US1942551A - Power supply system for electron tube systems - Google Patents

Description

Jan. 9, 1934. E. R. HENTSCHEL 1,942,551

POWER SUPPLY SYSTEM FOR ELECTRON TUBE SYSTEMS 4 Filed Aug. 9, 1930 2 Sheets-Sheet 1 INVENTOR.

BY 6 G A TTORNE Z JEE -1 Jan. 9, 1934. E, R HENTSCHEL 1,942,551

POWER SUPPLY SYSTEM FOR ELECTRON TUEE SYSTEMS Filed Aug. 9, 1930 2 Sheets-Sheet 2 BY 6 35 W ATTORNJ.

I II I j v 14 1mm? fg/ INVENTOR.

Patented Jan. 9, 1934 UNITED STATES PATENT OFFICE Ernest R. Hentschel, Washington, D. 0.; John Olson,

administrator of said Ernest R.

Hentschel, deceased, assignor to Wired Radio,

Inc., New York, N. Y. ware a corporation of Dela- Application August 9, 1930. Serial No. 474,207

Claims.

My invention relates broadly to electron tube circuit arrangements and more particularly to a method for reducing the effects of fluctuations in the power supply for an electron tube.

One of the objects of my invention is to provide means for eliminating the noise and ripple incident to the supply of power to an electron tube from an alternating current supply system.

Another object of my invention is to provide means for balancing out the hum or ripple of alternating current when supplied to the circuits of an electron tube in a radio receiving or transmitting system.

' Still another object of my invention is to provide a circuit arrangement between the sections of a filter in a power supply circuit for electron tubes and the several output circuits of a number of tubes in cascade, whereby the ripple or hum of the alternating current may be balanced out.

A further object of my invention is to provide a circuit arrangement for a multiplicityof electron tubes connected in cascade, whereby the several circuits may be coupled to the power supply system in such manner that the effect of hum or ripple which may be present in the power supply system, energized from a source of rectified alternating current, will be balanced out, and the effects of such ripple or hum from the electron tube circuit rendered substantially negligible.

A still further object of my invention is to provide a method for progressively tapping a filter system in a power supply circuit for electron tubes, and supplying power to the output circuit of the several electron tubes, in such manner that ripple or hum present in the power supply system will be balanced out by the operation or reaction of the several circuits one upon another.

Other and further objects of my invention reside in a system of connections for a sectionalized filter system in a power supply circuit for a multiplicity of electron tubes whereby tap connections may be taken to the successive plate circuits of the electron tubes from the filter in such manner that hum or ripple existing in the power supply system will be balanced out in the tube circuit and the effects thereof rendered substantially negligible, all as will be pointed out in the specification hereinafter following, by reference to the accompanying drawings, wherein:

Figure 1 diagrammatically shows a radio receiving system employing the circuit arrangement of my invention; Fig. 2 is a theoretical diagram showing the characteristics of the energy in the several parts of the circuit according to my invention; Fig. 3 shows a modified form of amplification circuit having power supply to the several circuits in accordance with the principles of my invention in such manner that ripple and hum may be balanced out and rendered negligible with respect to the operation of the circuit in a quiet manner; and Fig. 4 shows the application of the principles of my invention to a radio transmitter circuit.

My invention is directed to a method of making connections in the audio frequency circuits of a radio receiver or similar device, so as to cause the ripple due to imperfectly filtered plate supply current to be balanced out.

Figure 1 shows such a circuit. Ninneral 11 refers to the alternating current supply line, 12 is a full wave rectifier to which the filter system 20 is connected; tube 1 is the radio frequency amplifier; tube 2 the detector, using a heated cylinder as cathode; and tubes 3 and 4 are audio frequency amplifiers. The plate connection 16 goes to the point 16a on resistance 15, and the plate connections of tubes 3 and 4 go to points 14 and 13, respectively, on the filter 20. The filter includes series connected impedances 21 and shunt connected impedances 22. The output of detector tube 2 is coupled to the input of the first audio frequency amplifier stage 3, through transformer 23. The second audio frequency amplifier stage 4 is coupled through transformer 24, with the output of the first audio frequency amplifier stage 3. Transformers 23 and 24 must be connected in such manner that the ripple which is transmitted from the plate of a, preceding tube to the grid of a succeeding tube, will be at 180 phase relation with the ripple in the plate circuit. The direction of winding of the primary and secondary windings is, therefore, highly important.

In making a general explanation of the theory of my invention, tubes 1 and 2 only will be considered. Fig. 2 shows the comparative amounts of ripple present in the plate supply of the varione tubes, the supply of tube 2 having the least, because its plate supply is tapped off from the point 160:, which is the least ripple point on the filter. At the instant of time ii in Fig. 2, the voltage on the plate of tube 2 is maximum and, therefore, the current is also a maximum. Curve E 13 represents the ripple present in the circuit of tube 4. Curve E 1 1 represents the ripple present in the plate circuit of tube 3, while curve E 16 represents the ripple present in the plate circuit of detector tube 2. As this ripple is an alternating current component, it will be transferred from the plate circuit of tube 2 to the grid of tube 3 by transformer 23. This transformer is so constructed that at the instant 131, this ripple voltage on the grid of tube 3 is at a minimum. This is controlled by winding the secondary in the proper direction with respect to the primary. If it is wound in the other direction, the action will be similar to that of an auto-transformer, and then the grid of plate 3 would be at a maximum potential at the instant mentioned above. This condition will be considered later. If it is wound as first mentioned, the grid of tube 3 is at a minimum, or in other words, at a maximum negative potential and therefore tends to reduce the plate current of tube 3. However, at this same instant the voltage of the plate supply is at a maximum, which tends to increase the plate current. If the values of the inductances and capacities of the filter are correctly proportioned, these tendencies will be equal, and therefore will balance one another and a smooth direct current will fiow in the plate of tube 3. On account of the amplification within the tube, the smallest ripple must be supplied the first tube. Therefore, the plate supply of tube 3 is taken at 14, which, as can be seen in Fig. 1, is not as well filtered as that of tube 1. Thus it can be seen that any number of pairs of tubes could, as far as this bal- I ance is concerned, be cascaded, the second tube of each pair bucking out the ripple picked up by the first. The ripple transferred from the plate of tube 2 or from the primary of transformer 23, to the secondary of transformer 23 and then to the grid of tube 3, is transferred at increased amplitude into the plate circuitof tube 3, so that at the instant of maximum potential on the plate of tube 2, this amplified alternating current component is at a minimum in the plate of tube 3, at which instant the ripple on plate 3 obtained from the tap 14 of the filter system, is at a maximum and therefore, the two components tend to neutralize one another.

If three tubes are cascaded, as is usually done, using a detector and two stages of audio frequency amplification as shown in Fig. 1, the first two must be unbalanced in such direction that tube 4 will complete the balance and supply smooth current to the loud speaker 7. This would be accomplished in Fig. 1 by causing the ripple supplied to the plate of tube 3 by the filter to overbalance that supplied through the grid from tube 2. This could be done by making the filter inductance 21 between points 13 and 14 smaller. Another method would be to reverse the direction of winding of the secondary of transformer 23, making it an auto-transformer. Either of these methods causes the ripple of the first two tubes to add, so that the ripple in the last tubes plate supply must be great enough to balance this large value of ripple supplied the grid; therefore the plate of tube 4 taps the filter at point 13, at which point the current is poorly filtered. As

before, the values of the filter constants are to be correctly adjusted.

In 3 is shown the action in a resistance coupled amplifier. At time ti, as before, the voltage on the plates of the tubes is at a maximum. Therefore the ripple voltage at the upper end of resistance 26 will be positive, which will induce a negative potential across condenser 42 on the grid of tube 3, which will tend to decrease the current in the plate, and oppose the increase due to the ripple from the plate supply, as in Fig. 1.

In all cases the connections are to be made so that the last tube, which may be a power tube, has its plate supply tapped nearer the rectifier than the others, so as to receive the highest electro-motive' force. In this manner the resistances of the filter coils serve as part of a potentiometer in regulating the voltages. Although alternating current filament tubes are shown, direct current filament tubes may also be used. Shield grid tubes may also be employed.

This method can be supplied to any audio frequency circuits, such as public address systems and broadcast station audio frequency amplifiers. It will be applicable to radio frequency circuits, such as transmitters in particular, if the coupling between stages is of a type which will transfer low frequencies. If not, the same results may still be obtained by means of the connections shown in Fig. 4. This is a conventional circuit except for the insertion of audio frequency transformer 17, which transfers the low frequency voltage variations on the plate of tube 13 to the grid of tube 19., in the same manner as trans formers 23 and 24, explained with reference to i Fig. 1. cause it is not necessary to go back further than one tube to pick up the bucking electromotive' force. It will be observed that the filter 36 including elements 31 and 32 are tapped at 34 for 7 connection to the plate of tube 19 as compared with the tap 35 on potentiometer 36 for supplying bucking ripple potential to the plate, of tube 18. If the transmitter is a broadcasting one, the

method just described may be used in the radio 3 frequency part, and the first method described may be used in the modulator, or because of the fact that the last radio frequency amplifier plate is connected in parallel with the modulating plate, the balancing apparatus may be omitted in the radio frequency amplifier. A little more ripple could be fed to the modulator grid so that the ripple produced in the plate would be s'ufiicient to balance the plate supply ripple of both the modulator and radio frequency amplifier.

The modulator tube is not shown, but its plate system, the bucking action being progressively.

applied to the circuits of tubes. arranged in case. cade.

While I have described my invention in certain preferred embodiments, I desire that it be understood that modifications may be made and that no limitations upon my inventionfarein tended other than are imposed by the scope of, k

the appended claims.

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

1. in combination with a cascade arrange; ment of electron tubes, apower supply system 1 The opposition effects are obtained Only the last two stages are shown bee therefor comprising a source of rectified alternating current, a multi-section filter connected with said source, a potentiometer connected across the output of said multi-section filter, and means for fixing the magnitude and the phase of the ripple currents supplied to the respective anodes of said electron tubes so as to substantially annul ripple noises in the output circuit of the last stage of said cascade arrangement, said means comprising tap connections on said potentiometer to the anode circuits of selected tubes and independent tap connections from individual sections of said multisection filter remote from said potentiometer to the anode circuits of others of said electron tubes.

2. In combination with a cascade arrangement of electron tubes, a power supply system therefor comprising a source of rectified alternating current, a multi-section filter connected with said source, a potentiometer connected across the output of said multi-section filter, and means for introducing ripple currents into each of the anode circuits or" said tubes directly proportional to the relative amplitude of the variable currents in the anode circuits of said electron tubes and for fixing the phase of the ripple currents in opposition to one another in the circuits of adjacent tubes so as to substantially armul the ripple noises in the output circuit of the last stage of said cascade arrangement, said means comprising tap connections on said potentiometer to the anode circuits of selected tubes and independent tap connections from individual sections of said multi-section filter remote from said potentiometer to the anode circuits of others of said electron tubes.

3. In combination with a plurality of electron tubes coupled to one another for the progressive amplification of variable currents, a power supply system comprising a source of rectified alternating current, a multiple-section filter connected to said source, a potentiometer connected across the output of said filter and means for fixing the magnitude and phase of the ripple currents introduced into the anode circuits of the respective tubes so as to substantially annul the audible effects of fluctuations in said power source as obtained in the output circuit of the tube in the last stage, said means comprising tap connections on said potentiometer to the anode circuits of selected tubes and independent tap connections from individual sections of said multi-sctio'n filter remote from said potentiometer to the anode circuits of others of said electron tubes, the tap connection to the filter section nearest said source being connected to the anode circuit of the tube in the last stage while the tap connection from the section of said filter circuit next adjacent the source is connected to the anode circuit of the electron tube subject to amplification currents of next smaller amplitude to that of the last stage.

4. In the application of rectified alternating current to a system of electron tubes connected in cascade, where the source of said current comprises a filter circuit and a potentiometer connected to the output thereof, the method of introducing opposing ripple currents into the circuits of said electron tubes which comprises tapping said potentiometer at such points as to obtain plate potentials for successive tubes with respectively increased magnitudes of the ripple component accompanying each said plate potentials, suitably fixing the amplification ratios as between successive stages of said system of electron tubes in accordance with the respective magnitudes of said ripple components and arranging the phase angle of the ripple effect in the output circuit of one tube so as to balance out a greater ripple effect in the output circuit of a succeeding tube.

5. In the application of rectified alternating current to a system of electron tubes connected in cascade, where the source of said current comprises a network having individual filter sections disposed progressively therein and a potentiometer connected to the output thereof, the method of introducing opposing ripple currents into the circuits of said electron tubes which comprises tapping said network and said potentiometer at such points as to obtain anode potentials With graded magnitudes of the ripple component accompanying each said anode potential, suitably fixing the amplification ratios as between successive stages of said system of electron tubes and arranging the phase angle of the ripple effeet in the output circuit of one tube so as to balance out a greater ripple effect in the output circuit of a succeeding tube.

ERNEST R. HEN'ISCHEL.

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