US2444472A - Voltage regulator circuit - Google Patents

Description

July 6, 1948- A. H. SCHOOLEY VOLTAGE REGULATOR CIRCUIT Filed June 19, 1943 nsauafzo ourPur LE'ii-E gvwwwbo'b ALLEN H. SCHOOLEY Patented July 6, 1948 UNITED STATES PATENT OFFICE VOLTAGE REGULATOR CIRCUIT Allen B. Schooley, Washington, D. 0.

Application June 19, 1943, Serial No. 491,470 1 Claim. (01. 323-89) (Granted under the act oi March 3, 1883, as

amended April 30, 1928; 370 0. G. 757) This invention relates to a voltage regulator and more particularly to a means for stabilizing the output from a line controlled transformer.

In many of the current radio circuits voltage regulation is of prime importance since minute voltage changes may effect the operating characteristic of the entire circuit. Most voltage regulators provided by the prior art relate to B supply and bias regulation. Filament voltage regulation, however, is also of primary importance since changes in filament voltage will also effect the operating characteristic of the vacuum tubes in the circuits.

It is therefore, an object of this invention to provide a voltage regulator for use in controlling the output of a transformer.

It is another object of this invention to provide a filament voltage regulator.

It is another object of this invention to provide a voltage regulator which is equally responsive at all frequency changes.

Other objects and features of the present invention will become apparent upon a careful consideration of the following detailed description when taken together with the accompanying drawings, the figures of which are designed for the sole purpose of illustration and not as a definition of the limits of the invention, reference being had for the latter to the appended claim,

Fig. 1 is a schematic diagram of a preferred embodiment of the present invention, and

Fig. 2 is a schematic diagram of one modification of the present invention.

It is contemplated by the present invention to provide a means for regulating the output of a transformer by utilizing the change in output voltage to control the exciting current of the transformer, and more particularly to control the impedance in the primary circuit of the transformer. The manner in which I propose to accomplish the foregoing is through the utilization of the output voltage from the transformer as a control means for regulating the thermionic emission of a vacuum tube and consequently the conductivity of the tube, which in turn operates to control a serially connected impedance in the primary circuit of the transformer.

Reference is had more particularly to Fig. 1 wherein there is shown a preferred embodiment of the present invention, comprising a transformer ID the output voltage of which it is desired to regulate, having a pair of input terminals II and II and a pair of output terminals l2 and I2. Across this latter pair of terminals there is connected a filamentary heater it of the diode H, which in turn contains a, serially connected resistance I! for use in regulating the heater current. The primary winding of a second transformer I3 is connected in shunt with the heater I, while one side of the secondary winding thereof is connected to one of the output terminals l2 and the other side through resistance I! to the plate of diode I4. The latter connection provides the plate of diode H with a pulsating positive voltage. As shown in the Fig. 1 the output of diode I4 is fed to the control electrode 2| of the first tube I9 of a pair of serially comiected direct coupled amplifiers l9 and 20. Since these amplifiers are direct coupled they are equally responsive at all frequencies. The output of this direct coupled amplifier circuit is fed in parallel to the respective control electrodes 25 and 26 of the tubes 2i and 22. The plates of these last two mentioned tubes are connected in push-pull by way of the secondary winding of transformer 23, the primary winding of which is serially connected to the primary winding of transformer ll. A source of plate potential for the direct coupled amplifier circuit comprising tubes l9 and 20 is supplied at 28.

Normal operation of the circuit is as follows: Resistance I1 is regulated to run heater IS a little colder than usual 1. e. a predetermined amount below rated heater voltage so as to draw 9. normally fixed plate current and produce the desired voltage drop across resistance 18. This voltage drop provides a source of input to tube l9 and consequently produces the desired bias for the control electrodes 25 and 26 of tubes 2| and 22 by virtue of the amplification of the direct coupled amplifier circuit. The bias on the last mentioned tubes controls the current passage through these tubes and consequently the load on the secondary winding of transformer 23. The load on the secondary of this transformer is reflected to the primary winding thereof to sustain the desired exciting current in transdrop across the primary winding of the latter in response to the impedance reflected by trans-' former 23 which in turn is under control of the thermionic emission of the diode heater I6.

I have found that the thermionic emission of diode I4 is very responsive to slight changes in heater voltages especially when the diode heater is operated slightly colder than normal as in the present instance. Thus let it be assumed that for some reason an increase in output voltage is occasioned. which increases the thermionic emission of heater l3 and thereby increases the voltage drop across resistance II. This increase in voltage drop appears as a negative bias to the control electrode 24 of tube It which causes the plate voltage of this tube to rise and consequently the plate voltage of tube III to drop. The drop in plate voltage of tube 20 appears as a negative bias to the control electrodes 25 and 28 of tubes II and 22 to decrease the current flow through thesetubes which in eflectproduces a decrease in load on the secondary of transformer 23. The decrease in load of the secondary is refiected'into the primary winding of this transformer as a high impedance to reduce the exciting current or transformer iii and consequently decrease the output voltage thereof. Thus if a decrease in output voltage was occasioned the reverse action of the amplifier circuit and tubes 2i and 22 would result to cause an increase in exciting current to transformer Ill and consequently an increase in output voltage therefrom.

The operation of the circuit shown in Fig. 2 is identical to that circuit shown in Fig. 1, with the exception that this circuit involves the use of an additional transformer 21, and the resistance II is made variable in order to regulate the input to the amplifier circuit and hence the magnitude of the bias voltage supplied to tubes 2| and 12. Therefore, further explanation of this circuit is believed to be unnecessary.

Although I have shown and described only certain and specific embodiments of the present invention, I am fully aware of the many modifications possible thereof. Therefore this invention is only to be restricted except insofar as is necessitated by the prior art and the spirit of the appended claim.

The invention described herein may be manufactured and used by or for the Government of the United States of America for governmental purposeswithout the payment of any royalties thereon or therefor.

I claim:

A means for regulating the output voltage of a transformer, comprising a thermionic vacuum tube having a filamentary heater and a plate, said heater connected across the output terminals of said transformer in such a manner that its thermal emission varies in accordance with the change in output from said transformer, a resistance means disposed in series with said heater and adjusted to operate said heater at a predetermined value below its rated voltage, an amplfier circuit, means connecting the output of said vacuum tube to the input of said amplifier circuit, a pair of electron discharge devices each having an anode, a cathode and a control electrode, a sec- REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,935,413 Prince Nov. 14, 1933 Philpott Jan. 5, 1937

Images