Патент USA US2404101код для вставки
¿Qi? 16, 1946'. R. E, scHocK ïßmßìm ~ REMOTE SQRT-ROL OF RADîQ BECEIVERS Filed April l5, 1942 _E P favors cour/ML Öse/¿4,4701? l -iß«fl #055191“ E. Jef/0cm @Y f ' ATTQRNEY July 16, 1946. R. E. scHocK 2,404,101 REMOTE CONTROL OF RADIO RECEIVERS Filed April 15, 1942 5 Sheets-Sheet 2 n m+ N w è N .mi INVENTÓR ROBERT E. Sch/och’ BY ATTORNEY My 16,' 194s. R. E. SCHOCK ' www@ ` REMOTE CONTROL'OF RADIO‘ RECEIVERS Filed' April 15, 1942 REVS/@Le _ 9 l 5 Sheets-Sheet 4 i J SuYm; July 16, 1946. R. E. scHocK 2,404,101 REMOTE CONTROL 0F RADIO RECEIVERS Filed April 15, 1942 I 5 SheetSI-Sheet 5 1:1 -à INVENTOR /PoßE/i‘r E. âcHoc/r ATTO R N EY Patented July 16, 1946 2,404,101 UNITED STATES PATENT OFFICE 2,404,101 REMOTE CONTROL OF RADIO RECEIV ERS Robert E. Schock, Riverhead, N. Y., assignor_ to Radio Corporation of America, a corporation of Delaware Application April 15, 1942, Serial No. 438,979 14 claims. (C1. Z50-20) 1 2 My present invention relates to novel and im proved methods of remotely controlling a radio receiver, and more particularly to a novel method by way of illustration, the remote control oscil lator comprises an electron discharge tube hav ing a tank circuit comprising coil 2. The cath of, and apparatus for, controlling tuning and/or ode, or ñlament, is energized by source F, while direct current source P supplies the positive plate potential. It will be recognized that the oscil lator is of the well known Hartley type. The coil 2 may be resonated to different control fre quencies by choice of a proper tuning condenser. volume of radio receivers from a remote point. Certain types of remote control tuning systems, introduced in the past in the broadcast receiver field, use an oscillator at the controlling point. The oscillator is made to send out signal pulses for the purpose of controlling the tuning and/or volume at the receiver. Such systems are not readily adaptable to either push button tuning Thus, a desired one of the plurality of iixed con densers c, y, œ and a may be shunted across coil 2. Push-button control may be had at the oscillator by providing a plurality of normally or continuously variable tuning. The ideal open switches 3, 4, 5 and 6. Each switch, upon method of remote control should be adapted to either push button tuning, or continuously vari 15 closure, effectively shunts its associated con able tuning. denser across coil 2, and simultaneously com pletes the iilament and plate circuits. Of course, Accordingly, it is one of the main objects of each of condensers c, y, :r and a, is of a different my invention to provide a remote control method magnitude. wherein the remote controlling device is an oscil lator whose frequency may be changed at will 20 Tuning push-buttons 3', 4', 5', 6’ are- pro vided for the respective switches. These buttons by the operator, and wherein the controlled de 3' to 6’ correspond to frequencies fc, fy, fx and- fa vice incorporates a frequency discriminator cir respectively. In other words, actuation of a cuit Which detects the frequency changes of the button to close its respective switch results in controlling oscillator and causes these changes to direct the operation of the controlled device. 25 production of constant amplitude oscillations of the selected frequency. For example, depression Other features of. my invention will best be of button 6' results in production of oscillations understood by reference to the following descrip of a frequency fa. The control oscillations may tion taken in connection with the drawings in be radiated through space to the controlled ap which I have indicated diagrammatically sev eral circuit organizations whereby my invention 30 paratus, or the oscillations may be transmitted thereto by a transmission line. Let it be as may be carried into effect. sumed that the oscillations are radiated. Fur In the drawings: thermore, the frequency of the oscillations can Fig. l shows a remote control oscillator em be in any desired frequency band. However, bodying the invention, the intensity of the generated control waves Fig. 2 shows a motor control circuit adapted ` should not be such as to cause interference with to respond to the oscillator of Fig. 1, other receivers in the vicinity. Fig. 3 shows the characteristic of the discrim At the controlled point there may be located inator-rectiiier of thev control circuit of Fig. 2, Fig. 4 illustrates a modification of the circuit of Fig. 2, Fig. 5 shows the operation of the> circuit in Fig. 4, Fig. 6 shows the circuit details of the motor control circuit for tuning and. volume control, and is adapted to be inserted between- points P and Q of Fig. 2, Fig. 7 shows a modified form of remote oscil lator wherein separate tuning and volume con trol push~buttons are used. Referring, now, to the accompanying draw ings, it will be understood thatv like reference> characters in the different figures designate similar circuit elements. The control instru-> mentality is an oscillator, shown in Fig. 1,Y whose circuits may be of any well known form. Merely a radio receiver which is to be regulated in ac cordance with the frequency of the control oscil lations. The regulation may be with respect to tuning or volume, or any other characteristic. In Fig. 2 there is shown a system for adjusting automatically the tuning of a receiver. The ad justing mechanism is a reversible control motor *25 provided with a drive shaft 25'. It will be understood that shaft 25’ is mechanically cou pled to the receiver tuning device (not shown). The condenser gang shaft (not shown) may be 50 geared to the shaft 25’ in any desired fashion. The motor 25 is supplied with energizing cur rent by leads 30’. One of these leads 30’ is con nected to one terminal of the motor by a switch 3D. The second leadv 36' is connected to the piv 55 oted arms, or contactors, of independent switches 2,404,101 "D 4 24’ and 23’. The fixed contact of switch 23’ is connected by lead 23” to the third terminal of motor 25, while lead 24" connects the iixed con tact of switch 2d’ to the intermediate terminal of the motor. There will now be described the whose magnitude and polarity are as indicated ¿n at Fig. 3. various high frequency circuits for controlling the diii‘erent motor circuits. ` The point P is connected by resistor I E to the junction of direct current sources I6 and I'I. The right hand end of resisto-r l5 is con nected to ground by a condenser l5'. The po tentiometer resistor I8 is connected between the positive terminal of source ES and the negative _ The receiving system for receiving the control terminal of direct current source i7, and the mid waves is essentially similar to the well known automatic frequency control (AFC) system used ._10 „point of the potentiometer is connected to the for superheterodyne receivers. Thus, the con~ ' junction of the two current sources. The po tentiometer resistor I8 is provided with an ad justable tap Q, and the control grid of tube I9 is connected to the potentiometer adjustable tap. frequency oscillations. The ampliñers maybe 15 The tap Q is mechanically coupled, by any de sired mechanical linkagel to the motor shaft. of well known construction, and need not be de Such linkage is indicated schematically by the scribed in detail. The resonant input and out~ dotted line 3|. The cathode of tube I9 is con put circuits S1 and S2 oí amplifier T1, and the nected in common to the cathode of the follow resonant input and output circuits S3 and Si of amplifier T2, are tuned to pass all the control 20 ing tube 20, and the control grid of the latter is connected to the grounded end of the cathode frequencies which may be employed. In other resistor 20’. The plates of both tubes I9 and 20 words, the tuned ampliñers will be sufficiently are supplied with positive potential from the broad up to circuit Si so as to pass efficiently the trol waves are collected by the collecting device T. The waves are then passed through cascaded amplifiers T1 and T2. These amplify the radio oscillations of any selected control frequency. ` The discriminator-rectifier comprises the di plus B terminal of the main direct current source It will be noted that the plates of tubes i9 and 20 are connected to opposite ends 25 (not shown). odes 9 and I@ whose cathodes are connected by series-related resistors il and l2. Each of the of the winding of the electromagnet 23 which controls switch 23’. In other words, when the latter is -by-passed for alternating currents, while the cathode end of resistor I2 is grounded. The 30 winding of electromagnet 23 is energized, then switch 23’ is closed. cathode end of resistor il is designated as P; Switch 24’ is controlled by an electromagnet the motor control voltage is derived from point 24. The energization of the electromagnet wind P. The common input circuit of the rectifier di ing depends on the action of tubes 2I` and`22. odes consists of a tuned circuit i3, One side of The control grid of tube 2I is connected to the the latter is connected to the anode of diode 9, adjustable tap Q. Each of tubes 2I and 22 has while the anode of diode it connects to the op its cathode connected to ground through a re posite side of the circuit i3. The numeral 'l de spective cathode biasing resistor. The control notes the primary winding of the transformer grid of tube 22 is connected to the cathode of whose secondary is composed of sections i3’ and tube 2 I, and the plates of the tubes are connected I3” >each coupled to the primary. The junction 40 to opposite ends of the winding of electromagnet of the sections BSV-I3” is connected by direct 24. It will be noted that the common lead 22’ current blocking condenser 8 to the high alter supplies plate potential to each of the plates of hating potential side of circuit S4. The junction tubes I9 to 22 inclusive. The network I9 to 22 of resistors Il and l2 is returned through choke inclusive functions to provide a keyer circuit actu coil I4 to the junction of coil sections ISL-i3”. 45 ated by the voltage variation of point P. The The plates of amplifiers T1 and T2 are connected keying circuit functions to key either of relays by a common lead L to the source of positive po tential +B. The circuit i3 is tuned to a fre 23--23’ or 2li-24', as directed, for the purpose of determining the direction of rotation of the re quency which is at the middle of the control fre- 4 versible motor 25. quency range. That is to say, the voltage dif 50 A further keyer circuit is provided to close ference between point P and ground is Zero at switch 30 whenever there is a control signal at the the -said frequency of circuit i3. It is pointed receiver. Thus, tube 28 has its plate connected to one end of the winding of electromagnet 29, out that the present discriminator-rectiñer while the opposite end of the winding is connected S4-I3-9-Iû is essentially of the type `shown by S. W, Seeley in his U. S. Patent No._2,l2l,l03, 55 to the cathode of the tube through resistor 28’. The cathode of- tube 28 is connected to ground granted June 21, l938._ The network acts to de through resistor 28". Resistor 28’ together with tect frequency changes in the control waves, rela resistor 28" constitute a Voltage divider by means tive to the aforesaid median frequency value, and of which positive voltage is supplied from the converts such changes into corresponding direct current voltage changes at point P. . 60l direct current source (plus B) to the cathode of tube 28 at a magnitude which will properly bias tube 28. When the winding of electromagnet 29 is energized switch 30 is closed. The control grid of tube 28 has its potential regulated by the diode abscissae are plotted against “voltage of point 65 rectifier 21. The anode of the latter is coupled by condenser 2'I’ in series with condenser 2'I” to P” as ordinates. The point B on the curve repre the junction of coil sections I3" and I3". The sents the median frequency point fe. This is the cathode of diode 2'I is connected to ground by frequency of circuit i3, and, as Shown, the volt» ` The curve of Fig. 3 shows how the Voltage across the resistors Ií-i2 (the potential differ ence between P and ground) varies with control frequency variation. “Control frequency” as resistor R, suitably by-passed for alternating cur rent components. The control grid of tube 28 is 70 frequencies fc and fy the voltages at point P are connected to the cathode end of resistor R. negative, whereas at frequencies fx and fa the A second diode 26 is arranged in parallel with voltages are positive. In other words, actuation diode 21. The diode 26 is supplied with control of a selected one of the buttons in Fig. 1 will wave energy from the input circuit I3 through automatically cause pointP to assume a Voltage coupling condenser 21”. The resistor 26’ func age of point P is zero. It will be seen that at 2,404,101 tions as a. load resistor for diode 26, the resistor being by-passed for alternating current compo nente. The anode end of resistor 26’ is connected to the low potential end of input circuit S3 through a filter resistor 26". In other words, the diode 26 functions as an automatic volume con trol (AVC) circuit for the amplifier feeding the dlscriminator-rectifier. The volume level at dis criminator input circuit I3 is maintained substan 6 at point P would have been positive instead of negative. As a result tubes 2l and 22 would have been caused to close relay switch 24’ instead of relay switch 23’. The motor would now run in the opposite direction causing the balancing po tentiometer tap Q to move to a position negative with respect to the voltage at point P. This would stop the motor as soon as this balance voltage were equal and opposite to the point P tially uniform in this manner. The AVC bias 10 voltage. The signal-operated relay 29-30 turns may be applied to tube T1, if desirable. the motor on" whenever the control signal is shut 'I‘he operation of the present remote control off. This prevents the control motor from oper system is best explained by first assuming the ating even though the voltage at point Q might remote control oscillator as operating at the mid not be balanced to zero in the no-signal condi frequency for which the control amplifier and 15 tion. discriminator circuits are tuned. This is repre It may be seen from the foregoing discussion sented by fB in Fig. 3. At this frequency the volt that for any frequency setting of the control oscil ages across the discriminator diode resistors II lator within the range of tuning of the dis and I2 are equal and opposite, and, therefore, the criminator circuit I3 (that is from points a to c voltage at point P is zero. For this condition, the 20 on the curve Fig. 3) there is a definite position motor-driven balancing potentiometer I8 is pur of the control motor (and the _balancing poten posely pre-set so that the voltage on the grids of tiorneter tap and receiver tuner mechanically tubes I9 and 2l (point B in Fig. 3) is also zero, linked thereto) at which the motor balancing and, therefore, neither relay 23 nor 24 is in opera potentiometer tap and receiver tuning device will tion and the control motor is inoperative. For come to rest. This makes it possible to calibrate this specific setting of control oscillator frequency, the controlling oscillator tuning mechanism and of the control motor, assume the radio re (either push-buttons or continuous) in terms of ceiver tuning is at a desired station frequency. It definite station tuning positions of the controlled will be understood that an extra button could be radio receiver tuning by proper alignment of the provided at the oscillator to produce the fre discriminator tuning, the balancing circuit volt quency fB. It would only be necessary to provide age supplies ( It and I? of Fig. 2), the balancing an appropriate condenser, and associated switch potentiometer I 3 and the receiver condenser drive. es as shown in Fig. 1. Now, to tune to a different station the remote control oscillator is tuned to a new frequency set ting, which by previous calibration is known to result in the tuning of the controlled radio re ceiver to this other station. For purpose of illus tration assume the new control oscillator fre quency is at point y on the curve of Fig. 3. In other words, push-button 4' has been actuated to initiate generation of oscillations 0f frequency fy. The circ-uit of Fig. 4 is a variation of that of Fig. In Fig. 4 the operation is the same, except for the method of balancing the voltage at point Q back to zero for each control frequency posi tion. In the circuit of Fig. 4, the balancing potentiometer circuit between points P and Q is eliminated, and the balancing is done by motor driven tuning of the discriminator circuit. The control motor 25 is mechanically linked to the discriminator circuit tuning condensers, as indi By inspection of the characteristic curve it is seen cated by the dotted lines marked 3 I '. The curves that the voltage resulting at point P of the dis of Fig. 5 show how the circuit of Fig. 4 works. crlminator circuit of Fig. 2 will now be negative. 45 Consider curve aBc to- represent the character This negative Voltage on the grids of tubes I9 and istic of the discriminator for normal mid-tuning 2I causes them to draw less current. Since the position where, for a control frequency of fe, current of tube I 9 nows through a cathode re the voltage at point P is Zero. _ sistor common to tube 2U, the decrease of current If the control frequency is now shifted in tun through this resistor decreases the grid bias of 50 ing for a different station, to a frequency fy tube 20. Hence, enough plate current flows to (point y on curve aBc), the voltage at point P operate relay 23, and the switch 23' of relay 23 will go negative. This will cause the keyer and is closed thus causing the control motor to relay circuit I8-2ll-23--23' to key the motor 25 operate. “on” as explained in connection with the opera However, since the cathode resistor of tube 2l 55 tion of the circuit of Fig. 2. However, in the furnishes grid bias for tube 22 the decrease of circuit of Fig. 4 the circuit is brought to balance current through the cathode resistor of tube 2I, and the motor stopped by causing the motor to due to the negative voltage on its grid, causes drive the discriminator tuning condensers I3a its cathode, and therefore the grid of tube 22, and |31) until the discriminator characteristic to go more negative. Hence, relay switch 24’ 60 4becomes that shown by curve a’B’c’ of Fig. 5. remains open. The control motor 25 would now At this position of discriminator tuning the fre operate continuously, were it not for the fact quency fn’ of the control signal no longer pro that it immediately adjusts the balancing poten duces a voltage at point P of Fig. 4, and, therefore, tiometer tap Q to a new position which, by virtue the motor keying circuit is released thereby stop of the circuit arrangement, brings the voltage at 65 ping the motor. Since the radio receiver tuning point Q back to zero. This will, in turn, cause condenser is also mechanically linked to this same switch 23’ to open and stop the motor. In other control motor it may be seen that the motor words, the circuit is so arranged that the poten driven discriminator tuning, if properly linked -tiorneter tap Q will always be adjusted in a direc and aligned, constitutes a balancing circuit which tion and to an extent such as to provide voltage to 70 will accomplish the same end as was achieved by balance, or buck out, the voltage from point P the motor-driven potentiometer voltage-balanc thereby causing the relay operating the motor ing circuit in Fig. 2. (either relay 23-23' or 2li-24') to stop the latter. In the circuits so far described, no provision If the tuning of the remote control oscillator was made for volume-controlling the receiver had been adjusted to a frequency fx, the voltage 75 from the remote control position. This may be 2,404,101 trol assume that the control frequency is shifted from the tuning range to the volume control of Fig. 2 between points P and Q, with the circuit range, for instance to frequency jv of Fig. 3. of Fig. 6. The balancing circuit of Fig. 6 is This, of course, makes point P slightly positive aligned with respect to the radio receiver tuning thereby biasing tube 5| to draw more current Cl and the remote control oscillator so that all of through its cathode. In turn, this biases the the receiver tuning is now accomplished within grid of tube 52 more positive thereby causing tube that frequency range of the control oscillator ly 52 to energize relay 53 and operate switches 51 ing between fß and fc of Fig. 3. This leaves that and 58. The operation of switch 58 to this vol frequency range of the control oscillator between ume control position energizes the gear shifting fa and J‘B of Fi-g. 3 for use in controlling volume relay |00 to disengage the tuning and balancing in the manner about to be described. drive shafts and couple the volume control drive It will be noted that so long as the control fre shaft |01 to the control motor. The switch 51 quency is held within the range fe to fc of Fig. 3, acts at the same time to cut out the balancing the radio- receiver tuning control range, the volt control circuit (|6’--|0’) and throws the nega age at point P in Fig. 6 is negative in polarity. tive voltage supply source 54 in series with the Tubes 5| and 52 of Fig. 6 form a keyer circuit lead connecting point P and point Q. which is so biased that if the control frequency is Since control frequency jv is between fx and shifted to the volume control range (fa to J‘B of fB (Fig. 3), point Q is rnow negative due to the Fig. 3) the voltage at point P is caused to go voltage supply source 54 being more negative positive. This will result in a shift of the two 20 than point P is positive at this control frequency. single-pole, double-throw switches 51 and 50 Therefore, tube I9 and its related relay keying from the position they were in for the tuning circuit (shown in detail in Fig. 2) is actuated control process, to the opposite side. As a con accomplished by replacing that part of the circuit sequence the circuit is set up for the volume control process thereby releasing the tuning con trol set-up in the following Way. Switch 51 cuts out the balancing potentiometer circuit |5’---|8', and connects in a voltage sup ply source 54 which is of such a value and polarity that it causes point Q to be negative , for any control frequency from fis down to a frequency fx midway between fa and je (Fig. 3). For any control frequency between fx and fa the positive Voltage at point P is greater than the negative voltage from source 54, and the point Q will, therefore, be positive. Later it will be shown how this feature renders the cir cuit usable for volume-controlling. Switch 53, when shifted to the volume control position, to operate the control motor as previously ex plained for the circuit of Fig. 2. Assume, now, that the motor-driven volume control is so ar ranged that for the above described condition it is being driven to increase the receiver volume. To decrease volume the control frequency is shifted to a fa (Fig. 3). Since fa is below ,fx the voltage at point P is now more positive than the voltage supply 54 is negative, and point Q is, therefore, now positive. This causes tube I9 and its related keying circuit to be de-energized, and tube 2| with its keying circuit to be ener giZed to reverse the direction of the control mo tor. As a result the volume control device is adjusted to decrease the Volume of the radio receiver. Therefore, operating the control fre quency at a frequency fv will increase the volume opens one relay and closes another relay in a 40 at the receiver, and operating it at a frequency circuit shown in detail in Fig. 6. fa will decrease the volume at the receiver. The switch 58 in the tuning position actuates Fig. 7 shows the control oscillator circuit of relay coil |0| which, acting through an arma ture |02 pivoted at |08, keeps the receiver tuning drive shaft |05 and balancing potentiometer shaft |06 geared to the control motor 25` through sliding shaft |03, and keeps the volume control mechanism disengaged from the control motor. Fig. 1 with provision for remotely controlling the volume at the receiver. To illustrate how the remote control oscillator of this modification works, suppose that it is arranged that buttons 3’-fi’--5’--5’ each correspond to points c-.e-y-B respectively of the curve of Fig. 3. When switch 58 is shifted to the left, or volume control, position it energizes relay |00. As a 50 These are the tuning buttons. They actuate the respective switches 3-5--5-6. The buttons result the gear shifting armature |02 disengages 300' and 500’ correspond to point o and a re the receiver tuning drive shaft |05 and the spectively of the curve of Fig. 3. Button 300’ balancing potentiometer drive shaft |55 from the closes switch 300, while button 400' is adapted control motor, and engages the volume control to close switch >400. The buttons 300’ and 400’ 55 drive shaft |01 to the control motor, The slid are the volume control buttons. ing shaft |04 is reciprocated by the lower end Suppose, now, it is desired to tune in a sta of armature |02.. It will be understood that tion for which purpose the circuit of Fig. 2 re shaft |05 is coupled to the controlled radio re quires a control frequency of fc (Fig. 3). The ceiver tuning shaft (not shown); shaft |05 is mechanically coupled to adjustable tap I8” of GO push-button 3’ at the oscillator in Fig. ’7 marked with the station desired is depressed. This op Fig. 6; the shaft |01 will adjust the usual volume eration closes the switch identified in Fig. '1 as control device of the controlled radio receiver. 3. One portion of switch 3 closes the ñlament The motor feeder leads will be exactly the same circuit of tube | thus turning on the oscillator. as in Fig. 2. At this point it should be pointed The upper section of switch 3 places condenser c 65 out that time constant circuit 55 is so chosen across the oscillator coil Z. Condenser c is that when the shift is made from the tuning chosen of such capacity as will resonate with control position to the volume control position coil 2 at the frequency fc which is required byA the action of keyer tubes I9 and 2| will be so the circuit of Fig. 2 in order to make it operate retarded that switches 51 and 58, and their re lated circuits, will have had time to complete 70 to tune in the station wanted. The depressing of any one of the station tuning buttons of the their duties before the control motor 25 is put oscillator of Fig. '7 does the same thing as de into action through either tubes i9 or 2| and scribed above, except that each button throws their related keyer circuits. The relays |00 and in its own tuning capacitor which is of correct |0| are fed with supply voltage by leads 200. capacity to tune the oscillator to the frequency, To illustrate the working of the volume con 2,404,101 required by the circuit of Fig. 2 to tune the par-ticular station called for. For volume control it is necessary, as explained before, that the circuit-of Fig. 6 be inserted be tween points P and Q in the circuit of Fig. 2. Depressing volume‘control button 300’ (fv) closes the filament circuit, and puts capacitor o across the oscillator coil 2. Capacitor o is of such ca 10 `ond’voltage of a polarity opposed to said control voltage Vpolarity in response to adjustment of said devices, and utilizing the second voltage to -op pose the effect of the control voltage thereby to terminate said adjustment at a predetermined point. , 3. A method of controlling the position of a volume control device from a remote point, which includes generating oscillations of a se pacity as to provide the oscillator frequency fv (Fig. 3) which, as was explained in connection l0 lected frequency at the remote point, deriving with the volume control circuit, acts on the cir from the oscillations a unidirectional control cuits of Figs. 2 and 6 to cause it to decrease the volume of the radio receiver. Depressing vol ume control button 403’ (fa) turns the oscilla tor on, and connects a, capacitor a across the os cillator coil 2. This capacitor ais of such value that it causes the oscillator to oscillate at a fre quency fa (Fig. 3) which operates, as has been explained, to increase the volume. It will be noted that the oscillator is on for only that pe riod of time required to tune in a desired sta tion, or to set the volume level. Also the only other operation at the oscillator, Kbeside turning it on, is tuning its frequency, and it is not nec essary that the push-bottom method be used. A calibrated continuous tuning would also work at the remote oscillator. In that case a continu ously variable condenser would be used in place of the plurality of fixed condensers. Of course, my invention may 'be carried out by using per meability inductance tuners in place of con densers. The method described by this disclosure might well be used over long distances for co-n trol work, as Well as for short distances. 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 par voltage whose magnitude and polarity7 are de pendent upon the mean amount and sense of fre quency difference between said selected frequen cy and a predetermined reference frequency, ad justing the volume control device to an extent and in a direction determined by said voltage magnitude and polarity respectively, producing a second voltage of a polarity opposed t0 >said control voltage polarity in response to adjust ment of said devices, and utilizing the second voltage to roppose the effect of the control volt age thereby to terminate said adjustment at a predetermined point. 4. A method of controlling the position of a tuning device from a remote point, which in cludes generating oscillations of a selected fre quency at the remote point, transmitting the os cillations to a point adjacent the device, deriv ing directly from the transmitted oscillations a unidirectional control voltage whose magnitude and polarity are dependent respectively upon the mean amount and sense of frequency difference between said selected 'frequency and a predeter mined reference frequency, adjusting the device to an extent and in a direction determined by said voltage magnitude and polarity respective ly, and opposing said control voltage with a bal ancing voltage derived in response to said de that many modiñcations may .be made without 40 vice adjustment to cause said latter adjusting departing from the scope of my invention, as action to cease. set forth in the appended claims. 5. A method of controlling either of the tun ticular organizations shown and described, but What I claim is: ing and volume devices of a receiver from a rc l. A method of controlling the position of a mote point, which includes generating oscilla 45 device from a remote point, which includes gen tions of a selected frequency at the remote point, erating oscillations of a selected frequency at the said frequency being to one side of a predeter remote point, transmitting the oscillations to a mined reference frequency for tuning control and to the opposite side for volume control, transmitted oscillations a unidirectional con transmitting the oscillations to a point adjacent trol voltage whose magnitude and polarity are 50 the device, deriving from the transmitted oscil point adjacent the device, deriving from the dependent respectively upon the mean amount lations a unidirectional control voltage Whose and sense of frequency difference between said magnitude and polarity are dependent respec selected frequency and a predetermined refer tively upon the mean amount and sense of fre ence frequency, adjusting the device to an ex quency difference between said selected frequen tent and in a direction determined by said volt 55 cy and the predetermined reference frequency, age magnitude and polarity respectively, pro and adjusting either of the tuning or volume de ducing a second voltage of a polarity opposed to vices to an extent and in a direction determined said control voltage polarity in response to ad by said voltage magnitude and polarity respec justment of said devices, and utilizing the sec tively. _ ond voltage to oppose the effect of the control 60 6. A method of controlling the position of a voltage thereby to terminate said adjustment at a predetermined point. , 2. A method of controlling the position of a tuning device from a remote point, which in cludes generating oscillations of a selected fre quency at the remote point, transmitting the os cillations to a point adjacent the device, deriving directly from the transmitted oscillations a con trol voltage whose magnitude and polarity are tuning device, which includes generating oscil lations of various selected frequencies, each fre quency corresponding -to a diiferenttuning po sition, deriving from the ‘oscillations a control voltage whose magnitude and polarity are de pendent respectively upon the mean amount and sense of frequency difference between a select ed frequency and a predetermined reference fre quency, the reference frequency being the medi dependent respectively upon the mean amount 70 an of the range of selected frequencies, adjust and sense of frequency departure of said select ed frequency from a predetermined reference frequency, adjusting the device to an extent and in a direction determined by said voltage magni tude and polarity respectively, producing a sec ing the tuning device to an extent and in a direc, tion determined by said voltage magnitude and polarity respectively, producing a balancing volt age in response to said adjustment whose polar 75 ity is opposite to the control voltage polarity and 2,404,101 il opposing the control voltage with the balancing` voltage to nullify the effect of the control volt age. 7. A method of adjusting the adjustable ele ment of a circuit control device of a radio re ceiver from a remote point, Which includes gen erating a control wave of a selected frequency at the remote point, transmitting the wave to the receiver, deriving from the transmitted wave a control voltage whose value is dependent upon the amount of frequency difference between said selected frequency and a `predetermined refer ence frequency, adjusting the adjustable element of said device to an extent determined by said control voltage value and automatically neutral izing the control voltage with a balancing voltage produced during said adjustment. 8. A method of controlling the position of a tuning device from a remote point, which in cludes generating control energy of a selected frequency at the remote point, transmitting the energy to a point adjacent the device, deriving 12 mitting said waves to 'a desired point, deriving from the transmitted waves a direct current volt age whose polarity and magnitude depend re spectively upon the sense and extent of frequenN cy difference between the chosen frequency and an intermediate frequency of said range, control lin-g the adjustment of said volume control in response to said voltage, balancing said direct current voltage against a voltage of opposite po larity to provide a resultant voltage, and ending the adjustment automatically in response to a concurrent gradual decrease of the said resultant voltage produced by a balancing voltage of op posite polarity. 12. A system for controlling the position of a motor-operated radio receiver control device from a remote point, which includes means for generating oscillations of a selected frequency chosen from a range of control frequencies, each of said control frequencies corresponding to a different adjustment of said motor, means for transmitting said oscillations to a point adjacent from the transmitted energy a control voltage the motor, a discriminatcr-rectifier network for amount and sense of frequency difference be tween said selected frequency and a predeter mined reference frequency, utilizing the control voltage for adjusting the device to an extent and in a direction determined by said Voltage magni remote point for generating oscillations of a se lected frequency chosen from a range of control deriving from the transmitted oscillations and whose polarity is dependent upon the direction of frequency departure of said selected frequency 25 at the transmitted frequency a direct current voltage whose polarity and magnitude depend relative to a predetermined reference frequency, respectively upon the sense and extent of fre adjusting the device in a direction determined quency difference between the selected frequen by said voltage polarity and automatically neu cy and the median frequency of said range, tralizing the control voltage with a balancing means energized by the voltage for controlling voltage produced during said adjustment. the adjustment of said motor in response to said 9. A method of controlling the position of a voltage, and further means, responsive to motor receiver control device, which includes generat adjustment, for opposing said direct current ing oscillations of a selected frequency, transmit voltage with a second voltage of opposite polarity ting the oscillations to a desired point, deriving thereby rendering said energized means ineffec from the transmitted oscillations a unidirection tive subsequent to a period of motor adjustment. al control voltage whose magnitude and polarity 13. A control system comprising means at a are dependent respectively upon the mean tude and polarity respectively, and reducing the eiîect of said control voltage sebsequent to the adjustment of said device by a balancing voltage of opposite polarity and equal magnitude. 10. A system for controlling the position of a frequency adjusting device from a remote point, which includes means for selectively generating various oscillations of desired selected frequen cies at the remote point, means for receiving os cillations of one of said frequencies, means for deriving from the received oscillations a control voltage whose magnitude and polarity are de pendent respectively upon the mean amount and sense of frequency difference between said one frequencies each of which corresponds to a dif ferent adjustment of a control device, means for deriving from the oscillations a direct current voltage whose polarity and magnitude depend respectively upon the sense and extent of fre quency difference between the selected frequen cy and the median frequency of said range, means for controlling the adjustment of said control device in response to said voltage and means responsive to said adjustment means for ' balancing the said voltage with a second voltage of opposite polarity thereby to terminate ad justment of the control device. 14. A method of selectively controlling the re spective operation of a tuner device and volume control from a remote point, which includes gen erating a wave of a selected frequency chosen from a range of control frequencies, certain of which frequencies located- on one side of a me quency, motor means energized in response to the control voltage for adjusting the device to an 60 dian frequency correspond to» different adjust ments of said tuner while others of the frequen extent and in a direction determined by said cies located on the other side of said median fre voltage magnitude and polarity respectively, and quency correspond to diiferent adjustments of additional means effective subsequent to a pre said volume control, transmitting said wave to determined adjustment of said device, for 0D posing the control voltage with a balancing volt 65 a desired point, deriving from the transmitted wave a direct current voltage whose polarity and age thereby rendering said adjusting motor magnitude depend respectively upon the sense means inoperative. and extent of frequency difference between the l1. A method of controlling the operation of selected frequency and the said median frequen a volume control from a remote point, which in cy of said range, and selectively controlling the cludes generating waves of a frequency chosen adjustment of said tuner device and volume con from a range of control frequencies, each of frequency and a predetermined reference fre which control frequencies corresponds to a dif ferent desired adjustment of said control, trans trol in response to said voltage. ROBERT E. SCHOCK.