US2336855A - Electron discharge oscillation generator - Google Patents

Description

Dec. 14, 1943. G. w. FYLER- 2,336,355

ELECTRON DISCHARGE OSCILLATION GENERATOR 7 Filed D80. 7, 1942 Fig. I.

Inventor" 1 George W. F'gler b WW6: JMZ

3 His Attorney.

Patented Dec. 14, 1943 ELECTRON DISCHARGE OSCILLATION GENERATOR George W. Fyler, Stratford, Conn., assignor to General Electric Comp York any, a corporation of New Application December 7, 1942, Serial No. 468,040

Claims. (01. l79100.4j

My invention relates to electron discharge oscillation generators and it has for one of its objects to provide such an oscillationgenerator the operation of which is due entirely to the initial velocity and contact potential of electrons emitted from the cathode of the electron discharge device employed. Thus the use of externally applied anode operating potential is obviated.

In accord with my invention an electron dischargedevice is employed having a cathode all of the electron emitting surface of which is at the same potential; This cathode may be heated in any desired way but I have found that electron discharge-devices such as are commonly employed in radio .receivers having cathodes heated electrically by heating elements enclosed within the cathode are satisfactory. It is an object of my invention to produce oscillations by such a discharge device without application thereto of externally applied operating potential.

Another object of my invention is to provide means for modulating oscillations so produced in accord with voice or music.

A further object of my invention is to augment the output of such an oscillation generator utilizing the contact potential between the anode and cathode of a second discharge device.

The novel features which I believe to be characteristic of my invention are set forth with particularity'in the appended claims. My invention itself, however, both as to its organization and method of operation, together with further ob-, jects and advantages thereoflmay best be understood by reference to the following description taken in connection with the accompanying drawing in which Fig. 1 represents an embodiment of my invention, and Fig. 2 represents a modification thereof.

Referring to Fig. 1 of the drawing, I have shown at I an electron discharge device having an indirectly heated or unipotential cathode 2,,

a control electrode 3 and an anode 4. This discharge device may be of many different types but I have found that discharge devices such as are commonly employed in radio receivers operate satisfactorily in my invention. Such discharge devices, for example, may be of the 'ltype known -as the 6J5, GFB-G, 6C5, 6K7 connected as a triode and devices of similar character. Between the anode 4 and the control electrode 3 an oscillatory circuit 5 is connected through condenser 6 and .the usual grid leak and condenser combination I,

8. The oscillatory circuit 5 comprises the usual the unipotential cathode 2.

variable tuning condenser 9 and tuning inductance l0 connected in parallel, an intermediate point on the inductance 10 being connected to This cathode is heated by means of a heating element which may be enclosed within the cathode; that is, the cathode may be a cylinder, as is usual in such discharge devices, and the heater comprises a resistance element H mounted within the cylinder and heated by electrical current flowing therein. This current may be supplied from a suitable source connected to the lines I2 and in the particular form of the invention shown in Fig. 1 is supplied to the heating element ii through aportion of the winding of a phonograph motor I3. This motor thus acts as a transformer to slip down the voltage between lines E2 to a value suitable It has been found that a discharge device so I connected .is eifective to excite oscillations in the circuit 5 of considerable intensity even though there be no electromotive force applied externally of the discharge device. The entire operation of the device is apparently due solely to the initial velocity of electrons emitted from the surface of the cathode 2 all parts of which are at the same potential. These electrons which are emitted from the cathode by reason of the heat applied thereto penetrate the space surrounding the cathode and some of them fall into the cold electrodes 3 and 4 producing current in the circuit between such cold electrodes and the oathode. This, of course, is the Edison effect which has been well known to those familiar with discharge devices since the discovery thereof by Thomas A. Edison. It has been found, however, that when the circuits extending from the cathode to these respective cold electrodes are properly coupled, as by the oscillatory circuit 5, this Edison effect is sufficient to excite oscillations of output intensity in this oscillatory circuit. It has been found that quite satisfactory transmission of music reproduced from a phonograph and modulated onto the carrier wave so generated by circuits such as illustrated in Fig. 1 may be had, such oscillations being of sufficient intensity to be intercepted by an ordinary broadcast receiver plied to the oscillator circuit.

situated nearby, as within a range, for example,

of 50 feet. Such operation renders the system the condenser 9 for operation at some frequencyto which the receiver is tunable. This may be a frequency in the broadcast band, which extends from 550.kilocycles to 1720 kilocycles, or it may be tuned to a frequencyin one of the short wave bands. The household receiver may thenbe tuned to the same frequency to receive the oscillations generated by the oscillator I and radiated by the antenna I9."

It has also been found that with the system as thus described the oscillations generated may be modulated by the potential generated in the piezoelectric "crystal by as much as 60% f the carrier wave without encountering objectionable distortion. Thus the system operates quite satisfactorily without the application of any external potential, although of course, during the operation of the phonograph the potential generated by the piezoelectric crystal is present in the circuit. The operation of theoscillator, however,

is not dependent thereon but is only modulated by this potential which is generated by the crys- .tal. Only a small portion of thi potential, however, is necessary to'the required modulation. Accordingly, the variable contact 20 may be uperated well to theleft, as shown'in the drawing on-the resistance. I5, to reduce the potential ap- In Fig. I, an antenna wire I9 is shown connected to one terminalof the oscillatory circuit 9, I0 to increase the radiation of the generated 3 oscillations. Of course, any of the usual means for the radiation of such oscillations may be employed; and I particularly contemplate the alternativ''designof coil III as a loop radiator. The

sturns of such loop radiators have large area and such coils also have high ratio of inductance .to

ode) is in aiding relation with that between the cathode and anode of v device I. Thus the anode circuit of device I extends from the anode thereof through a portion of resistance I'I, cathodeto anode space of discharge device Z I, and a portion of inductance I 0 back to the cathode'of device I. This arrangement operates to augment the production of oscillations while still avoiding the use of any source of operating potential external of'the discharge devices themselves. The discharge device I8 may be of the same type as the device I and, if preferred, these devices may be arranged within the same envelope. As shown in the drawing, the heaters for the cathodes ofthe two devices are connected directly in parallel and to the phonograph-motor I 3.

It has been found from actual test that oscillations of suflicient intensity for practical modulation by means of a phonograph pickup and reception over short distance in a radio receiver may be had by use of discharge devices of any of the types above mentioned in the oscillator circuit. or course, the anode current in such devices must be suiiicientl great to supply the losses in the grid circuit and in theoscillatory circuit, and it is therefore preferred that the discharge device he one having as small an initial grid current as possible as compared to the plate current.

While very satisfactory operation may be had by the use of discharge devices of the types mentioned above, certain considerations suggest that even better operation may be had by the use of devices of higher Gm., i. e. devices in which the anode current change per unit of change of grid voltage is greater. In devices of the types which I have employed, the value of Gm. is about 2000 with normal rated anode voltage. I believe devices of still higher Gm, are to be preferred and that close spacing of both the anode and control electrode to the cathode is desirable. Such spacing results in larger current in boththe anode and control electrode and while it may increase losses inethe circuit between the control electrode and cathode, yet greater output will result.

that I do not Wish to be limited thereto since many modifications both in the circuit arrangement and in the instrumentalities employed may be made, and I contemplate by the appended claims to cover anysuch modifications as' fall within the true spirit and scope of my invention. What I claim as new and desire to secure by Letters Patent of the United States is: 1. The combination, in an electron discharg oscillation generator, of an electron discharge device having a-heated unipotential cathode and two cold electrodes, an oscillatory circuit, a circut from one of said cold electrodes to said cathode including said oscillatory circuit, a circuit between said otherelectrode and cathode, the

duced by electrons emitted from said heated unipotential cathode and impinging on said one cold electrode being sufiicient to produce sustained oscillations in said oscillatory circuit.

2. The combination, in an oscillation generator, of an electron discharge device having aheated unipotential cathode and two cold electrodes, circuits from each of said cold electrodes, respector, of an electron discharge device having a heated unipotential cathode and two cold electrodes, and an oscillatory circuit connected between said two cold electrodes and having an intermediate point connected to said unipotential cathode, the connection from said cathode to said intermediate point and through said oscillatory circuit to said cold electrodes being conductive to unidirectional current produced therein by reason of contact potential between said cathode and control electrodes, and said oscillatory circuit having oscillations excited therein solely by reason of the action of said discharge device with respect to said currents.

While I have shown particular embodiments of my. invention, it will of course be understood 4. The combination, in an oscillation generator, of an electron discharge device having an anode, a heated unipotential cathode and a control electrode, a circuit between said anode and cathode and between said'control electrode and cathode. a coupling between said circuits to support oscillations produced therein solely by reason of current flowing therein due to the initial velocity of electrons emitted by said unipotential cathode, and a piezoelectric phonograph pickup 10 device coupled to one of said circuits to modulate said oscillations, the sole potential supplied to said circuits external of said discharge device being that supplied by aidpiwoelectric pickup.

5. The combination, in an oscillation generator, 5

01' an electron discharge device having an anode, a heated unipotential cathode and a control electrode, a second discharge device having an anode and a heated cathode, a circuit between said first anode and cathode including the space between said second anode and cathode in aiding sense with respect to contact potentials between said cathodes and the respective anodes, a circuit between said control electrode and cathode, and a coupling between said circuits to support oscillations excited therein by action of said first device with respect to current produced solely by said contact potential in said two devices.

GEORGE W. FYLER.

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