US2306378A - Electronic circuit for frequency conversion - Google Patents

Description

Dec. 29, 1942. H. E. BROWN 2,306,378

ELECTRONIC CIRCUIT FOR FREQUENGY'CONVERSION Filed Dec. 27, 1940 INVENTOR. Hue/1 5. BROWN.

A FOR/V573.

Patented Dec. 29, 1942 ELECTRONIC CIRCUIT FOR FREQUENCY CONVERSION Hugh E. Brown, Cleveland Heights, Ohio, assignor to The W. S. Tyler Company Application December 27, 1940, Serial No. 371,857

3 Claims.

This invention relates, as indicated, to an electronic circuit for frequency conversion, but has reference more particularly to a circuit of this character which is especially adapted for controlling the vibrations of industrial vibrating machinery, such as vibrating screens and the like. The invention, further constitutes an improvement over my copending application, Serial No. 357,749, filed September 21, 1940.

A primary object of the invention is to provide a circuit of the character described which will convert alternating current of a commercial frequency, i. e., 60 cycles, into current of a lower frequency, as for example 15 cycles, which is desirable for use in vibrating screens and the like.

Another object of the invention is to provide a circuit of the character described which is characterized by the absence of batteries and of parts which are subject to breakage or are likely to cause difficulty in their operation.

A further object of the invention is to provide a circuit of the character described, which embodies a minimum number of tubes, and makes use of standard tubes which are readily available in the market at fairly low cost.

To the accomplishment of the foregoing and related ends, said invention, then, consists of the means hereinafter fully pointed out in the claims; the annexed drawing and the following description setting forth in detail certain means for carrying out the invention, such disclosed means illustrating, however, but one of various ways in which the principle of the invention may be used.

In said annexed drawing:

Fig. 1 is a schematic diagram of an electrical circuit embodying the novel feature of the invention, and

Fig. 2 is an oscillogram of the voltage waves supplied to the load in the circuit illustrated in Fig. 1.

Referring more particularly to the drawing, the circuit includes a source of alternating current of ordinary public utility voltage, i. e., 220 volts, as represented by the power lines I and 2. A load L is placed in a line 3 which extends from the power line 2. Such load may be the magnet of a vibratory screen, or other load of an inductive character.

The various branches of the circuit are supplied with current by means of a power transformer I, the primary coil 5 of which is connected to the supply lines I and 2, and the secondary of which consists of three coils 6, I and 8. The coil 6 supplies 60 volts at 250 milli-amperes, and the coil 8 supplies 2 volts at 22 amperes where the power tube to be presently described is a C6J tube, and 5 volts at 11 amperes where the power tube is a thyratron power tube.

The main portion of the circuit comprises the line 3, load L, a power tube 9, and a line I0, which connects the cathode I I of the tube 9 with the supply line I. The anode or plate I2 of the tube 9 is connected to the line 3. The cathode II is indirectly heated by current supplied by the coil 8 through wires I3 and I4. The tube 9 is a power tube of the C6J type or a thyratron, and

includes, in addition to the elements II and I2, a grid I5. This portion of the circuit, in the absence of other parts to be presently described would produce rectified current impulses, as designated by the positive impulses A, C, E, G, J, et seq. in Fig. 2, the negative impulses B, D, F, H, et seq. being omitted.

In order to produce 1800 impulses per minute, it is necessary to so modify the action of the aforesaid portion of the circuit as to omit, in addition to the negative impulses B, D, F, H, et seq., the alternate positive impulses C, G, so as to produce for the operation of the load L, only the impulses, A, E, J, etc. For this purpose, a circuit is employed which comprises as its principal parts a #56 triode I6, a small audio-transformer I! having a 4 to 1 or 5 to 1 ratio, a 2 mid. 800 volt paper condenser I8, a 4000 ohm 10 watt resistor IS, a .5 mid. 600 volt paper condenser 20, and a 5000 watt 50 ohm resistor 20'.

The triode I6, consists of a cathode 2|, a grid 22 and an anode or plate 23. The plate 23 is connected to the plate terminal P of the transformer by means of a connection 24, and the grid 22 is connected to the grid terminal G of the transformer through a connection 25. The condenser I8 is connected across the B plus terminal B and the filament terminal F of the transformer. The coil 6 of the power transformer is connected to the terminal B by means of a wire 26 and to the cathode 2I by means of a wire 21. A connection between the wire 21 and the terminal F is made by means of Wires 29 and 30. The cathode 2| is indirectly heated by the coil I through wires 3| and 32. The grid 22 is connected to the grid I5 through a wire 33 and the resistor 20', the condenser 20 and. resistor I9 being connected in series across the lines 33 and 29.

The aforesaid circuit sets up an oscillatory current which yields impulses which, when transmitted to the grid I5 of the power tube, will control passage of current through said tube.

With the parts as described, and connected together in the manner described, the power tube 8 will send 1800 impulses per minute through the load L.

By changing the size of the transformer I! and the condenser I 8, frequencies other than that which has been described can be obtained. By using a larger transformer and a higher capacity condenser, it is possible to obtain very low frequency effects. I have been able, in practice, to obtain in this way one impulse per second.

Other modes of applying the principle of my invention may be employed instead of the one explained, change being made as regards the means and steps herein disclosed, provided those stated by any of the following claims or their equivalent be employed.

I therefore particularly point out and distinct-,

ly claim as my invention:

1. An electron tube control circuit including a source of alternating current, a load circuit connected across said source and including an electron tube having plate, cathode and grid elec trodes, means connecting the plate-cathode circuit of the tube in series with said load circuit, and control means for said tube including an oscillation network comprising an electron tube oscillator having plate, cathode and grid electrodes, means for connecting the cathodes of said tubes together, means connecting the grid electrodes of the tubes together, an audio frequency transformer including two windings, means connecting one winding thereof in series with the plate-cathode circuit of the oscillator tube, means connecting the other Winding of said transformer in series with the grid-cathode circuit of the oscillator tube, one end of each of said windings being connected to the cathode of said oscillator tube, a condenser connecting the cathode-connected ends of said windings and means for energizing the plate-cathode circuits of said tubes and the cathodes of said tubes from said alternating current source.

2. An electron tube control circuit including a source of alternating current, a load circuit connected across said source and including an electron tube having plate, cathode and grid electrodes, means connecting the plate-cathode circult of the tube in series with said load circuit,

and control means for said tube including an oscillation network comprising an electron tube oscillator having plate, cathode and grid electrodes, means connecting the cathodes of said tubes together, means connecting the grid electrodes of the tubes together, an inductance unit having a plurality of coils, means connecting a first coil of said unit in series with the platecathode circuit of said oscillator tube, means connecting a second coil of said unit in series with the grid-cathode circuit of the oscillator tube, one end of each of said first and second coils being connected to the cathode of said oscillator tube, a condenser connecting the cathode-connected ends of said coils, heating means for the cathodes of said tubes, and means for energizing said heating means and the platecathode circuits of said tubes from said alternating current source.

3. An electron tube control circuit including a source of alternating current, a load circuit connected across said source and including an electron tube having plate, cathode and grid electrodes, means connecting the plate-cathode circuit of the tube in series with said load circuit, and control means for said tube including an oscillation network comprising an electron tube oscillator having plate, cathode and grid electrodes, means connecting the cathodes of said tubes together, means connecting the grid electrodes of the tubes together, an iron core inductance unit having a plurality of coils, means connecting a first coil of said unit in series with the plate-cathode circuit of said oscillator tube, means connecting a second coil of said unit in series with the grid-cathode circuit of the oscillator tube, one end of each of said first and second coils being connected to the cathode of said oscillator tube, a condenser shunted across the cathode-connected ends of said coils, a series connected resistor and condenser forming a shunt connection between the connected cathodes and grid electrodes of the tubes, heating means for the cathodes of said tubes, and means for energizing said heating means and the platecathode circuits of said tubes from said alternating current source.

HUGH E. BROWN.

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