US716203A - Wireless telegraphy. - Google Patents

Description

No. 7l6,203. I Patented D'ecflfi, I902;

' L. m: FOREST & E. H. SMYTHE.

T WIRELESS TELEGBAPHY. (Application filed Sept. 1, 1900.) (No ModeL).

m: "cams PETERS scum-um mm. WASHINGYON. n: c.

UNITED STATES PATENT J rFicE;

LEE DE FOREST, OF CHICAGO, AND EDWIN H. SMYTI-IE, OF FBEEPORT, ILLINOIS.

WIRELESS TELEGRAPHY.

SPECIFICATION forming part of Letters Patent No. 716,203, dated December 16, 1902.

Application filed September 1, 1900. Serial No. 28,722. (No model.)

To all rah/0111, it may concern:

Be it known that we, LEE DE FOREST, residing at Chicago, in the county of Cook, and ED- WIN H. SMYTHE, residing at Freeport, in the county of Stephenson, State of Illinois, citizens of the United States of America, have invented certain new and useful Improvements in Wireless Telegraphy, of which the following is a specification.

Our invention relates to improvements in wireless telegraphy, and particularly to an improved conductor of variable resistance adapted and intended for use in the circuit of the receiving apparatus of a wireless-telegraph system, the variation of the resistance of said conductor being caused by the passage of electric waves generated by a suitable transmitting apparatus.

The object of our invention is to provide a conductor which shall not only have the variation of resistance referred to, but which shall be so constructed as to be extremely sensitive, capable of operating at a practically unlimited speed, and practically permanent in its working capacity.

The invention may be embodied in various forms, all operating on substantially the same principle; but in the drawings accompanying a this specification and forming a part of this application we have shown a single simple apparatus including the variable-resistance conductor in one of the forms in which we have made and thoroughly tested it.

In the drawings referred to, Figure 1 is a diagrammatic representation of a receiving circuit in combination with the usual aerial conductor or receiver which is the initial element in the receiving apparatus, and Fig. 2

is a transverse section of the variable-resistance conductor shown partly in elevation and partly in vertical section in Fig. 1.

In the views, A is a local circuit, including a suitable battery or other source of electromotive forceB and a telephone-receiver or other signaling device 0, one link in the circuit being the variable-resistance conductor,

which will presently be described in detail.

D is the ordinary aerial conductor, having a height suitable to the conditions of its use, this conductor being in electrical connection with the local circuit A and also connected to ground or to suitable capacity by means of cuit. Choke-coils F F are interposed in the local circuit between the aerial conductor D and the signaling device on the one hand and between the aerial conductor and the battery or source of electric supply on the other hand, it being essential that the connection of the conductor E with the local circuit shall be between the corresponding choke-coil'F and the aerial conductor. The variable-resistance conductor is placed in the local circuit between the aerial conductor D and the groundwire E, and in the form shown in the drawings it includes two preferably metallic electrodes G G, which may be plane-faced bars overlapping each other, as shown, or may have such other form and relative position as will bring their opposed faces of suitable area into approximately parallel positions of slight separation. These electrodes may be held in their proper relation by any suitable means, and the space between them is filled by any suitable fluid, so held in place as to maintain a uniform tension.

In our experiments thus far we have found that liquids interposed between the electrodes give the most satisfactory results, for the reason that any liquid so interposed may be used for a considerable period of time without perceptible deterioration of its operative capacity, its maintenance in a stable or constant condition being thus assured without the use of anyapparatus for that purpose. Furthermore, we find that the liquid interposed between the electrodes is much more permanent in its operation than an interposed fiilm of vapor, which by reason of evaporation would require constant renewal. In the variableresistance conductor shown in the drawings the electrodes G G are supported by a suitable vessel H, containing a liquid in which the electrodes are immersed, the space between the overlappihg faces of the two electrodes being thereby filled with the liquid,

which, being interposed in series between the electrodes, forms the connection between the electrodes, and thus completes the conductor.

Under ordinary conditions when the receiving apparatus thus shown and described is not in operation the current generated by the local battery passes through the circuit including the signaling device, the chokecoils, and the variable-resistance conductor, no material resistance to the passage of the current being offered by the choke-coils or by the variable-resistance conductor, the resistance of which under such conditions is at its lowest limit. Upon the receipt of an electric impulse through the aerial conductor the resistance of the choke-coils to the passage of the wave forcesit to pass by Way of the ground connection E to the ground, and thus insures its passage through the variable-resistance conductor. The passage of the wave through the conductor greatlyincreases its resistance, and since the variable-resistance conductor is in the local circuit this change of resistance is indicated by the telephone or other signaling device, which is also in the local circuit. Our use of the variable-resistance conductor having the construction shown and described has been sufficient to demonstrate not only its extreme sensitiveness, but also its remarkable rapidity of action. The variation of resistance of the conductor due to -the passage of successive electric impulses is plainly marked, no matter how rapidly the impulses may succeed each other, and, in fact, the onlylimit to the distinct indication of the passage of successive impulses is the recording capacity of the signaling device or the capacity of the senses for distinguishing separate signals. This capacity for rapid repetition of the variation of resistance in the conductor is a consequence, as well as a demonstration, of the fact that the passage of the electrical impulse through the liquid interposed between the eloctrodes produces no change of conditions therein, except such as is instantaneously and automatically counteracted, the conductor being thus restored to its condition of normal resistance immediately after the passage of. each impulse. This rapidity of action of the variable-resistance conductor is of great practical importance, for the reason that it makes it possible to distinguish perfectly betweenimpulses generated with predetermined frequency at atransmitting station and other electrical impulses following each other at a different rate. This apparatus operates equally well, therefore,under varying electricalconditions, its action being perfect in the presence of atmospheric electric disturbances in the sense that the impulses from a transmitting-station have a uniform frequency of impulse,whereby they may be readily distinguished from other and accidental impulses. In fact the signaling device may be placed iuasuitablytuned circuit and may be. thus made to respond automatically to similarly-tuned impulses and to no others, the signaling device being thus made to automatically select impulses transmitted at a predetermined frequency.

In speaking of the interposed liquid as permanent orstable and as unchangedby the passage through it of electric impulses we have had in mind the evident fact that it is perfectly operative as a means of indicating the passage of a great number of successive impulses coveringa considerable period of time. We have nevertheless found it desirable to occasionally change or renew the liquid, and this may be accomplished by flowing a current of liquid through the vessel containing the electrodes or in any other simple and effective way. In the drawings hereinbefore referred to the electrodes are shown in a condition of immersion in the liquid, and this is one simple and evident way of securing the constantpresence of the interposed liquid between the electrodes. The best way, however, in which We have contemplated maintaining the constant pressure of the interposed liquid between the electrodes is to employ a suitable porous material constantly saturated with the liquid and to interpose such porous material between the electrodes. Our experiments have demonstrated that such arrangement results in the production of the best effects, and our theory is that the porous material operates to retain the particles of metal which are detached from one electrode by the-passage of the current and carried toward the other electrode and to prevent such metallic particles from becoming precipitated or from settling to the bottom of the vessel or receptacle containing the liquid in which the electrodes are immersed.

We have found in our experiments that in the use of an apparatus embodying the principles above set forth and wherein are employed metallic electrodes a deposit occurs on the negative electrode from the positive electrode, even where the electrodes are immersed in chemically-pure water, and therefore we are confirmed in our theory that the interposition of the porous body between the exposed or juxtaposited surfaces-of the electrodes forms a support or retainer for the metallic particles which would otherwise be transferred from one and deposited upon the other of the electrodes.

The liquid which we have used in our experiments and which we have found to be perfectly satisfactory in its operation is water; but we do not intend to limit our invention to the use of this particular liquid, as others equally desirable or even more desirable may be determined by further experiment. It will be understood, of course, that we do not limit the invention to the use of any simple liquid, since this term is evidently broad enough to include chemical solutions, dilute or otherwise, as well as liquids holding in suspension particles of any nature which may be found to contribute to the effective operation of the interposed film.

Then the electrodes are immersed in a liquid contained in an open vessel, as shown in the drawings,it is desirable that all those parts of the electrodes except the actually overlapping surfaces or juxtaposed portions be varconcerned.

lent results from the use of two electrodes,

any possibility of short-circuitingthrough the liquid. In referring to the overlapping or opposed surfaces of the electrodes we do not intend to impose any limitation so far as the extent of area of the opposed surfaces is In fact, we have obtained excelone having a plane surface of considerable area and the other having a thin or \l-shaped edge parallel to the plane surface of the first. This form is conveniently adjustable and has apparently exactly the same operation as the form including two overlapping plane-faced bars. We have only illustrated one simple form, for the reasonthat we do not desire or intend to make the shape orextent of the opposed surfaces of the electrodes an essential element of our invention.

We claim as new and desire to secure by Letters Patent- 1. In a receiver for electricaloscillations, the combination with a suitable receptacle adapted to receive a liquid, of electrodes supported in said receptacle and suitably separated from each other, the surfaces of said electrodes being covered with insulating material except at juxtaposited points, the liquid contained in saidreceptacle being interposed between said electrodes and forming a normally closed series electrical connection therebetween,as and for the purpose set forth.

2. Ina receiver for electrical oscillations, the combination with a receptacle adapted to receive a liquid, of suitably-separated electrodes supported in said receptacle in position to be immersed in the liquid contained therein, the surfaces of said electrodes being covered with insulating material except at juxtaposited points, whereby a body of liquid is constantly maintained in series relation between the exposed juxtaposited points or surfaces of said electrodes to complete electrical connection therebetween, as and for the purpose set forth.

3. In a receiver for electrical oscillations, the combination with two suitably-separated electrodes having opposed or juxtaposited conducting-surfaces, of a layer of porous material saturated with a suitable liquid, said porous material beinginterposed between and in series with the conducting exposed surfaces of said electrodes, andoperating to electrically connect said surfaces, as and for the purpose set forth.

4:. In a receiver for electrical oscillations,

. suitably-separated electrodes having juxtaposited exposed conducting-surfaces, a liquid body interposed between such surfaces,

and means for maintaining the metallic particles detached from the electrodes by the pas: sage of the current suspended in said liquid inthe space between the exposed surfaces of said electrodes, as and for the purpose set forth.

5. In a receiver for electrical oscillations,

the combination with suitably-separated electrodes adapted to receive a body of liquid between the exposed surfaces thereof, means for maintaining said body of liquid between said surfaces, and means for retaining the metallic particles held in suspension in said liquid between said surfaces, as and for the purpose set forth.

6. In a receiver for electrical oscillations, a local circuit, electrodes suitably separated from each other and arranged in said circuit, a receiving-conductor, a ground or capacity connection therefor, said electrodes being also included in said ground or capacity connection, said electrodes having a body of liquid interposed between the exposed surfaces thereof, and means for retaining the metallic particles detached from said electrodes from being precipitated, whereby electrical connection is maintained between said electrodes to normally close said local circuit, as

and for the purpose set forth.

7 In a receiver for electrical oscillations, a local circuit, electrodes suitably separated from each other and arranged in said circuit, a receiving-conductor, a ground or capacity connection therefor, said electrodes being also included in said ground or capacity connection, and a saturated porous body interposed in series between the exposed surfaces of said electrodes, as and for the purpose set forth.

8. In a receiver for electrical oscillations, the combination with suitably-separated electrodes having exposed juxtaposited surfaces, of means for maintaining metallic particles in suspension between such exposed juxtaposited surfaces, as and for the purpose set forth.

9. In a receiver for electrical oscillations,

a local circuit, electrodes suitably separated from each other and arranged in said circuit,

a receiving-conductor, a ground or capacity connection therefor, said electrodes being also included in said ground or capacity connection, and means for maintaining metallic particles in suspension between the exposed surfaces of said electrodes to normally close the circuit therebetween, as and for the purpose set forth. I

10. In a receiver for electrical oscillations, a local circuit, electrodes suitablyseparated from each other and arranged in said circuit, a receiving-conductor, a ground or capacity con nection therefor, said electrodes being also, included in said ground or capacity connection, and a porous body interposed in series.

between the exposed surfaces of said elec-. trodes, as and for the purpose set forth.

11. In a receiver for electrical oscillations,

a local circuit, electrodes suitably separated I from each other and arranged in said circuit,

a receiving-conductor, aground or capacity. connectiontherefor, said electrodes being also included in said ground or capacity connection, a receptacle adapted to receive aliquid,

said electrodes being immersed in said liquid, and a porous body interposed in series between said electrodes, as and for the purpose set forth.

12. In a receiver for electrical oscillations, a local circuit, a signal device, and a resistance device, included in said local circuit, said resistance device comprising suitablyseparated electrodes having an interposed body of liquid between the exposed surfaces thereof, means for maintaining or holding in suspension metallic particles in said liquid, in combination with a receiving-conductor, a ground or capacity connection for said conductor, said ground or capacity connection including said resistance device, and means for preventing the electrical oscillations in said receiving-conductor and its connection from traversing said local circuit, as and for the purpose set forth.

13. Ina receiver for electrical oscillations, a local circuit, a signal device arranged therein, a receptacle adapted to contain a liquid or fluid, electrodes arranged in said receptacle and suitably separated from each other, a porous body interposed in series between said electrodes to complete electrical connection between said electrodes, said electrodes being included in said local circuit, a receiving-conductor, a grounded or capacity connection therefor, said electrodes being also included in said grounded or capacity connection, as and for the purpose set forth.

14:. In a receiver for electrical oscillations, a local circuit, a signal device included therein, electrodes included in said circuit and suitably spaced apart, said electrodes adapted to receive a porous body saturated with a suitable fluid or liquid between the opposed surfaces thereof to complete electrical connection therebetween, a receiving-conductor, a grounded or capacity connection therefor, said electrodes being also included in said grounded or capacity connection, and induction devices arranged in said local circuit, as and for the purpose set forth.

15. In a receiver for electrical oscillations, the combination withsuitably-separated electrodes, a local circuit therefor, and means for confining the metallic particles in the space between said electrodes and comprising a fabric placed between said electrodes, as and for the purpose set forth.

In witness whereof we have hereunto set our hands, at Chicago, in the county of Cook and State of Illinois, this 29th day of August,

LEE DE FOREST.

EDWIN H. SMYTHE. Witnesses:

R. H. WILES,

OHAs. O. SHERVEY.

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