Патент USA US2129726код для вставки
Sept. 13, 1938. - A, w_ BARBER 2,129,726 - . RECTIFIER CIRCUITS Filed Jan. '50, 1956 I ' i-i. SOURCE OF 0. F9 -~—-||-H - M - @ ‘ /@ I2 SOURCE OF °_ INPUT S'GNAI- OUTPUT ‘ ,C o. <73 DEVICE -/5 I b ¢!\ + . ° d Wmuwmm- H93 e ii ' ' A Fly 4 + 4, Fig.5 , . INVENTOR WMBa/Léw v, Patented Sept. 13, 1938 2,129,726 UNITED, STATES PATENT OFFlCE 2,129,726 RECTIFIER CIRCUITS Alfred W. Barber, Flushing, N. Y. . Application January 30, 1936, Serial No. 61,457 (c1. 250-27) 13 Claims. This present invention of mine concerns im Fig. 1 shows a circuit embodying my present provements in electrical circuits. It particularly invention- relates to methods of, and means for recti?ca tion in radio receivers and the like. *5 ‘ One object of my‘invention is to produce a recti?er circuit in which direct current products vare cancelled out in the output. Another object is to produce a recti?er in which the radio fre quency drop across the recti?cation load circuits l0 balance yielding an output voltage free from . Fig. 2 shows another form of my invention. Fig. 3 shows a curve representing a modulated radio frequency'wave. 5 Fig. 4 shows curves useful ,in explaining the operation of the circuit of Fig. 1. Fig. 5 shows curves useful in explaining the operation of the circuit of Fig. 2. In Fig. 1 I have shown a circuit embodying 10 'my present invention. A coil I receives a voltage from the “source of input signal” which may radio frequency components. A third object is to produce a recti?er circuit in which the useful demodulated alternating currents produced in the output circuit, from a modulated radio fre quency wave applied to the input, is the differ ence between the products developed across two be'a radio receiver up to the second detector or it may be any other carrier wave amplifying or coupling device. Coil I is magnetically coupled 15 to coil 2 although other types of coupling may different load circuits. be used, as for instance capacity coupling. One end of coil 2 is connected to the two cathodes 4 and 5 ‘of the thermionic vacuum tube 3. Cath odes 4 and 5 may be a single common cathode In the past most recti?ers have been connected so that when a modulated radio frequency volt age is fed to the input, an output consisting of useful demodulation‘ products, direct current, since they are connected together. The other radio frequency and radio frequency harmonics is produced. The undesired direct current is usually removed by means of capacity coupling 25 to vfollowing circuits and the radio frequency and ‘its harmonics are ?ltered out. The capacity coupling attenuates the low frequency desired end of coil 2 is connected to the two plates or anodes (Sand 9 thru independent load circuits. The anode end of coil 2 is‘ connected to anode 6 of‘tube 3 thru the impedance of resistor "l ‘paralleled by condenser 8. Anode 6 is also con nected to reference potential or ground point G. demodulation products and the "radio frequency The anode end of coil 2 is also connected to the ?ltering attenuates the high frequency desired second anode 9 of tube 3 thru the impedance of resistor If] and condenser H .in parallel. An “output device” which willusually be an audio ‘frequency ampli?er, is connected between anode 9 and ground or reference point G at [2 and I3 output to a greater or lesser extent depending on the precautions taken. My present systemv is simple and yet produces less attenuation of low and high frequency demodulation products than most circuits by balancing out the direct current C: CA and radio frequency voltages rather than ?lter ing them out. ‘ respectively. My system consists of a double diode, or two Across one load circuit no desired de modulation products are developed while across the other load circuit the full range of desired demodulation products is developed. In the out-‘ put circuit the drops across the two load circuits 45 ‘are subtracted, cancelling out the direct current and radio frequency voltages but producing an 'unattenuated full range of desired demodulation across coil 2 varies as in the case of a modulated radio frequency voltage, condenser 8 discharges thru resistor 1 when the voltage decreases and charges thru ‘the diode consisting of cathode 4 and anode B when the voltage increases. How 45 completely the recti?ed voltage across condenser 8 follows the modulation of the voltage across coil 2 is determined by the product of the ca— products. The appended claims set forth, in particular, pacity of condenser 8 multiplied by the resist the novel features to- be found in this invention. ance of resistor l and the frequency of the volt 50 age change. The above condition also holds for The following description, however, when taken in connection with‘. the drawing, will serve to the voltage appearing across condenser E i. Spe set forth the theory and mode of operation of 55 my invention.’ ' _' In the drawing, ‘ ' ‘ ' . When a voltage is induced in coil 2, recti? cation takes place due to the action of the diodes 35 formed by cathode 4 and anode 6 and by cathode 5 and anode 9. The recti?cation causes con densers 8 and H to charge up to the peak value of the voltage appearing across coil 2 less the drop across the rectifying diode. If the voltage similar diodes, developing similar direct current and radio frequency voltage drops across two load 40 circuits. 0 ci?cally, if . - t E ‘ - . . 55 2 2,129,726 equals about one tenth, then about ten percent of the voltage change across coil 2 will appear is adapted to direct automatic volume control by using the drop across condenser 8 since the coil across the load circuit while if 3 CT is about eight or greater, the load drop will almost completely follow the voltage variations across coil 2. In the above formula t is the time of one period of the voltage variation, 0 is the capacity of the load condenser and 1' is the re— sistance of the load resistor. Ill paralleled by condenser ll. Cathode 4 is con nected to the reference potential point G. Fig. 2 - Fig. 3 shows a conventional modulated wave with the modulation envelope shown. The line 0 represents the average of the radio frequency voltage, b the peak amplitude of the modulated wave and a the modulation envelope. Now, if end of condenser 8 is negative with respect to ground G and may be connected by lead I5 to the control grids of amplifying tubes preceeding or following the recti?er. Switch I4 is shown to open or close the discharge path of condenser 8 thru the resistor ‘I. If this recti?er is used in a 10 radio receiver, switch 14 may be opened for tun ing purposes since it permits the build-up of automatic volume control voltage in accordance with the strength of the signal being tuned in and since no discharge path is provided, holds the 15 sensitivity of the receiver constant during tuning. Under these conditions the receiver may be tuned by ear since the true selectivity is not obscured by the action of the automatic volume control as 20 for condenser 8 and resistor ‘I of Fig. 1 at the lowest modulation frequency is one tenth or less, the voltage across condenser 8 will be maintained substantially equal to ob the peak of the modu lated wave since it will not follow the modulation envelope. Fig. 4 shows line d representing the voltage across condenser 8 under these conditions where 011 equals ob of Fig. 3. Now, if t 30 for condenser H and resistor I0 is eight or more for the highest modulation frequency, the volt age across the condenser H will follow the mod ulation envelope of Fig. 3. The voltage across condenser l I is shown by the difference between d and e of Fig. 4. If point G at anode 6 is taken as a reference point, the coil end of condenser 8 will have a voltage 0d with reference to point G and the voltage across condenser II will sub tract from the voltage across condenser 8 leaving a net voltage between anode 9 and ground G equal to ac as shown in Fig. 4. This net recti?ed out put voltage shows the cancellation of direct cur rent in such a way that, except for sudden changes in modulation, the negative peaks are always on the zero axis. This permits direct conductive coupling of the detector to a follow ing tube as shown by grid H5 in the “output de vice” of Fig. 1. Also, since the radio frequency voltage drops across the two resistor-condenser loads are opposed. the radio frequency voltage in the output is less than that in simple diode circuits. This direct coupling and reduced radio frequency permits reduced attenuation of both low and high modulation frequencies over conven tional recti?er circuits. The coil end of resistor ‘I may be used as a source of automatic volume control voltage although in general phase re versing means will be necessary. The circuit shown in Fig. 2 is similar in theory and operation to that of Fig. 1 except that the recti?cation products are reversed in phase. Fig. 5 shows curve J‘ as the drop across the larger time constant load circuit, curve in the drop across the other load circuit and oh the net out put voltage between cathode 5 and ground G. This output is similar to the output from the circuit of Fig. 1 except for the reversal in phase. This reversal in phase is accomplished in Fig. 2 by interchanging cathodes and anodes of the two diodes. Anodes 6 and 9 are connected directly to one end of the input coil 2 while cathode 4 is con nected to the other end of coil 2 thru resistor T paralleled by condenser 8, and cathode 5 is con 75 nected to the cathode end of coil 2 thru resistor described in my copending application Serial No. 20 25,390 ?led June 7, 1935, entitled “Automatic sensitivity tuning.” Switch vl4 may also be used for the same purpose in series with resistor 1 of Fig. 1. The circuits of both Fig. 1 and Fig. 2 may be 25 used as control circuits in various ways. For in stance if resistor 1 is heavily by-passed for modu lation frequencies and resistor I0 is somewhat less heavily by-passed, the output of the rectifier will be a low frequency wave representing the slow changes in average modulation which may be useful as an automatic control voltage. A choice between the connection of Fig. 1 and Fig. 2 will yield the desired phase of control voltage. This form of recti?er may also be useful in expansion 35 circuits on account of its property of frequency component selection. While thermionic vacuum tubes have been shown and described as rectifying elements, other types of recti?ers may be used such as crystals or 40 copper-oxide combinations. While I have described only a few systems whereby my invention may be carried into e?ect and have pointed out only a few possible varia ‘tions, it will be apparent to one skilled in the art that many modi?cations are possible without departing from its spirit and scope as set forth in the appended claims. What I claim is: Li 1. In a carrier wave receiver, a rectifying cir 50 cuit including a common input impedance, a thermionic vacuum tube comprising at least one cathode connected to one end of said input im pedance and two anodes, each of said anodes being connected to the other end of said input impedance thru independent load circuits, a con nection between one of said anodes and a point of reference potential and a connection between the other of said anodes and an output device, wherein said load circuits are resistances shunted 60 by condensers, the time constant of one of said load circuits being substantially greater than the time constant of the other of said load circuits. 2. In a carrier wave receiver, a rectifying clr.. cuit including a. common input impedance, 2. rec- _ ti?er comprising two cathodes and two anodes, ' direct connections between said cathodes and one end of said input impedance, independent load impedances between each anode and the other end of said input impedance, means whereby one of 70 said anodes is maintained at a reference poten tial, an output circuit connected between the other'of said anodes and said point of reference potential, wherein each of said load circuits ex hibits a substantially different time constant. 3 2,129,726 3. The method of generating modulation fre quency voltages which comprises generating a direct current voltage proportional to the peaks of a modulated radio frequency wave, generating a second voltage proportional to the instantane ous value of the modulation envelope of said modulated radio frequency wave said second volt age comprising a modulation frequency com ponent and a direct current component and sub tracting one of said voltages from the other of said voltages to produce a modulation frequency voltage resultant having substantially no direct current component. 4. In a carrier wave receiver, a rectifying cir cuit including a common input impedance, two pairs of rectifying elements, a low impedance cir cuit between two similar rectifying elements and one end of said input impedance, independent load circuits connected between each remaining 20 rectifying element and the other end of said input impedance, means whereby a direct cur rent path in one of said load circuits may be opened, and additional means whereby one of said rectifying elements connected to one end 25 of one of said load circuits is maintained at a reference potential. I ; 5. In a carrier wave receiver, a rectifying cir cuit including a common input impedance, a rec ti?er comprising two- cathodes and two anodes, a low impedance circuit between said anodes and one end of said input impedance, independent load circuits between each of said cathodes and the other end of said input impedance, means whereby one of said cathodes is maintained at a '?Xed reference potential and an output device connected between said two anodes, wherein said load circuits differ substantially in audio fre quency impedance. 6. The circuit as set forth in claim 5 wherein 40 said point of reference potential is ground. 7. The circuit as set forth in claim 5 wherein each of said load circuits exhibits a substantially different time constant. 8. In a carrier wave receiver, a rectifying sys tem including a source of unrecti?ed voltage, two pairs of rectifying elements, a low impedance connection between two similar rectifying ele ments and one end of said voltage source, inde pendent load circuits connected between each re 50 maintaining rectifying element and the other end of said voltage source, a low impedance connec tion between one of said load connected rectify ing elements and a point of ?xed reference po tential, means applying the voltage drop across the load circuit connected to said point of ref erence potential to gain control means in said receiver and additional means whereby a direct current path may be opened in the last said load circuit. 9. In a carrier wave receiver, two recti?ers receiving carrier wave impulses and producing output currents in two independent load cir cuits, an output circuit receiving the combined it) voltages developed across said load circuits con nected in opposed polarity, in which the audio frequency impedances of said load circuits are substantially different. ‘ 10. A circuit for generating a. ?rst demodula 15 tion voltage proportional to a carrier wave am. plitude and a second demodulation voltage con sisting of audio carrier modulation, comprising two non-linear electrical conductors receiving modulated carrier voltages and each producing an 20 independent output current in independent load circuits, wherein the audio frequency impedance of one of said load circuits is substantially less than the‘other and means combining the de modulation voltage drops in opposed sense to 25 form a useful output. 11. A circuit as described in claim 10 wherein each of said load circuits comprises a resistor shunted by a condenser and further means com prising a switch in series with one of said re sistors. 30 12. In an automatic volume controlled ampli ?er the combination of a recti?er including at least a cathode and an anode, a circuit connected between said cathode and said anode including 35 at least a signal responsive circuit and a series connected condenser and a circuit shunting said condenser including at least a resistance and a switch connected in series. 7 - 13. In an electrical ampli?er the combination 40 of a grid controlled thermionic ampli?er tube, a pair of rectifying elements, a load circuit compris ing a resistor and a parallel connected condenser‘ connected in series with each of said rectifying elements and an input circuit, a low impedance 45 conductive connection joining one end of each of said load circuits, a low impedance conductive ground connection to the other end of one of said load circuits and a low impedance conductive connection between the other end of the other of 50 said load circuits and the grid of said ampli?er tube. ALFRED W. BARBER.