US2870396A - Electronic current regulator - Google Patents

Description

Ja'n. 20, 1959 c. H.` JONES ETAL ELECTRONIC CURRENT REGULATOR Filed Aug. 14. -1953 RRR Q .CRN

United States Patent() ELECTRONIC CURRENT REGULATOR Charles H. Jones and John H. Thompson, Pittsburgh, Pa., assignors, by mesne assignments, to the United States of'America as represented by the Secretary of the Navy Application August 14, 1953, Serial No. 376,275

1 Claim. (Cl. 323-4) The invention described herein may be manufactured by or for the Government of the United States of Amero ica for governmental purposes without the payment of any royalties thereon or therefor.

This invention relates to a current regulator for continuous wave magnetrons which transmit information by frequency and amplitude modulation.

Both current and voltage regulators have four essential elements in their circuitry, to wit: (l) An electron tube or regulator tube in series with a load whose impedance may vary; (2) An amplifier for amplifying the corrcctive" signals; (3) An analyzer for observing the voltage or current (depending upon the type of regulation desired); and (4) A reference voltage for comparison with the analyzed voltage.

It has been found that the voltage current performance curves of continuous wave magnetrons are of such a nature that current regulation provides greater stability than voltage regulation. The present invention, therefore, concerns itself specifically with means to regulate the current.

This invention, although not limited to such use, has been designed primarily for use in connection with an airborne type of radar equipment. One of the essential features is the provision of a light, compact, easily operable type of unit which must, consequently, be as free as possible from bulky, space wasting insulation while, at the same time, it must be non-hazardous to the operating personnel.

In order to achieve the above, this circuit is so devised that the positive side of the regulator output is at I ground potential, this characteristic being necessary if the shell or anode of the continuous wave magnetron is to be operated at ground potential. By the use of this circuit, current regulation is possible even with a shorted load zero resistance. The arcing or sparking currents which may occur in continuous wave magnetrons due to g-as within the tube, mismatch of the load, or

inadequate cathode temperature are limited to safe values.

so that the cathode destruction is minimized. In addition, the composite circuit elements are all operated near ground potential. The regulator amplifier, the voltage reference source, the voltage analyzer, and the current regulator are all kept at safe operating potentials above ground (not over 300 volts). The cathode of the regulator tube is near ground potential and the plate is 1000 volts above ground.

It is, therefore, one object of this invention to provide a current regulator for continuous wave magnetrons which is non-hazardous to operating personnel without the necessity of bulky insulation.

Another object of this invention is to provide a current regulator for continuous wave magnetrons which is light, compact and simple to operate.

Other objects and many of the attendant advantages of this invention will be readily appreciated as the saine 2,870,396 Patented Jan. 20, 1959 becomes better understood by reference to the following detailed description when considered in connection with the accompanying drawing wherein:

Fig. l is a schematic diagram of a circuit embodying the invention.

Fig. 2 is a chart showing a regulation curve for a predetermined load current.

Referring now in greater detail to the drawing there is shown a circuit wherein a triode V1 is used to maintain a constant current across the magnetron. The triode V1 is in series with the magnetron which has impressed thereon a direct current voltage from a voltage source B. The positive potential of the voltage applied to the magnetron is grounded at G. The cathode of tube V1 is connected to the anode of the magnetron through resistor R1 so that the magnetron current must ow through V1.

The resistor R1 plus the magnetron are connected in parallel with a voltage divider network which includes resistors R2, R3, R4 and R5, a potentiometer R5 having a capacitor C1 shunted thereacross, and a pair of gas tubes V2 and V3 for regulating the voltage developed across the potentiometer. The potentiometer is connected to the control grid of the pentode V4 through resistor R7, the plate circuit of the pentode having plate resistors R8, R5, R10 and R11. The plate of the pentode is connected to the grid of the tube V1 in order to regulate the bias thereof. A pair of voltage regulating glow tubes V5 and V5 are connected to the screen grid of the pentode V4, the anode of tube V5 being connected to the voltage input through resistors R12, R13, R11, and R15 while the cathode of V5 is at ground potential.

The operation of the system may be understood by assuming that the magnetron impedance decreases slightly. A current increase results from the impedance change and the potential across the resistor R1 increases. This increase in voltage appears on the control grid of the tube V4 which, in turn, decreases the grid to ground potential on the tube V1. This results in an increase of the grid bias on the tube V1 which causes a decrease of the space current. In this way, the increase in the load current is almost eliminated. The screen voltage for tube V1 can be supplied from a low voltage positive supply or it can be connected to the plate at V2. Either variation will eliminate the need for R12, R13, R14, R15, V5 and V5. Another modied form of the circuit is to eliminate the R3, R1 and R5 and connect the cathode of V3 through the dropping resistor R2 to a low voltage negative supply (200 or 300 volts). This completely isolates the entire regulating circuit from the high negative voltage.

A regulation curve is shown in Fig. 2 for a load current adjustment of milliamperes and various load voltages which were obtained by varying the load resistance. The internal effective impedance is greater than 20 megohms.

Obviously may modifications and variations of the present invention are possible in the light of the above teachings. It is, therefore, to be understood that within the scope of the appended claim the invention may be practiced otherwise than as specifically described.

What is claimed as the invention is:

A current regular network for a load circuit having a pair of input terminals said network comprising a high voltage supply source having a positive terminal and a negative terminal; means connecting one of the input terminals of the load circuit to the negative terminal of the supply source; means connecting the other input terminal of the load circuit to ground; a first electron tube having an anode, a cathode, and a control grid; a first resistor; means connecting the anode of Ythe lfirst lectron tube to the positive terminal of the supply source; means connecting the cathode of the first electron tube to ground through the rstresistor; a second electron tube having an anode, a cathode, Yand acontno'lgrid; means coupling the cathode of Atlietrst:electron ytube-.to the control grid of ,thevsecond-electpon ,tuheynieans con necting the cathode of thefsecond electrontuhegtoggrqund; a second resistor; means connecting the anode ,of the second electron tuhe `to the positive terminal ,ofzthe As1 1pply source through the second resistor; and means :also connecting the ,anode Vof the v,second electron wtube to the control grid .of the rst eleotrontube.

References Cited in the le of this patent UNITED STATES PATENTS Harness etal May 17, 1932 Koch Apr. 23, 194() Braden Aug. 6, 1940 Vance Nov. 24, 1942 Bowie f. Feb. 12, 1946 Blum'len Feb. 7, 1950 Gluyas Dec..25, 1951 Evans v..;. -r Nov. 3, 19,53 Meszaros-----.` Dec. 28, 1954 Burdge Dec. V11, -1956

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