US2075218A - Device for removing undesirable frequencies from electric circuits - Google Patents

Description

March 30, 1937. MIYAZAK, 2,075,218

DEVICE F OR REMOVING UNDESIRABLE FREQUENCIES FROM ELECTRIC CIRCUITS Filed July 3, 1935 'INVENTOR;

Patented Mar. 30, 1937 UNITED STATES DEVICE FOR REMOVING UNDESIRABLE FREQUENCIES FROM ELECTRIC CIR- CUITS Jisuke Miyazaki, Tokyo, Japan Application .r'uiya, 1935, Serial No. 29,758

2 Claims.

My invention relates to improvements in a device for removing the undesirable frequencies from a-communication line and has for its principal object to provide a device whereby the dis- 5 turbance caused by the voltage induced electromagnetically in the communication line may be removed in a simple and positive manner.

According to my invention, the voltage similar to that induced electro-magnetically in the communication line from the adjacent power line is produced and the voltage is amplified through an electric valve amplifier and stepped down by a transformer and is supplied to the communication line to be protected in an opposite'phase to that of the induced voltage.

For a more complete understanding of my invention referenceshould now be had to the drawing in which:

Fig. 1 is a diagram illustrating an embodiment of my invention and,

Fig. 2 illustrates another modification of my invention. e

In these figures, the same reference characters designate similar parts.

Referring more particularly to Fig. 1l9 designates a communication line to be protected. A protecting wire V2!) is stretched along the communication line I9. The wire 20 is grounded at more than two points. A voltage of the same wave form as that of the induced Voltage on the communication line will be induced on the wire 20 by the electromagnetic induction from the adjacent power lines. The protecting wire 20 includes a primary winding 5 of a transformer 4 and its secondary winding 6 isconnected to the grid of an amplifier valve 1. The plate circuit of the amplifier valve 1 includes the primary winding 9 of a transformer 8. The secondary windings Ill and ID of the transformer 8 are inserted in the respective line of the communication line IS in such a. manner that the induced voltage on the line H! may be opposed by the induced electro-motive force of the winding I0. I l designates the B-battery of the amplifier valve I.

The operation of the arrangement is as follows: As above mentioned, the wave form of the induced voltage on the wire 20 is the same as that of the induced voltage on the communication line IS. The voltage having the same wave 5 form as that of the induced voltage on the communication line is thus produced and is stepped up through the transformer 4 and magnified by means of the amplifier I. Since the magnified current passes through the primary-winding 9 of the transformer 8, its secondary winding ill or III will induce a voltage exactly similar in wave form to the induced voltage on the communication line IS. The secondary 'inducedvoltage may be adjusted to be the same in magnitude but opposite in phase with that of the induced voltage on the communication line [9 by suitably selecting the transformation ratio as well .as the polarity of the secondary windings l0 and ID with which the transformer 8 is connected to the communication line I 9. Being magnified through the amplifier I, the terminal voltage across the primary winding 9 of the transformer 8 will be very much increased comparing with the input voltage of the transformer 4. Accordingly, for obtaining a neutralizing voltage of the same magnitude as that induced on the line I9, the transformation ratio of the transformer 8 may be selected very large comparing with that of the transformer 4. The number of turns of the secondary winding Ill may thus be. selected to a small number as desired. The distortion of speech due to the reflection at the coil is not observed according to my invention.

Fig. 5 illustrates another modification of Fig. 4 in which'another communication line'2l running in parallel to the communication line i9 is used as the protecting wire of the latter. In this instance, the communication line-2| has drainage coils,at least, at two points and the input transformer 4 has two primary windings 5 and 5' which. are inserted in the respective line of the telephone circuit 2|.

In, all of these embodiments of my invention any of the coupling devices known to the art may be adopted in supplying grid potential to the amplifier valve. While I have shown a particular embodiment of my invention, it will be understood, of course, that I do not wish to be limited thereto since many modifications may be made, and I, there'- fore, contemplate-by the appended claims to cover any such modifications as fall within the true spirit and scope of my invention. 1

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

1. A device for removing the undesirable frequencies from a communication line, comprising a communication line, a protecting wire stretched along said communication line and grounded at least at two points to induce a voltage having the same wave form as that of induced voltage on the communication line due to the electro-magnetic induction from the adjacent power lines, an elec- 'tric valve amplifier, a coupling means for applying the induced voltage on said .protecting wire 2 I v i tothe grid of said valve, and a transformer for transforming said magnified induced voltage to be same in magnitude while opposite in phase' with that of the induced voltage on said communication line, the secondary winding of said transformer being inserted in said communication line. v

2. A device for removing the undesirable frequencies from a communication line, comprising electromagnetic induction from the adjacent power lines to said amplifier-valve, said communication circuit being grounded, at least, at

'two points through drainage coils, and an output transformer for transforming said induced voltage magnified through said amplifier valve to be same in magnitude while opposite in phase with .that of the induced voltage on the other communication circuit through the same'e1ectromagnetic induction, the secondary winding of said output transformer being inserted in'said other communication circuit.

JISUKE MIYAZAKI. I

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