Патент USA US2115875код для вставки
May 3, 1938. 2,1 15,875 W, VAN B. ROBERTS REGENERATIVE DETECTOR‘ Filed Oct. 30, ‘1936 70 S/G/VA L w <4 6) V TOSIGA/AZ SOURCE 7 I / 2/ 20 ll _|,z1 $/24 5 ....../4 3/72] 1/ 7"“Z3 ?g 30 v \ FWAYAVAVAVL I , +8 9] \II 40 ‘* .L W9 Alf: AMPL. 11212 L ~1_5p / l ‘4/ “3/ V‘? ? ? INVENTOR WALTER VAN B. ROBERTS BY ATTORN EY Patented May 3, 1938 2,115,875 UNITED STATES PATENT OFFICE I 2,115,875 REGENERATIVE DETECTOR Walter van B. Roberts, Princeton, N. J ., assignor to Radio Corporation of America, a. corpora tion of Delaware Application October 30, 1936, Serial No. 108,426 2 Claims. My present invention relates to a regenerative detector, and more particularly to a new and improved type of regenerative detector circuit wherein audio ampli?cation is simultaneously .51 secured. In the prior art the regenerative detector is very well known, and it usually comprises a grid leak detector of the triode type wherein the plate circuit is regeneratively coupled to the tuned input circuit. It is known that such a regenera tive detector circuit suffers the disadvantage that a large radio frequency current ?ows in the plate circuit when strong signals are received. By virtue of the latter overloading occurs, since 1 Ql the plate circuit current variation that must be handled by the tube is equal to the sum of the audio frequency and radio frequency amplitudes. This operating disadvantage has discouraged the use of the regenerative detector circuit in situa 20 tions where it may well be employed. It is pointed out that the recent trend has been to (Cl. 250+27) to provide a regenerative detector circuit which is not only reliable in operation, but is economi cally manufactured and assembled in radio receivers. The novel features which I believe to be char acteristic of my invention are set forth in par ticularity in the appended claims; the invention itself, however, as to both its organization and method of operation will best be understood by reference to the following description taken in 10 connection with the drawing in which I have indicated diagrammatically several circuit or ganizations whereby my invention may be carried into e?ect. 15 In the drawing: Fig. 1 shows a regenerative detector circuit embodying one form of the invention, and Fig. 2 shows a detector circuit employing a_ modi?cation of the invention. Referring now to the accompanying drawing, 20 wherein like reference characters in the different ward use of a separate diode detector whose audio ?gures designate similar circuit elements, the frequency output is ?ltered free of radio fre quency components and impressed upon the grid 25 of a tube used solely for audio frequency ampli ?cation. numeral I denotes an electron discharge tube which may be of the well known 55 or 85 type. Accordingly. it may be stated that it is one of the main objects of my present invention to This type of tube essentially comprises electrodes 25 arranged to provide a diode section and an inde pendent ampli?er section. Brie?y, the tube com such regeneration being secured without appre prises a cathode 2, a diode anode 3 disposed adjacent a portion of the cathode 2 so as to receive electrons therefrom. The diode anode 3 and plate 5 are arranged to receive independent stream of electrons from the common cathode 2. Those skilled in the art will readily realize that when using a tube of the duo-diode triode type, the two diode anodes will be strapped together, 35 and thus furnish an effective single anode for ciably hastening the network overloading. the diode section. provide a regenerative detector network where 30 in the tube employed in the network comprises a diode section and an audio ampli?er section; the audio ampli?er section being utilized for radio frequency regeneration by regenerative feedback from the output of the audio section to the tuned 35 input circuit connected to the diode section, and Another important object of the invention may be stated to reside in the provision of a detector 4“ network which comprises a tube constructed to Furthermore, the ampli?er section of the tube may be of the screen grid, or pentode, type as in the 85 type tube, if desired. The signal input circuit 6 has its coil 1 mag 40 furnish a diode section and an ampli?er sec netically coupled to the source of signal current, tion, a signal input circuit being connected to the diode section to provide a diode detector by the latter functions as an audio ampli?er, and the condenser 8 tunes the input circuit 6 at the desired signal frequency. If the receiving system is of the superheterodyne type, then the source of signal energy coupled to input circuit 6 45 will be the output of the I. F. ampli?er. Since superheterodyne receivers are very well known to the plate circuit of the ampli?er being relatively those skilled in the art it is not believed neces tightly coupled to the detector input circuit, and sary to describe such a system in detail, except 50 to point out that the input circuit 6 would be tuned to the operating I. F., and the condenser 8 would be of ?xed value. If the receiving system is of the tuned radio frequency type, then one, or more, tunable radio frequency ampli?ers pre cede the input circuit 6, and the variable con denser 8 would have its rotors arranged for uni control adjustment with the rotors of the variable condensers used in the preceding ampli?ers. The diode load resistor 9 is connected between 60 circuit, the audio frequency component of the 45 detected signal current being impressed upon the control grid of the ampli?er section where 50 a relatively loose coupling being provided be tween the ampli?er grid and the diode detector input circuit whereby the ampli?er functions to provide regeneration of the signal current with out carrying sufficient radio current to appre 551 ciably hasten overloading of the ampli?er output circuit. Still other objects of the invention are to im prove generally the e?iciency and utility of re 60 generative detector circuits, and more especially . 2 2,115,875 the low alternating potential side of input circuit 5 and the grounded cathode, the by-pass con denser lll being shunted across resistor 9. The audio frequency component of detected signal current is impressed upon the control grid 4 by connecting the latter to an adjustable tap II. The tap H is slidable along load resistor 9, and' is connected to control grid 4 through a path which includes condenser l2 and the coil 13. The 10 latter is reactively coupled. to input coil 7, and the arrow through coils ‘I and I3 denotes ad justability of the reactive coupling between the two coils. The junction of coil I3 and condenser l 2 is connected to ground through resistor l4, and 15 the function of this resistor is to provide a de? nite direct current operating potential for grid 4. The plate 5 of tube I is connected to the posi tive terminal of a source of direct current po tential, which source is not shown, through apath which includes the feedback coil l5 and the head phones IG. Coil l5 and coil '1 are reactively cou pled. If desired, the headphones l6 may be re placed by any other type of reproducer, such as a loudspeaker, and the audio output of the plate 25 circuit of tube I may be ampli?ed in one, or more stages of audio ampli?cation. In the circuit shown in Fig. 1, a relatively strong feedback coupling is provided between the plate circuit of tube I and the tuned input circuit 30 6. A variable coupling of the correct phase for regeneration is then provided between input cir cuit 6 and control grid 4. Since the feedback coupling is much tighter than customary in re generative circuits heretofore used, it is only 35 necessary to impress a small fraction of the radio frequency voltage across coil 1 upon the grid 4 to obtain su?icient regeneration, or even oscilla tion. Since the radio frequency voltage im pressed upon grid 4 is very small there will be 40 only a very small radio frequency current in the radio frequency choke coil 30 to the control grid 4. The grid leak resistor 3| is connected in se ries between the control grid 4 and the usual grid bias resistor 40. It will be understood that the voltage drop across resistor 40, the latter being shunted by the by-pass condenser 4|, provides the normal grid bias for control grid 4. The anode side of load resistor 9 is connected to the midpoint of input coil 1, and an automatic volume control connection (AVC) is shown connected to 10 the anode side of resistor 9. The resistor-con denser network 50 ?lters the radio frequency components from the AVG’ bias, and, as is well known, the latter bias is applied to one, or more, radio frequency ampli?ers for reducing the gain 15 of the ampli?ers as the signal amplitude in creases thereby to maintain the‘ carrier ampli tude at the input circuit 6 substantially uniform over a relatively wide range of signal variation at the signal collector of the receiving system. While I have indicated and described several systems for carrying my invention into effect, it will be apparent to one skilled in the art that my invention is by no means limited to the particular organizations shown and described, but that many modi?cations may be made without de parting from the scope of my invention, as set forth in the appended claims. What I claim is: 1. In combination, in a detector network, an 80 electron discharge tube provided with a diode section and an ampli?er section, a tuned signal input circuit connected to the diode section and including means for rendering the diode capable of detecting signals, means for impressing the audio component of detected signals upon the control grid of the ampli?er section, an audio utilization means in the plate circuit of the am pli?er section, means tightly coupling the plate circuit of the ampli?er section with the detector plate circuit, and accordingly this will not bring input circuit to provide strong regenerative feed about overloading appreciably sooner than if re generation were not used at all. For purposes of back thereto, and a reactive coupling between the control grid of the ampli?er section and said de illustration, it is pointed outthat the coupling tector input circuit whereby the ampli?er section 45 between coils l5 and 1 may be one such as would functions to regenerate signal currents, said re 45 ordinarily be employed for ampli?cation purposes where a plate circuit, or primary coil, is coupled to a tuned secondary circuit. The voltage step tight coupling and to an extent such that only a very small radio frequency current flows in said down between coils l and l3 is variable over a plate circuit. 50 range‘including a step down that just compen sates for the ampli?cation action, which particu lar step down is the critical value for sustained oscillations. In Fig. 2 there is shown an alternative circuit 55 arrangement employing the same method of op eration, but having its regeneration controlled by a variable capacity instead of a variable mutual inductance. In this ?gure any radio frequency component in the plate circuit is forced by choke 60 coil 20 to flow through condenser 2| back into the tuned input circuit 6. The control grid 4 is connected to a point 22 which is at zero radio frequency potential when the adjustable con denser 23 is suitably adjusted. .The tuning con 65 denser 8 is connected in shunt to the adjustable condenser 23 and the ?xed condenser 24, both of the latter condensers being connected in series. A slight variation of condenser 23 will impress a small radio frequency potential upon the control 70 grid 4 and produce regeneration. The diode detector has its audio frequency out put connected through the condenser l2 and active coupling being substantially less than said 2. In combination, in a detector network, an electron discharge tube provided with a diode section and an ampli?er section, a tuned signal input circuit connected to the diode section and including means for rendering the diode capable of detecting signals, means for impressing the audio component of detected signals upon the control grid of the ampli?er section, an audio utilization means in the plate circuit of the am pli?er section, means tightly coupling the plate circuit of the ampli?er section with the detector input circuit to provide strong regenerative feed back, a reactive coupling between the control grid of the ampli?er section and said detector input circuit whereby the ampli?er section functions to regenerate signal currents, and said coupling between the plate circuit of the ampli?er section and the detector tuned input circuit being rela tively stronger than said other coupling to the ampli?er control grid, the said reactive coupling being sufficiently small to prevent overloading of the said plate circuit by radio frequency currents. WALTER VAN B. ROBERTS.