US2653251A - Dual voltage regulator - Google Patents

Description

Sept. 22, 1953 M. PETROFF 2,653,251

DUAL VOLTAGE REGULATOR Filed June 22, 1949 651w FQS Patented Sept. 22, 1953 DUAL VOLTAGE REGULATOR Merlin Petroif, Round Lake, 111., assignor to Stewart-Warner Corporation, Chicago, 111., a corporation of Virginia Application June 22, 1949, Serial No. 100,581

4 Claims. 1

The present invention relates to voltage regulating circuits and has for its purpose to provide simple means for the supply of a high direct current voltage and a relatively low direct current voltage, both with a high degree of regulation and from a single source.

In many electronic devices, two separate direct current voltages are required, both of which should preferably have a high degree of regulation. As an example, some apparatus requires plate voltages in one range and screen voltages in another range with a nice degree of control and regulation of both of these direct current voltages. Ordinary control circuits using cold cathode diodes such as a neon or argon tube are satisfactory for many purposes, but are not capable of giving consistent operations at voltages below that at which current flows through the stabilizing tube.

It is one of the objects of the present invention, therefore, to provide a novel dual voltage stabilizing circuit which supplies one voltage at a high range above that at which the stabilizing glow tube ionizes and the other voltage well below this range.

A further object is to provide a novel circuit which accomplishes the above with a minimum of equipment and with a high degree of stabilization and which has a very low apparent impedance in both power supply circuits.

Other objects and advantages will become apparent from the following description of a pre-- ferred embodiment of my invention which is illustrated in the accompanying drawing.

The single figure of the drawing is a diagrammatic representation of one example of a dual voltage regulating circuit embodying the present invention.

Referring to the circuit diagram the specific circuit shown may be considered as supplied with unregulated voltage at about 400 volts D. C. at the terminal 50. The circuit illustrated is for the purpose of supplying from the unregulated 400 volt D. C. source a high range regulated voltage, which in the present instance may be considered as between 175 and 275 volts, and a separate stabilized low range voltage which is adjustable in the present example between 25 and 75 volts, with both of these voltage sources having a low apparent impedance.

In the interest of complete disclosure, specific values will be given for the components in the circuit diagram although it will be appreciated that the circuit shown will operate with a wide variation in these values and with other changes I which will be apparent to those skilled in the art. Also, of course, different electronic tubes may be substituted for those shown.

In the specific circuit illustrated, the unregulated voltage source is connected to the terminal II) which in turn is connected to the plate I2 and screen I 4 of a tube I6 which may be considered as of the 7B5 type. The high voltage terminal [0 also is connected through a 27,000 ohm resistor [8 to one of the plates 20 of a dual triode tube 22, such as a 7P7, for instance. The grid 25 of the 7B5 is connected to the cathode 20 by way of a 500,000 ohm resistor 28 and also to the plate 30 of a 7C7 type tube 32. The cathode 20 of the 735 is also connected to the regulated high voltage output terminal of the circuitindicated at the point 34. This high voltage line is also connected to ground through a 47,000 ohm resistor 36 in series with-a .05 mi. capacitor 38. The ungrounded side of this capacitor is also connected by a line 40 to the cathode 42 and suppressor grid 34 of the tube 7G7 and also to ground through a one-half watt neon or argon regulating tube 46. The high voltage output terminal fit is connected through a 27,000 ohm resistor 53 to a junction point which in turn is connected to a 70,000 ohm variable resistor 52 having a slider 54 connected to the grid 56 of the 707 and an opposite end 53 which forms a junction 60 with a 5,000 ohm resistor 62 leading to ground. She junction 60 is also connected by a line 5d to one of the cathodes 66 of the dual triode 22. The screen 68 of the 707 is connected to the junction 50 between the 26,000 ohm resistor so and the 70,000 ohm resistor 52. The grid 10 of the dual tri-ode 22 which is associated with the plate 20 is connected through a 500,000 resistor 72 to the cathode it on the same side of the tube and to the output terminal 755 of the low voltage supply. This grid '50 is also connected to the plate 73 on the opposite side of the dual triode 22, this plate 73 being associated with the cathode 6G and with a grid at which is connected to the slider 32 of a 20,000 ohm variable resistor 84 connected between the output terminal 76 and ground. All of the heaters in the tubes, indicated b the numeral 86, are energized in the usual manner from a 51%,- volts filament supply. In this circuit the slider E -l of the variable resistor 52 is used for regulating the high voltage potential at the terminal 3 1 while the slider 82 of the variable resistor 8% is used similarly for varying the low voltage at the output terminal 76.

The circuit operates in the following manner.

The tube 46 is a gaseous voltage regulator which provides across its terminals a constant voltage difference which maintains the potential of the cathode 42 of the amplifier tube 32 at a fixed potential irrespective of the voltage applied to the regulator circuit. The tube 32 is operated as a direct coupled D. C. amplifier, the output of which isq inplied to the control grid 24 of the tube l6 which determines the output voltage. The control grid 56 of the tube 32 is at a poten tial which is determined by the setting of the slider 54 and therefore is a definite but variable fraction of the regulated potential between the terminal 34 and ground. Since the resistor 23 in the plate circuit of the tube 32 is large so that the amplification of the grid 55 to cathode 42 voltage is large, it will be seen that as the grid 56 to cathode 42 potential is reduced to less than cutoff to the tube 46 the voltage at the grid 2''; is rapidly reduced. This increases the voltage dro across the tu t a d. r uc the u nut. l a e: T e outp t volt e s ee to b very sensitive to the current in the resistor 28 and this current in turn is very sensitive to h n es he difference n t e potential f ro o the c t e 42 an h r d 55 f the tube 32 which difierence is also sensitive to the output voltage.

An analysis of the above shows that the poten tial on the grid 55, is less than the reference voltage across the tube 46 by an amount which is almost constant and only slightly less than cutoff for the tube 32. This causes the potential at the terminal 34 to be substantially constant since the ratio of the potential of the grid 56 to the. output voltage is determined by the setting of the sli er 54.

Anything which tends to change the output voltage, such as a variation in the input voltage at IE1 or a variation in the load connected to the terminal 34, changes the grid 56, to cathode 42 potential so as to result in a change in the voltage drop across tube l6 so as to tend to keep the output voltage from changing,

The portion of the circuit below the broken line A..A is used to supply the regulated voltage at low potential. In this portion of the circuit, the upper half of the tube 22, that is, the cathode 14, grid and plate 2d, act as a control for the output voltage at. "E6. In other words, the output low voltage depends upon the voltage drop across this portion of the tube. The grid iii to cathode 14 potential determines this voltage drop characteristic and the potential of the grid lil is in turn determined by the amplification of the lower half of the tube. The amplification factor of the lower half of the tube is high because oi the. high value of the resistor H2 in its plate circuit. Inasmuch as the potential of cathode G6 is fixed as a certain ratio of the regulated high output voltage at the point 34 (because of the fixed voltage divider made up of resistors 48, 52 and $32), the potential of the grid 80 is the determining factor in the low voltage control system. This potential is seen to be a function of the regulated low output voltage at terminal 16 the particular ratio being chosen by positioning the slider 82 as desired. Any tendency of the voltage at terminal to fluctuate for any reason is thus seen to be counteracted by a proper change in the voltage drop across the upper half of the tube so as to return the output voltage to the desired potential. Inasmuch as the regulated voltage for the cathode 66 can be far lower than any reierfilwe voltage possible of attainment di- 4 rectly from a glow tube of the type 46, it is apparent that the regulated output voltage at 76 can be but a small fraction of the regulated voltage at 34 if desired.

Having described my invention in connection with one specific embodiment thereof, it will be apparent that variations may be made therein without departing from the spirit and scope of he invent on,- lTh ne of he inv n io r fore, is to be measured by the following claims.

I claim:

1, A. dual voltage regulating circuit adapted to be connected to a source of high direct current unregulated voltage comprising a high voltage input terminal, a; high voltage output terminal, an electron tube. connected between said terminals andyadapted to vary the voltage drop between said terminals according to the potential upon its grid, an amplifier tube adapted to regulate the potential on said grid, said amplifier be ving a athocle and control rid, a v l ge div der con ec ed to. said outp t terminal. a r able ap; o said v lta e divi r necte 0: s id con r l ar d. a cold. cathode gaseous tube on ec ed to said cath d o stab l ze the potential on said cathode, a second output terminal, an l ctron tu e n iecte v be ween a d np e m nal d a second. tp term n to vary the voltage at said output terminal according to the voltage drop of the last said electron tube, the last said electron tube having a control grid to vary the voltage drop across the; last said electron tube according to the potential on the last said grid, a second amplifier connected to vary the potential on the last said grid, said second amplifier having a control grid, a second voltage divider connected to the last said output terminal, a tap on said second voltage divider connected to the last said grid, and a tap on the first said voltage divider at a potential lower than the potential of the first said tap on the same voltage divider connected, to the cathode of said second amplifier.

2. A dual voltage regulating circuit adapted to be connected to a source of high direct current unregulated voltage comprising a high voltage input terminal, a high voltage output terminal, an electron tube connected between said terminals and adapted to vary the voltage drop between said terminals according to the, potential upon its grid, an amplifier connected to regulate the potential on said grid, said amplifier havin a cathode and control grid, a voltage divider connected to said output terminal, a variable tap on said voltage divider connected to said control rid, means to fix the potential on said cathode, a low voltage output terminal, an electron tube connected between one of said high voltage terminals and said low voltage output terminal to vary the voltage at said low voltage output terminal according to the voltage drop of the last said electron tube, the last said electron tube having a control grid to vary the voltage drop across the last said electron tube according to the potential on the last said grid, a second amplifier connected to vary the potential on the last said grid, said second amplifier having a control grid, a second voltage divider connected to the last said out,- put terminal, a variable tap on said second voltage divider connected to the last said grid, and voltage dividing means connected to the high voltage output terminal to. the second amplifier cathode at a potential lower than that fixed on the first said amplifier cathode. v Q

3. A dual voltage regulating circuit adapted to be connected to a source or high direct current unregulated voltage comprising a high voltage input terminal, a high voltage output terminal, an electron tube connected between said terminals and adapted to vary the voltage drop between said terminals according to the potential upon its grid, an amplifier connected to regulate the potential on said grid, said amplifier having a cathode and control grid, a voltage divider connected to said output terminal, a variable tap on said voltage divider connected to said control grid, means to fix the potential on said cathode, a second output terminal, an electron tube connected between one of said high voltage terminals :and said second output terminal to vary the voltage at said second output terminal according to the voltage drop of the last said electron tube, the last said electron tube having a control grid to vary the voltage drop across the last said electron tube according to the potential on the last said grid, a second amplifier connected to vary the potential on the last said grid, said second amplifier having a control grid, :3. second voltage divider connected to the second output terminal, a variable tap on said second voltage divider connected to the last said grid, and means connected to the high voltage output terminal to supply the second amplifier cathode with a fixed potential.

4. A dual voltage regulating circuit adapted to be connected to a source of high direct current unregulated voltage comprising a high voltage input terminal, a high voltage output terminal, an electron tube connected between said terminals and adapted to vary the voltage drop between said terminals according to the potential upon its grid, an amplifier connected to regulate the potential on said grid, said amplifier having a cathode and control grid, a voltage divider connected to said output terminal, a variable tap on said voltage divider connected to said control grid, a cold cathode gaseous tube connected to said cathode to fix the potential on said cathode at the voltage breakdown point of said cold cathode tube, a low voltage output terminal, an electron tube connected between said input terminal and said low voltage output terminal to vary the voltage at said low voltage output terminal according to the voltage drop of the last said electron tube, the last said electron tube having a control grid to vary the voltage drop across the last said electron tube according to the potential on the last said grid, a second amplifier connected to vary the potential on the last said grid, said second amplifier having a control grid, a second voltage divider connected to the last said output terminal, a tap on said second voltage divider connected to the last said grid, and means connected to the high voltage output terminal to supply the second amplifier cathode with a fractional portion of the potential at said high voltage output terminal, said fractional portion being smaller than the breakdown potential of said cold cathode tube.

MERLIN PETROFF.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 2,219,195 Norgaard Oct. 22, 1940 2,268,790 White et a1 Jan. 6, 1942 2,318,644 Tubbs May 11, 1943 2,407,853 smith Sept. 17, 1946 2,461,514 Bowers Feb. 15, 1949 FOREIGN PATENTS Number Country Date 600,516 Great Britain Apr. 12, 1948

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