifier for amplification therein, and means for applying said amplified rectied voltage to said first mentioned amplifier LMHUH" iied alternating voltage.

6. A constant regulated direct current Voltage supplier comprising a source of voltage, an ampliiier, means for amplifying said voltage in said amplifier, a rectier, means for rectifying said amplified voltage in said rectifier, a stable ampliiier, means for applying a constant bias to said stable amplifier, means for applying to the control grid of said stable amplier a portion of said rectified, amplified voltage, and means for utilizing the output of said stable amplifier to bias the control grid of said rst mentioned ampliiier.

7. The method of providing a constant regulated direct current voltage with apparatus comprislng a stable ampliiier, which comprises amplifying a voltage from which the constant regulated voltage is to be produced. rectifying said ampliiied voltage, amplifying said amplified, rectiiied voltage in said stable ampliiier, and controlling the magnitude and Wave form of alternating voltage appearing at the output of said rst mentioned amplifier by the output of said stable amplifier.

8. The method of producing a constant regulated direct current voltage with apparatus comprising a stable amplifier, which consists in amplifying a voltage from which the constant direct current output voltage is to be derived, rectifying said amplified voltage, applying a constant bias to said stable ampliiier, applying a portion of the rectified, amplified voltage to the control grid of said stable amplifier, and using the output of said stable amplifier to control the gain of said rst mentioned amplifier, as well as its eiect upon Wave form of amplied alternating voltage.

9. A constant regulated direct current voltage supplier comprising a source of unregulated direct current, means for inverting said direct current to alternating current, a source of alternating voltage, means for driving said inverter by said alternating voltage, means for rectifying said ottimi! 9mm alternating current to produce a direct current output voltage, a stable ampliiier, means for amplifying a component of said direct current output voltage in said stable ampliiier, and means for utilizing said amplified component to control the amplitude of said alternating voltage, whereby said direct current output voltage is maintained constant.

10. A constant direct current voltage regulator comprising a source of unregulated direct current, means for inverting said direct current to alternating current, an oscillator, means for amplifying the output of said oscillator, means for driving said inverter by the output of said amplifier, means for rectifying said alternating current to produce a direct current output voltage, a stable ampliiier, means for amplifying a component of said direct current output voltage in said stable amplifier, and means for utilizing said amplified component to control the gain of said iirst mentioned amplifier, whereby said direct current output Voltage is maintained constant.

11. A constant regulated direct current voltage supplier comprising a source of unregulated direct current, means for inverting said direct current to alternating current of a desired frequency, an oscillator operating at the desired frequency, means for amplifying the output of said oscillator in a iirst amplier, means for driving said inverter by the output of said amplier, means for amplifying the alternating current output of said inverter, means for rectifying said alternating current output to produce a direct current output voltage, a stable amplifier, means for amplifying a component of said direct current output voltage in said stable amplier, and means for utilizing said amplified component to control the gain of said first amplifier, whereby said direct current output voltage is maintained constant.

HENRY FOGEL.

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CERTIFICATE OF CORRECTON. Patent No.2,5865J-4B October 9, 19h54.

HENRY FOGE'L It is hereby certified that error appears .in the printedspecifcation of the above numbered patent requiring correction as follows: Page5, first column, line 16, claim 7, forthe word "comprises" read --consists f'|.n-;A line 27, cllim 8, for l'consists in" read -comprises; and that the said Letters Patent should be read withrthis correction thereinthat the same may conform to the record of the case in the Patent Office.

Signed'and sealed this 18th day of December, A. D. 1911-5.

Leslie Frazer (Seal) First Assistsnt Commissioner of Patents.

@ Gfpem cEnTIFIcATE cF onnEcTroN. Patent No.2,536,5b3. octbber 9, 1915.

HENRY FOGEL It: 1s hereby certified that error appears ,in the printed-specification of 121e above numbered patent requiring correction as follows: Page 5, first wlmm, line 16, claim 7, for the word "comprises" read --consists in;. line 27, claim 8, for "consists in" read -comprises; and that the said Letters Patent should be read withtthis correction thereizfthat the same may conform to the record of the 'case in the Patent Office.

Signedand sealed this 18th day ofubecembez', A. D. 1945.

Leslie Frazer` (Seal)- First Assistant Commissionerof Patents.

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