US2536830A

US2536830A - Electronic regulator circuit

Info

Publication number: US2536830A
Application number: US51801A
Authority: US
Inventors: Garret F Ziffer
Original assignee: General Electric Co
Current assignee: General Electric Co
Priority date: 1948-09-29
Filing date: 1948-09-29
Publication date: 1951-01-02
Anticipated expiration: 1968-01-02

Description

Jan. 2, 1951 G. F. ZIFFER 2,536,830

ELECTRONIC REGULATOR CIRCUIT Filed Sept. 29, 1948 Inve t or' Garret F Z Ffer;

H Hwg ALLO "N89 Patented Jan. 2, 1951 ELECTRONIC REGULATOR CIRCUIT Garret F. Ziil'er, Syracuse, N. Y., assignor to General Electric Company, a corporation of New York Application September 29, 1948, Serial No. 51,801

4 Claims.

This information relates to electrical regulator circuits and more particularly to regulating systems employing electronic valves as the control elements.

It is an object of this invention to provide a new and improved electronic regulator, having no moving parts, which will maintain a unidirectional output voltage or current constant within narrow limits in spite of wide variations in the magnitude of the input voltage.

Another object of this invention is to provide an improved regulator whose output is substantially unail'ected by the frequency of amplitude variations or of ripple components in the input voltage.

A further object of this invention is to provide an improved electronic regulator circuit which can readily be utilized to provide a constant negative potential from a, negative input voltage subject to large variations in magnitude.

For additional objects and advantages and for a better understanding of the invention, attention is now directed to the following description and accompanying drawings, and also to the appended claims in which the features of the invention believed to be novel are particularly pointed out.

In the drawings:

Fig. 1 and Fig. 2 are generalized circuit diagrams, including voltage and current vectors, for

the purpose of facilitating an exposition of the principles of my invention;

Fig. 3 is a schematic illustration of a current regulator embodying my invention; and

Fig. 4 is a schematic illustration of a potential regulator also embodying my invention.

In accordance with my invention, a pentode electronic valve is serially connected between a source of variable voltage and a utilization circuit. The utilization circuit may be a network through which a constant current is required to flow. Or, again, it may be a potentiometer across which a constant voltage is developed and which may be tapped at any point to give a constant potential. Since the anode resistance of a pentode valve is very high, the current through the valve is largely independent of the anode voltage, and is substantially a function of the voltages on the control electrodes alone. Considering the control grid and the screen grid of a pentode valve as the control electrodes, the anode current through the valve is dependent only upon the control grid and screen grid voltages, within certain limits of anode voltage. In accordance with my invention, the screen grid and control grid voltages are derived from a common source and are applied in magnitudes inversely proportional to the effect of the screen grid and control grid respectively on the electron current, and in polarities such that one counteracts the effect of the other. Accordingly, a change in the source voltage will cause a change in the voltage on one control electrode which will be canceled out by the corresponding change on the other electrode. As a result, the anode current flowing through the valve and through an output device connected in series with the valve will remain constant in spite of changes in the :magnitude of the source voltage.

The principles of operation of my invention will be better understood by referring to Figs. 1

and 2 in which there is shown schematically a to the junction of resistances R2 and R3, and its control grid connected to the negative terminal of the source. In the equivalent circuit diagram of Fig. 2, the valve V1 is conventionally represented as a generator and, to simplify the diagram, the connections to the electrodes are not shown.

The symbols shown have the following significance:'

Eb=voltage generated by the source B. E=cathode to control grid potential. Es=cathode to screen grid potential. i ==current circulating through valve V1. i1=current circulating through the source B.

The circuit parameters comprising resistances R1, R2, R3 maybe chosen in such a manner that a change in the screen grid voltage Es, caused by a change in the source voltage Eb, has its effect on the anode current i Just canceled out by the corresponding change in the control grid voltage E3. The anode to cathode potential will also change due to the change in source voltage Eb, but this has an entirely negligible efiect on the anode current in a pentode. As a result, the anode current is independent of any change in the source voltage within wide limits. If this current flows through a resistance, such as R4. the voltage developed across it will also remain practically constant. Accordingly, the circuit can be utilized as a current regulator, by locating AE -R, RI+RI+RI b' l i+R:+ l Dividing Equation I by Equation II:

The ratio is equal to the amplification factor at of the valve when the latter is connected as a triode, or in other words to the amplification factor of the control grid with respect to the screen grid. This is the amplification factor of the valve when the anode and the screen and suppressor grids are connected together to constitute effectively a single anode, and the control grid is employed as the single control electrode. Accordingly, by selecting resistances R2 and R1 so as to have this ratio,

the necessary condition for maintaining the plate current i constant in spite of variations in the source voltage Eb will be achieved.

The following equation may be used to calculate the actual values of the circuit elements in designing an operating regulator.

Referring to Fig. 3, there is shown an embodiment of my invention for use as a current regulator. The circuit comprises three resistors l3, I4, and connected between a pair of input terminals l0, these resistors corresponding respectively to R1, Ra, Ra of Fig. 1. The regulation is provided by a pentode valve l2 having its cathode and suppressor grid 23 connected to the junc- 'tion of resistors l3 and I4. Its control grid 2| is connected to the junction Of resistor l3 and the negative input terminal, its screen grid 22 is connected to the junction of resistors I4 and I5, and its anode 24 is connected to the negative output terminal II. The positive output terminal I! is directly connected to the positive input terminal II. By selecting resistors l4 and I3 such that the ratio of their resistances is equal to the amplification factor of the control grid of the valve with respect to the screen grid, the output current flowing through a circuit connected to the output terminals II will remain constant in spite of large variations in the amplitude of the input voltage, and in the value of load impedance.

. This regulator circuit is equally effective in reducing the magnitude of ripple components in the output current. In addition it has the advantage that the output current is practically independent of the resistance of the output circuit within wide limits. This feature is inherent in the operation of the regulator due to the fact that current flowing through a pentode valve is practically independent of the voltage applied to the anode and is substantially a function of the control grid and screen grid potentials alone.

Referring to Fig. 4, there is shown another embodiment of my invention in a constant potential circuit. The circuit elements are connected in the same manner as in Fig. 3 except that a potentiometer i6 is connected between the anode ,of the valve ii to the positive output terminal II which is grounded. The negative output terminal I I is connected to an adjustable tap H on the potentiometer It. The regulated output voltage is available at terminals H and due to the constant current flowing through potentiometer ii, the potential available at terminals II will remain constant for any one setting of the tap in spite of large variations in the input voltage. This embodiment provides a negative source of constant potential, since the regulation of the output voltage is with respect to the positive terminal of the supply, rather than with respect v to the negative terminal.

In a particular construction of a voltage regulator in accordance with the embodiment of Fig.

With the tap on the potentiometer adjusted to provide 2 volts D.-C. output, the ripple component in the output was less than .075% and the output voltage varied less than 0.5% when the input voltage varied to the extent of 50%.

This voltage regulator is particularly suitable for use in electronic circuits for providing bias voltages and small negative voltages for clamping circuits. Previous methods of generating such small negative voltages have generally utilized a battery or several voltage regulating valves with unidirectional current amplifiers. The use of a battery has the obvious disadvantage of requiring frequent renewal of the battery, while the use of several voltage regulator tubes, as practiced in the prior art, is comparatively very expensive. A voltage regulator providing a small negative voltage, in accordance with my invention, has the obvious advantages of simplicity, reduced cost, and better regulation.

While certain specific embodiments have been shown and described, it will, of course, be understood that various modifications may be made without departing from the invention. For instance, it is possible to use various voltage dropping combinations to provide the necessary voltages in the required proportions to the control electrodes. The appended claims are, therefore, intended to cover any such modifications within the true spirit and scope of the invention.

What I claim as new and desire to secure by Letters Patent of the United States is:

1. In combination, an electronic valve, a source of voltage and a load, said valve having an anodeto-cathode current path connected serially between said source and said load, said valve having first and second control electrodes and being of a type in which the anode current is a function of the voltages on said control electrodes and is substantially independent of the anode 18 voltage, and means to apply a first positive fraction and a second negative fraction of said source voltage to said first and second control electrodes respectively, said "fractions having a ratio substantially equal to the recprocal of the ratio of the effects ,of said first and second control electrodes on said anode current, whereby a variation in the voltage or said source causes the voltages on said control electrodes to change in opposite directions and to maintain said anode current constant.

.2. An electronic regulator circuit comprising a pair of input terminals and a pair of output terminals, an electronic valve having a cathode, an anode and a plurality of control electrodes, a direct connection between one input and one output terminal, a first resistor connecting the other input terminal to said'cathode, a direct connection between said other input terminal and a first control electrode, a second resistor connecting said cathode to a second control electrode, a third resistor connecting said second control electrode to said one input terminal, and a connection from said anode to the other output terminal, sa'd second and first resistors being selected to have a ratio of resistances substantially equal to the amplification factor of said first control electrode with respect to said second control electrode.

3. An electronic regulator circuit comprising a pair of input terminals and a pair of output terminals; a pentode electronic valve having a cathode, an anode, a suppressor grid, a screen grid, and a control grid; a direct connection between one input and one output terminal; a first resistor connecting the other input terminal to said cathode and to said suppressor grid; a direct connection between said other input terminal and said control grid; a second resistor connecting said cathode to said screen grid; a

third resistor connecting said screen grid to said one input term'nal; a connection from said anode to the other output terminal; and a load impedance connected between said output terminals; said second and first resistors being selected to have a ratio of resistances substantially equal to the amplification factor of said control grid with respect to said screen grid.

4. An electronic voltage regulator for providing a regulated negative potential with respect to a point of reference potential from a source of potential negative with respect to said point, comprising an input terminal and an output terminal; first, second, and third resistors serially connected between said input terminal and said point; a pentode valve having a cathode, an anode, a grid, a screen and a suppressor; a direct connection from said input terminal to said grid; a direct connection from the junction of said first and secondresistors to said cathode and to said suppressor; a direct connection from the junction of second and third resistors to said screen; a fourth resistor connected between said anode and said point; and a connection from a point on said fourth resistor to said output terminal, said second and first resistors being selected to have a ratio of resistances substantially equal to the amplification factor of said control grid with respect to said screen grid.

GARRE'I F. ZIFFER.

REFERENCES CITED The following references are of record in the file of this patent: