US1645301A - Magnetic amplifier and self-modulator - Google Patents

Description

Oct. 11, 1927. 1,645,301

J. SLEPIAN MAGNETIC AMPLIFIER AND SELF MODULATOR Filed April 21, 1921 WITNESSES: INVENTOR Jose 0f? Slep/an.

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ATTORNEY Patented 041.11, 1927.

' UNITED STATES PATENT o-Fnca.

JOSEPH SLEPIAN, OF WILKINSBUBG, PENNSYLVANIA, ASSIGHOB TO WIBTDIGEOUII ELECTRIC & MANUFACTUBIHG COMPANY, A CORPORATION OF PENNSYLVANIA.

MAGNETIC MIDI FEB AND SELF-KODULATOB,

Application med April :1, 1921. 8er1a1Ko..488,208.

My invention relates to wireless systems and more especiall to electrical systems which may be emp oyed either to amplify or to modulate the variable currents employed in wireless telegraph or telephone systems.

One object of my invention is to rovide an amplifying system which is not imited to the amplification of relatively small amounts of power b reason of inherent limitations in the design thereof.

Another object of my invention is to provide simple and eflicient means whereby the undamped oscillations in sustained current-- transmitting systems ma be periodically modulated to admit of t eir rece tion by receiving stations which are unab e to receive undamped signals.

Other ob'ects will be apparent from the following description, taken in connection with the accompanying drawings.

Heretofore, in systems of amplification, it has been possible to amplify only relatively small amounts of power by reason of structural and theoretical limitations in the amplifying devices employed.

Furthermore, in the art of signaling, it has been customary, in stations employing sustained oscillating currents, to communicate with receivin stations unable to receive the undampe signals radiated therefrom by employing a special spark transmitter.

According to my invention, I provide an electrical system which may be employed, with slight modifications in the design thereof, either as an amplifier system for amplifying large amounts of power or as a selfmodulating) system for producing audiblefrequency eats or groups of radiated waves in contmuous-wave, wireless-transmission systems.

In my coending application, Serial No. 463,209, file April 21, 1921, I have shown a purely electromagnetic system for accomplishing the desired result-s. In the application just mentioned, the system comprises a circuit having radio-frequency currents therein and a magnetizing winding, a circuit having audio-frequency currents therein and a magnetizing winding, a common.

magnetizable core member associated with said magnetizing windin s, reactance devices resonant to said ra io-frequency our- 5 rents included in said first-named circuit for causing the modulations of the radiofrequency currents tolag the modulating audio-frequency'currents.

In the system 'ust described, it was found that, if the osses in the audio-flew quency circuit were sufficiently small, the effect of the lag between the modulations of the radio-frequency circuit and the modulatmg audio-frequency circuit is to cause a transfer of energy from the radio-frequency circuit to the audio-frequency circuit tending to maintain the currents in the'latter circuit without additional audio-input. Thus, the system may easily become selfmodulating. I

It was further found that if the system were soadjusted that it was on the point of sustaining the currents in the audiofrequency circuit, small changes inthe value of the audio-input 'efi'ect relatively large changes in the value of the radio-frequency currents.

I have found, however, that the desired results heretofore mentioned may also be obtained by emplo inga mechanical movable armature mem er which is disposed between two small electromagnets; one of which is excited by the audio-frequency currents and the other of which is excited by the radio-frequency currents.

My invention may best be understood by reference to the accompanying drawings, in which:

Fig. 1 is a diagrammatic view of circuits and apparatus embodying my invention.

' Figs. 2, 3 and 4 are curve diagrams illustrating the fact that, with the radio-frequency circuit in a nonresonant state, substantially no mechanical work is done by the force upon the armature due to the radio-frequency currents.

Fig. 5 1s a curve diagram illustrating the fact that, with the radio-frequency circuit resonant to the radio-frequency currents therein, the currents'just mentioned will do mechanical work upon the armature tending to sustain its motion.

Referring to Fig. 1, a radio-frequency circuit 1 is 'operatively connected to a local source of radio-frequency currents 2 through coupling coils 3 and 4, and to an audio-frequency circuit 5 through a magnetic device 6.

The source of energy 2 is shown comprising an are 7, which is shunted by the coup coil 4 and a condenser 8. It is understoo however, that m invention 7 is not to be limited to the particular t pe of oscillation generator shown in the rawings, as other sources of radio-frequency or ultraaudio-frequcncy currents may be employed.

The u magnetiza le members 12 and 13 carrying .windin 9 and 11 respectively, which are include ,res ctivel ,in the ra 'o-frequency circuit 1 an in the audio-frequency circuit 5. Flexibly mounted between the magnetiz'able members 12 and 13 is an armature member 14 which may be secured to a supporting member 15 by means of'a flexible memberor spring 16, and is so disposed between the magnetizable members 12 and 13' that it ma periodically vary the self-inductance 0! the coil 9.. The natural period of the s ring 16, with the armature 14 attached t ereto, is preferably resonant to the frequency of the audio-frequency currents in circuit 1.

The audio-frequency circuit 5 may comprise one or more of the following elements: a source of audio-frequency, such as a detector device for incoming signals (not shown); a coupling coil 17, which is associated with a pair of feed- backcoils 18 and 19 hereinafter mentioned; and an inductance coil 21 and a condenser 22 for tuning the circuit to the audio-frequency currents.

The radio-frequency circuit 1 is shown as comprising the coupling coil 3, the winding 9,-an inductance coil 23 and a condenser 24 for tuning the circuit to resonance with the source of energy 2; and a pair of rectifier circuits 25 and 26 which are connected in shunt to each other and in series relation in the circuit 1. The rectifier circuits 25 and 26 include, respectively, indicating devices 29 and 31 shown as a air of telephone receivers and the opposite y connected rectifiers 27 and 28. The indicating devices 29 and 31 may be shunted also by the feed- back coils 18 and 19, which are connected in opposition, as shown.

The magnetizable members 12 and 13 are preferably operated upon the linear portion of the magnetization curve. 7

The curve diagrams shown in Figs. 2, 3 and 4 explain the fact that, if the radio-frequency circuit 1 were non-resonant to the source of energy 2, the modulation of the currents therein by the audio-frequency currents would be eifected with just sufficient power input in the audio-frequency circuit to supply the energy losses in the magnetic device 6. 7

Fig. 2 is a. curve diagram showing the variations in the air-gap length of the magnetizable member 14, with respect to the magnetizable member 12; and, for purposes of illustration, has beenrepresented in the sine-wave form.

etic device 6 inc des a pair of- Fig. 3 is curve diagram showing the modulations of the radio-frequency currents produced by the audible-frequency variations in the reluctance of the magnetic path through the armature member 14 and the magnetizable member 12. In the last-mentioned diagram, curve 32 represents the radio-freqiiliency oscillations, and curve 33 represents t e audio-frequency modulation thereof. Neglecting the slight lag, equalto a small fraction of the radio-frequency period, which would be caused by hysteresis, it is evident that the mean pull upon the armature 14, that is caused by the radio-frequency currents is in phase with the modulations 33 and it has been so illustrated in Fig. 4.

l rom the foregoing curve diagrams, it may readily-be seen that the curve representing the mean pull upon armature 14 is in phase with the curve representing the variations in the air-gap length, and, therefore, in gadrature with the velocity of the armature.

ence, no mechanical work is done by the radio-frequency currents upon the magnetic device 6 under the conditions assumed. The audio-input, therefore, is required to supply only the losses in the magnetic device 6, in order to modulate the radio-frequency currents. v

I have found that, by adding a seriesresonant device, such as that indicated at 23,24, tuned to resonance with the radio-frequency currents, the modulations of the radio-frequency currents are caused to lag behind the modulating audio-frequency currents, as indicated in the curve diagram shown in Fig. 5.

The reason for the lag produced by the addition of the series-resonant reactance device will probably be best understood by av consideration of the energy-stored by the device. If an oscillatory electromotive force of constant amplitude is suddenly impressed upon an oscillatorycircuit containing a series-resonant device, the currents will not immediately reach a steady value, since the energy stored in the resonant device must be supplied from the source; but the amplitude of the oscillations will gradually increase for a number of cycles, dependent upon the ratio of the stored energy to the resistance load, as is well known. Similarly if the oscillatory electromotive force is decreased in amplitude, or withdrawn altogether, the excess energy stored in the reactance devices will cause the corresponding modulation of the currents to be postponed to a time which may be a number of cycles later.

The result of such lag in the present device is that the modulations have a component in phase with the movements of the armature. as well as a component displaced 90 thereupon. It will be seen that the firstmentioned component tends to maintain the movements of the armature, and that energy is thus supfilied to .the audio-frequency circuit from t in%to reduce the aha-z: ry audio input.

- y sufiiciently reducing the in the audio-frequency circuit, enough power, may be supplied thereto from the radio-frequency circuit to maintain the currents therein without additional audio-frequency input. The system then becomesa self-modulator.

I have found that my system is most efiicient as an amplifier. upon the adjustment of the inductance coil 23 and the condenser 24 to such value that the system is on the oint of sustaining currents in circuit 5. dditional amplification may be obtained through the feed- back coils 18 and 19 and the coupling coil 17, said coils feeding back the audio-ire uency modulation of currents in the ra io-freauency circuit 1.

Assuming ra io-frequency currents su plied to the radio-frequency circuit 1 y means of the source of radio-frequency energy 2, the effect of impressing currents of an audible frequency upon circuit 5 is to effect the modulatlon of the radio-frequency currents in circuit 1 at frequencies corresponding to those in the audio-fr uency clrcuit 5, all as hereinbefore describe The effect of the rectifiers 27 and 28 is to render audible, in the indicating devices 29 and 31 the note corresponding to that of the audiorequenc modulations.

The self-mo ulating characteristic of my system is of particular importance in marine work in that iteliminates the spark transmitters which have heretofore been considered necessary in continuous-wave systems when desiring to communicate with receiving systems responsive only to energy radiated by s ark transmitters.

Another a vanta e of my invention resides in the fact t at it embodies means whereby reception of signal impulses may be efiected from continuous wave systems without heterodyning the received energy.

Still another advantage of my invention resides in the provision of a magnetic amplifying system wherein relatively small or large amounts of power may be efficiently am lified.

ile I have shown only one embodiment of my invention, in which the inductance of a circuit is mechanically varied, it is obvious that a mechanically varied condenser may be equally as well employed without departing from the s irit and scope of my invention. I desire, t erefore, that only such limitations shall be imposed thereon as are set forth in the appended claims.

I claim as my invention:

1. In a magnetic amplifier, a circuit having radio-frequency currents therein and a magnetizi winding, 8. second circuit having audiorequency a magnetizing winding, a magnetlzable meme radio-frequency circuit, tendcurrents therein and her so dis d "that the resultant motion thereo causes cha es in the inductance of the radio-frequency circuits, whereb the radio-frequency currents may be mod ated at frequencies corresponding to the audiofrequency currents. Y

2. In a ma etic amplifier, a circuit-havmg sustain oscillating. currents therein and a magnetlzing winding, a circuit having aud o-frequency currents therein and a magnetizin wlnding, a ma etizable member adap to respond to t e magnetic fields set up by currents in said magnetizin windings, w ereby the currents in 'sai firstnamed circult may be modulated at frequencles corresponding to those in said second-named circuit.

3. In a ma netic amplifier, a circuit havmg sustaine oscillatin currents therein and a magnetizing win ing, a second circuit having audio-frequency currents therein and a magnetizing winding, magnetizable members for each magnetizing winding, and a vibratory magnetizable member disposed adjacent said first and second-named magnetizable members. 4. In a ma netic amplifier, a circuit having sustaine oscillating currents therein and a magnetizing winding, a second circuit having audio-frequency currents therein and a magnetizing winding, magnetizable members for each magnetizing winding, an armature responslve to the magnetic fields set up by currents in said first and second-named magnetizing windings, whereby said oscillating currents are modulated in accordance with said audio-frequency currents and means for causing the modulations of said oscillating currents to have such phase relation to said audio-frequency currents that the mean pull of said modulated currents on said armature has a component in phase with the movement thereof.

5. In a magnetic amplifier, a resonant circuit having radio-frequency currents therein and a magnetizing windin a circuit having audio-frequency currents t erein and a magnetizing winding, magnetizable members for each magnetizin wlnding and a flexibly mounted magnetlzable member responsive to the magnetic fields set up by currents in said In etizable members, the resultant motion 0 said flexibly mounted magnetizable member being such that the .movement thereof is approximately in phase with the force thereon caused by said radio-frequency currents.

6. In a magnetic amplifier, a circuit carryin audio-frequency currents therein Y and inc udin a magnetizing winding and a coupling coi a circuit carrying radio-frequency currents therein and includin a magnetizing winding, a pair of recti ers connected in parallel opposition, an indicating device and feed-back coils associated J an with said coupling coil, magnetizable members associated with each ma etizing winding, and a flexibly mounte magnetizable member so disposed adjacent said magnetizing windings that the resultant motion thereof effects the modulation of said radio frequency currents at a frequency corresponding to the audio-frequency currents.

7. The combination with a source of sustained oscillations, of a magnetizing coil connected thereto, a vibratory armature associated with said coil, whereby the reactance of the latter is varied in accordance with the movements of said armature, said armature I cuit having sustained oscillating currentstherein, a second circuit having audio-frequency currents therein, means controlled by said audio-frequency currents for mechanically varying the reactance of said firstnamed circuit to cause corresponding modulations of the currents therein, and auxiliary means for transferring audio-frequency power from said first-named circuit to said second-named circuit.

10. A magnetic amplifier comprising a circuit having sustained oscillating currents therein, a second circuit having audio-frequency currents therein, means controlled by said audio-frequency currents for mechanically varying the reactance of said first named circuit to cause correspond' modulations of the currents therein, a rectifier for said oscillating currents, and means for transferring audio-frequency power from said rectifier currents to said audio-frequency circuit.

11. The method of varying the reactance of a sustained oscillatory-current circuit b means of a tuned vibratory member, whic consists in so varying the phase relati0n shi between the variations in said reactance an the resultant modulations in said oscillatory current that said modulations have a component in phase with the velocity of said vibratory member. I

12. In a carrier-current signaling system, the combination with a carrier-current circuit thereof, of modulating means comprising an inductance device included in said circuit, a second circuit having audio-frequency currents therein, and movable means controlled by said audio-frequency currents for mechanically varying the reactance of said inductance device to cause corresponding modulations of the currents in said firstnamed circuit 13. In a carrier-current signalingsystem, the combination with a carrier-current circuit thereof, of modulating means comprising a magnetizable-core inductance device included in said circuit, a movable magnetizable armature included in the magnetic circuit of said inductance device, and means for moving said armature in such manner as to vary the inductance of said device in response to a signal or signals to be transmitted.

In testimony whereof, I have hereunto subscribed my name this 14th day of April, 1921.

JOSEPH SLEPIAN.

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