* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
Download pat2505254_mesner.pdf
Schmitt trigger wikipedia , lookup
Mathematics of radio engineering wikipedia , lookup
Crystal radio wikipedia , lookup
Loudspeaker wikipedia , lookup
Oscilloscope history wikipedia , lookup
Power electronics wikipedia , lookup
Operational amplifier wikipedia , lookup
Switched-mode power supply wikipedia , lookup
Phase-locked loop wikipedia , lookup
Opto-isolator wikipedia , lookup
Standing wave ratio wikipedia , lookup
Superheterodyne receiver wikipedia , lookup
Transistor–transistor logic wikipedia , lookup
Regenerative circuit wikipedia , lookup
Audio crossover wikipedia , lookup
Public address system wikipedia , lookup
Electrical ballast wikipedia , lookup
Wien bridge oscillator wikipedia , lookup
Two-port network wikipedia , lookup
RLC circuit wikipedia , lookup
Equalization (audio) wikipedia , lookup
Index of electronics articles wikipedia , lookup
Resistive opto-isolator wikipedia , lookup
Radio transmitter design wikipedia , lookup
Zobel network wikipedia , lookup
April 25, 1950 2,505,254 M. H. MESNER TONE CONTROL CIRCUIT Filed Sept. 7, 1944 70 Jb6P.C. OF 7N ' I ATTO R N EY Patented Apr. 25, 1950 2,5105,254 T OFFICE UNITED STA 2,565,254 TONE CONTROL CIRG Max H. Mesner, Princeton, N. J., assignor tn Ptadio Corporaition of America, a corporation of Delaware Application September 7,1944, Serial No. 553,024 11 Claims. (Cl. 179-1111 My preseiit invention 1 2 conjunction wiili the adjustable element of the tone control device. generally. to freenGy discriminatory and more parularly to a n improved audio fzequency tone iri nals in a wide range 01 frequencies. Furthermore, Lhe source of signals for the network may cior output of a radio receiver, the of apublic address system, the pickup reproducing device, a n audio freC L E ~ C Y sipl?al distribution line or-even the video signal transmission network of a -television r+ csiver. For $the.purpose-of the present application, however, it is assumed that the -source of slgnd voltage is a n audio frequency voltage source. The nunzerai 1 designates an electron discharge tube which is shown by way of illustration as 8 triode type. It is to.be clearly underof tube may be em20 e numeral 5 denotes the low potential or ground lead of the input circuit. The cathode 6 of tube 1 is connected to ground th usual grid bias network 7. The grid sistor-8 is,connected from the output terminal of folcondenser 3 to ground. The plate 9 of tube 1 is 30 comected to the +B terminal of a source of direct current (not shown) through the output load resistor 10. Those skilled in the art of radio communication are fully aware of ,the nature of the direct current supply source -which may be 35 employed with a system of the type shown in 2j connected to the g tube whereby o Fig. 1. 40 its input electrode or grid 12 connected to the direct current blocking condenser 6 3. The input terminal of the latter i s connected best be ead-of resistor I D . The cathode 14 connected to ground through the grid biasing resistor 15, bypassed in suitable manner for alter60 naiing currents. The direch current return resistor path for grid 62 consists of resistor R1 and that portion carried into effect. of resistor R included between the grounded adIn the drawing rejustable slider 16 and the lower end of resistor 55 R. The grid. return resistor path performs a dotrhle function in my invention, and it is a n my invention; essential p a r t of the tone control device. Fig. 2 shows various-respanse .curves secured r end of resistor R is connected by for various settfngs of thee B ' P to the input ferminaltof condenses 13. and be seen, therefose, that adjustmept of Fig. 3 iKlustra&s;a;diaI;mrh 45 2,605,254 4 3 slider or tap B Ei along resistor R varies concurcounterclockwise path of the potentiometer range, higher audio frequencies are attenuated to a rent$ the magnitlide 01 resi5tance in series with greater or lesser degree depending 02 the amount condenser 11 beheen the plate circuit of tube I of resistance to ground that is placed in series and ground, aiid also the magnitude of resistance between the grid circuit of tube 1 1 and ground. 5 vJith condenser 17. For the higher audio frequencies the impedance of condenser C T plus the The plate circuit of tube 1 t i s completed in the resistance in series therewith becomes low encugh usual manner. The signal voltage amplified by tube 1 I is developed across load resistor 18. The sufficiently to lower the plate load resistance 10. amplified signal voltage transmitted to output The impedance of condenser 17 at higher than leads 19 will have its frequency response charac- !I? any chosen cut-off frequency should be nearly as small as, or smaller than, the impedance of t i e teristic dependent on the adjustment of slider 16. The utilization means may be a loudspeaker, amload resistor 10. That is, of course, true f x counterclockwise positions of slider $ 6 . This replifier or the like. By way 5f specific illustration, the following values of the above-recited elements duces the gain of tube I for the higher audio frehave been used in a successful embodiment of the ;i quencies. The value of resistor R is chosen so that when invention. My invention, however, is not limited the slider 16 reaches the midpoint on R, the reto use of these particular values. sistance in series with condenser 1’8 is sufficiently Resistor IQ=33,000 ohms high in comparison to the load resistance 1 i3 that R1=lOO~OOO Ohms y its shunting effect even a t higher audio 3cquenR = l megohm cies becomes negligible. This midpoint on posiPlate resistance of tube B =8,000 ohms tion 5 of indicatGr 20 is the “high fidelity” region, ‘Ondenser 1’1=0*025microfarad where the tone control has no effect a t either the ‘Ondenser L3=0*005 microfarad high or low frequency end. This is best illusExplaining, now, the functions of the elements 2.5 trated in pig. 2 wherein the frequency response curve corresponding to position 5 of indicator 20 of the tone control device, it is pdnted out that the latter cons&tso; a simple potentiometer havPOSSeSSeS substantially uniform tranSmiSSiOII Of audio freClUenCy currents above 100 cycles with ing three terminals. atyo of these ternlinals a arid b are connected provide a variable attenuminimum attenuation of currents below 100 ation path for the higher audio frequency cur- 3! If the slider 16 is moved closer to the lower end rents. The thi1.d terminal c is connected to the C Of the resistor R,that is clockwise, the resistlower end of the grid return resistor R ~ . The ance from grid to ground becomes less. For values of coupling condenser 13, grid return rethe midpoint Position Of slider 16, the resistance &tor R~ and the overall resistance R of the POtentiometer are SO chosen that the time constant ‘:? Of Ri PIUS half Of the resistance O f R is the factor of the intertube coupling circuit is c:itically variwhich Controls the Value Of condenser 13. The capacity Of condenser 13 is chosen so that the able over half the range of the adjustable element 16. time constant (i. e. the RC product) is great enough t o J a S s low audio frequencies down to The %tion of the tone control device be analyzed in the light of the experimental Curves !I) the lowest audio fRqUenCY required for high fidelity. As the maximum clockwise position is of Fig. 2 and the illustrative control dial of pig. 3. reached the time constant b.ecomes less thereby In Fig. 2 I have shown various frequency response curves experimentally secured for various settings causing the low frequency range to be curtai!ed. At the extreme clockwke position of slider 16, of the tone control adjustable element 16. “Response in decibels” is plotted against “Frequency J S that is Position 10 O f indicator 20 in Fig. 3, the bass character is determined by the magnitude OP .hcycles per second.” CoUPling condenser 13 and resistor R1. The magIn Fig. 3 there is shown an illustrative dial that may be used in conjunction wit11 the adjustable nitude Of resistor RI is thus chosen to give the maximum frequency range reduction required. element 16. Let it be assumed that potentiomIt is Preferred to choose the magnitude O f Ri SO eter slider 16 is rctated in an arc in sliding conthat it is COmparatiVelY large with relation to the tact with the resistor R. In such case the indicator or pointer 25 would be mechanically coupled load resistance 10. The reason for this relation is that the tone control device will have a minit o element 16 for motion therewith. A t position 1 of slider 16 (extreme CQUnterclockwisepwition) mum effecton the general Volume level. This can the slider will be located at the upper end of re- Y’i best be accomplished by choosing the resistance Of load 10 as low as the amplification require&tor R. At position 10 in Fig. 3 (extreme clockwise position) the slider is located at the terminal ments W i l l allow. The impedance of condenser c of resistor R. Position 5 of the indicator 20 13 at low audio frequencies should fie as great, or greater than, that of Ri. Hence, at such frecorresponds approximately to the midway position of slider I 6 on resistor R. It will be noted 4’’ ~UenCiesthere will be a definite amount of voltage that position 1 is the “Treble attenuation” point; division a t the grid terminal. position 5 is the “High fidelity” setting; setting From the experimental curves of Fig. 2, it will be seen that when slider f 6 is adjusted to posi10 is the ‘‘Bass attenuation” adjustment. Fig. 2 relates these three settings On the frequency retion 1 in Fig. 3 there will be maxiraum attenuasponse curves. Further, the response curves of ‘5 tion Of the higher audio irequencies, with no Fig. 2 are numbered to correspond to the tone effect on the lower audio frequencies. Adjustcontrol settings of Fig. 3. ment to position 2 of Fig. 3 results in substanIt will be observed that when the slider 16 in tially the same frequency response curve. SUCFig. 1 is adjusted to the upper end of resistor R, cessive adjustments to positions 3 and 4 result there will occur maximum bypassing of higher 70 in successive decrease of attenuation in higher audio fFXlUenCieS. At the midpoint 5, as stated audio frequency currents. In this position of the before, there occurs optimum transmission over slider the condenser 17 connects the plate circuit of tube 1 directly to ground, and no portion of the entire signal frequency range. Further adjustment of the slider to positions 8, 9 and 10 resistor R is included in circuit with the condenser. When the slider is adjusted in the 75 in succession results in increased attenuation of ’* 1 aftknuatibn of lower audio fIWUenpiing the plate end of said output load resistontrol device i0 ance to said control grid, a potentiometer havi ~ an g adjustable contact connected to ground, the median setting. a Second condenser of relatively low impedance - to higher audio frequencies connected in series from the plate end of said outDut load to one 16 end of saia potentiometer and through said cont ground, a resistor OP fixed ma ‘C d from ‘said control grid to th e aid potentlometer whereby said gria is returned to ground through said fixed magnitude resistor and a portion of said potenssion tiometer, said fixed magnitude resistor befng and comparatively large relative to said output load miresistance so that variation of said potentiome%er will have a minimum effect on the volume and and 25 level a t the output of the second amplifier tube. output terminals being connected Go a common 5. In a system as defined in claim 2, said fist etwork which in“condenser having an imQedance a t low audio fretor connected bewhich is ‘at least as great as the imof said resistor of fixed ma tween said one input terminal and one end o i system as defined in claim 2 a potentiometer having a n adjustable contact :so ond condenser having a n impedance which, at arm, and a fixed resistor connected betweelz said higher than any chosen cut-off frequency, is a t one output terminal and the other end of said least as small as the impedance of said output potentiometer, said contact arm being connected load resistance. to said common point. 7. I n combination with an audio frequency 2. In combination with an audio frequency 35 signal transmission network provided with a pair signal amplifier tube provided with a n output of input terminals and a pair of output termiload, a second amplifier tube provided with a t nals and a coupling condenser connected beleast a cathode, a control grid and an output tween one of said input and one of said output electrode, a first condenser of low impedance to high audio frequency currents coupling the 40 terminals, a n adjustable attenuation network connected in shunt across the transmission netplate end of said output load to said control grid, work, said attenuation network consisting of a a potentiometer having an adjustable contact compensating condenser having a relatively low connected to ground, a second condenser of relaimpedance at the upper end of the audio fretively low impedance to higher audio frequencies connected from the plate end of said output 4.5 quency range connected between said one input terminal and one end of an adjustable potenload to one end of said potentiometer, and a retiometer resistor having a movable contact consistor of fixed magnitude connected from said nected to the other input and output terminals, control grid to the other end of said potentiomea second attenuation circuit including said couter whereby said control grid is returned to ground through said fixed magnitude resistor 50 pling condenser, said coupling condenser having a relatively low impedance to said high freand a portion of said potentiometer. quency end of the signal frequency range, and a 3. In combination with an audio frequency connection between said one output terminal signaI amplifier tube provided with an output and the other end of said potentiometer, the load, a second amplifier tube provided with a t least a cathode, a control grid and a n output 55 magnitude of the resistance included in said second attenuation circuit being directly dependent electrode, a first condenser of low imoedance to upon adjustment of said movable contact, and high audio frequency currents coupling the plate the impedance of said coupling condenser a t low end of said output load to said control grid, a audio frequencies being chosen to be nearly as potentiometer having a n adjustable contact 60 great as,or greater than that of the resistance inconnected to ground, a second condenser of relacluded in said second attenuation circuit a t any tively low impedance to higher audio frequencies ,position of said movable contact. connected in series from the plate end of said 8. In combination with an audio frequency output load to one end of said potentiometer signal amplifier tube provided with a n output reand through said contact to ground, a resistor 65 sistor, a second amplifier tube provided with at of fixed magnitude connected from said control least a cathode, a control grid and an output grid to the other end of said potentiometer electrode, a first condenser of low impedance t o whereby said control grid is returned to ground high audio frequency currents coupling the plate through said fixed magnitude resistor and a porend of said output resistor to said control grid, tion of said potentiometer, the overall resistance 70 a second condenser of relatively low impedance value of said potentiometer between the ends to higher audio frequencies connected in series with a first variable portion of a potentiometer thereof being very high compared to that of the fixed resistor whereby the lower audio frequenresistor from the plate end of said output recies are not attenuated until after a substantial sistor to ground, a resistor of fixed magnitude portion of the resistance of said potentiometer is 75 connected from said control grid to said poten- 7 %,am,mrP 8 tiometer resistor whereby said control grid is re11. The combinaiton set forth in claim 1 In turned to ground through said resistor of fixed which the time constant of the resistance of said magnitude and a second variable portion of said fixed resistor plus one-half the resistance of said Potentiometer with the capacitance of said COLIpotentiometer resistor, the overall resistance of said ,potentiometer resistor being chosen very 5 pling capacitor is so related to the lowest frehigh compared to that of the fixed magnitude quency of the signal frequency range that said resistor whereby the lower audio frequencies are lower frequency is passed through said network not attenuated until after a substantial portion substantially without attenuation. of the resistance of said potentiometer resistor MXX H. MESNER. is included in series with the second condenser 10 REFERENCES CITED to ground, said fixed magnitude resistor also being large compared to said output resistor. The following references are of record in the 9. The combination set forth in claim 1 in file of tihis patent: which said compensating capacitor has a relaUNITED STATES PATEINTS tively low impedance at the high frequency end 15 Number Name Date of the signal frequency range and in which the Aceves ____________ Dec. 18, 1934 1,984,450 overall resistance value of said potentiometer is such that when said contact arm is centered 2,065,344 Newton ____________ Dec. 22, 1936 Dyksterhuis Jan. 5, 1937 on said ootentiometer the resistance in series 2,066,676 Lansing ___________ Jan. 26, 1937 with said Compensating capacitor is sufficiently 20 2,068,685 2,113,332 Morse et al. ________ Apr. 5, 1938 high that the loading effect of said compensat2,121,150 Jarvis ____________ June 21, 1938 ing capacitor on said network is neligible. 2,264,715 Rohr _______________ Dec. 2, 1941 10. The combination set forth in claim 9 in 2,433,330 Atkinson __________ Dec. 30, 1947 which the time constant of the resistance of said fixed resistor plus one-half the resistance of said 25 FOREIGN PATENTS potentiometer with the capacitance of said couNumber Country Date pling capacitor is so related to the lowest fre699,749 Dec. 16, 1930 France _____-______ quency of the signal frequency range that said lowest frequency is passed through said network substantially without attenuation. 30 ________