US2383420A - Thermionic valve circuits - Google Patents

Description

Aug. 21, 1945. Q G. J. s oLEs 2,383,420

- THERMI'ONI-C VALVE'CIRCUIT Filed Sept. 21, 1943 To V/'a'e0 Stage 7b Audio Stage Patented Aug. 21, 1945 ,l v 2333 4201 THERMI'ONIG VALVE CIRCUITS GrahamJohn SGOIeS EaSt sheentsLondon, En land, assigncr ,to ,Metropolitan vickers,Electri-r cal Company Limited, L ndo n,..En'gland,.a com:

pany of GreatBrltain Applicationvseptember 21, 1943;;Seria1;No;:503;280 lnyfireateBnit l iit ihrlflilsi 2 Claims; (CL

h oinvehtiontlt lateaetogthermionic.valvelcire r fication zarezzapplied,:whilstthe.cathode of this cuits,;and specificall stoysoecalledpdimitcrscircuitsau, diodeziszconnected-totthe earthyf busbar of the Thet ite rtionc'is znotablyi-but not exclusively, ape signahinput-v circuit; through two resistances -in pl-icable --in; circu-its wherein-z:,fromecomplexrorn, seriessdwhich. may be collectively bridged by a 5 t-tsmoothin'g. condenser) the junction of said two re 'de 'vedubYgmeansrof ta ,detectorzdevice s resistances beingi connectedto the-anode of the a The inyentiongisgapplicable;..in :the limiter:.-diode-and througha condenser to said v .-,.ca. lledr. ,panoramicii; radio-treceivers; busbanl-the'-cathode-of:the limiter diode being thetnature z f whic.hcwas-describedinfifElectrone" maintainednatran:appropriate positive potential ics Jun 940,and-,-wherein imbrief. a waveband,.alor bonveniently bybeing connected to the junction or dt rn be -an selectedcbnexof a t-pluralityznf, 2 point, oiatwo: further-resistances connected "bewaveba-nd slscanned fromuendtto ;;,end--by.,the, tween a source of positive potential and-said automat c;variationtp a tuning-parameter: busba'r. Of these resistances, the one connected a rate comparable with the frequency of ,theuperw between-the; cathodeiand busbar: of the limiter sistenceyofgyision; :the.- output;,or outputs due to l dio'de may be variable The-anodeofthe limiter any received radio transmissions which may be difideiisiconnectedwalsO.,to'-the .vide0 amplifier-or taking place within the waveband being indiother utilisation circuit. The output from the Gat s resonance P Components p pe detector diode may also be taken from a tapping dicular-to a time base waveband component on (which, may be variable) on that of the firstthe screen of a cathode ray tube, the time base mentioned two resistances which is connected p nent being provided sy r y Wit to the aforesaid busbar, and applied, for example, the scanning such as by means of a saw-tooth to an audio frequency amplifier.

yp of oscillation generator. Provision can be With the known arrangement just above demade whereby any Selecte o e of the thus i scribed, if the potential across the detector recated transmissions can be t ned in manually sistance between the limiter diode anode and and its modulation listened to or recorded or busbar becomes greater tha th t across th ot e w e indicated, that is to say, the Scanning resistance connected between the busbar. and the of the waveband can be effected ole y y hand cathode of the limiter diode, then the latter valve tsuch as through the turning o a knob about an conducts and prevents further increase of output,

, thereof, provides a detector arrangement whereby associated dial indicat the wavelength- In but for satisfactory operation this largely desuch a panoramic receiver it has been convenient pends upon the inherent poor regulation of t for the purpose of the rapid scanning of the diode detector circuit WaVebaIld t0 the Value of certain tuning The present invention comprises a thermionic components of the oscillator section of a fre- 5 valve circuit for detecting complex signals,

quency {hanger. valve in superheiemdyne wherefrom the different outputs are respectively with Whlch Superheterodyne clrcult preferably extracted by a detector arrangement adapted to has thrge of fliequency changing w limit at least one of said outputs to approxirespondlng intermed ate frequency circuits, and mately a predetermined value Without limiting preferably the Scanning 1S effected by reactor another output or outputs, the detector valve valve associated with the second oscillator being arranged as a per Se Well known cathode through an amplifier as described in copendlng follower or infinite impedance" type, and haw g z gfig$3 5}: gi jii f gg ffi g gw ing its cathode connected through a high resistance to the anode of a limiter diode, the cathode The present mventmn accordmg tonne aspect of which is positively biased. Said resistance one of the several outputs therefrom,such as'the must be high compared with the impedance of the diode. video output, is llmlted to approximately a predetermined value without, however, another outtype of detect r used 1n thepresent mven put or other outputs, such as an audio output, non fi o regulatmn so that Its Output V0115- being 1i it d age is largely-independent of the cathode load that good response is obtained A know llmlter arrangement (see Brltlsh and $0 armflged Specificatifn No. 474,356) comprises a diode rec- D t the hi h r quen es which it s desired tifier followed by a diode limiter such as for the t e clrcult shall eal w th. Smce the feed video output from the detector diode, to the resistance from the detector cathode to the l manode of which the signals, after suitable ampliiter diode anode is high compared with the 1mpedance of this valve, the output voltage from the limiter is limited to that of the cathode thereof, while the limiter circuit as a whole has no effect upon the output, such as audio output, which may be taken direct from the detector, in the known manner above described, and such is partly due to the relative impedances of the two circuits and partly due'to the inherent good regulation of the cathode follower circuit.

It will be appreciated that there may be provided more than one limiter circuit.

The single figure of the accompanying drawing is a circuit diagram illustrating the invention, and it will be seen that the detector valve VI is of the cathode follower type having its cathode connected to the earthy busbar B through the resistance R. in series with the potentiometer resistance RI across which latter is the condenser CI, whilst a condenser C2 is connectedacross both resistances, the radio frequency input to the valve VI being applied between the control grid A'and the busbar B. The cathode of the valve VI is connected through the high resistance R2 to the anode of the diode V2 and to the video stage such as indicated at Vid. A in Fig. l of the drawings of mycopending U. S. application Ser.

terminals and for limiting at least one of said outputs to approximately a predetermined value without limiting audio output, comprising a detector valve having a cathode and a signal receiving grid and arranged as a cathode follower, a limiter diode having an anode and a cathode, means including a resistance connecting the cathode of the detector valve to the anode of the limiter diode, said resistance being high relatively to the impedance of the limiter diode, and the cathode of the limiter diode being positively biased, means for taking the limited signal output from the anode of the limiter diode, a resistance in the cathode circuit of the detector valve, and means for taking another signal output from said last named resistance.

No. 503,278, filed of even date herewith, whilst 2. A thermionic valve circuit for detecting complex signals, comprising a detector valve having a radio frequency input grid connected to one terminal of the circuit and a cathode coupled by a resistance to the other terminal of the circuit, a limiter diode having an anode and a cath ode, means including a resistance connecting the junction of said series-connected resistances and the cathode of the limiter diode, and means for taking a signal output from said first-mentioned resistance.

GRAHAM JOHN SCOLES.

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