US2245829A

US2245829A - Remote control system

Info

Publication number: US2245829A
Authority: US
Inventors: Stuart W Seeley
Original assignee: RCA Corp
Current assignee: RCA Corp
Priority date: 1937-10-09
Filing date: 1937-10-09
Publication date: 1941-06-17
Anticipated expiration: 1958-06-17
Also published as: US2177843A; FR844399A; GB516648A; CH207810A; GB520141A; US2285684A

Description

June 17, 1941. s. w. SEELEY 2,245,829

REMOTE CONTROL SYSTEM Filed Oct. 9, 1957 2 Sheets-Sheet 1 PDIVFR SUPPL Y INVENTOR STUART W. SEL-LEV zfi 4 BY 716% L. I

ATTORNEY June 17, 1941. s. w. SEELEY REMOTE CONTROL SYSTEM Filed Oct. 9, 1957 2 Sheets-Sheet 2 INVENTOR STU/1R7 W. JZ-ELEV 7K3 205 ER a ATTORNEY I Patented June 17, 1941 REMOTE CONTROL SYSTEM Stuart W. Seeley, Bayside, N. Y., assignor to Rarlio Corporation of America, a corporation of Delaware Application October 9, 1937, Serial No. 1623,1180

3 Claims.

The present invention relates, in a broad sense, to control systems, for operating controllable elements of electrical and other similar apparatus whereby their various functions may be controlled both at the apparatus and from points remote therefrom. More particularly, the invention is applied to a system for operating the tuning means, volume control means, on and oil. controls andother major control elements of 'radio apparatus.

An important feature of the invention is that its objects are obtained without expenditure of powerduring non-operating or standby periods and without the necessity of any wiring outside of that already existing in buildings provided with a commercial power supply network such as is found in all buildings provided with the usual house lighting system or the like.

Briefly, the arrangement which, is described herein for the purpose of illustrating the features of the invention, makes use of a single motor at the receiver for operating both the tuning instrumentality of a radio receiver, as, for instance, a multiple unit condenser arrangement, and the volume control device which may be a potentiometer. At the receiver there are provided a series of selector buttons and related circuits for conditioning the motor circuit. A plurality of settable cam devices arranged to rotate in unison with the tuning shaft of the receiver, provide a control for themotor circuit to determine its direction of rotation and the extent of its operation. The receiver is turned on by means. of an electrical switch which also is used to control the motor for the purpose of operating the volume control device- In addition to the above, the invention provides a remote control arrangement through the operation of which all of the functions necessary to necessary to a clear understanding of the invenvtion;

Figure 2 illustrates diagrammatically the wiring diagram of one of the remote control boxes; and,

.sary energizing potentials from Figure 3 is a front view of the panel of a remote control box.

The nature of the method of remote control the necessary functions for operating the receiver may be performed electricaliy'from a remote point by means of push-buttons or switches located at the remote point. An important feature of the invention is that various carrier frequencies and arrangements of their cycle modulating envelopes (if the network supplies 60 cycle current) are transmitted through the power line to act on relays which are used to make or break connections between a motor which may be geared to the condenser shaft or to the volume control shaft and the A. C. network.

In an embodiment of the invention, the remote control unit contains two oscillators, the frequency of each being made, for instance, either 200 or 300 k. c. Means are provided for reversing the phase of the 60 cycle line voltage which acts as the plate supply for the oscillator tubesso that the system is capable of feeding into the power line either or both of two frequencies with two possible phase relations of the 60 cycle modulating envelope. The result is an intermittent series of pulses of carrier frequency modulated at 60 cycles with the interval of each pulse not greater than ,4 of a second. This follows from the fact that each tube will oscillateonly when the A. 0. plate voltage applied to it is positive with respect to the tube's cathode. Two carrier frequencies and two phases of the modulating voltage result in 10 possible combinations of frequency and phase and the selective circuits in the receiver unit operate to energize any one or pair of four low current relays which in turn cause 60 cycle power to be supplied to'themotor to thereby cause it to operate either the multiple unit condenser or the volume control potentiometer.

Figure 2 of the drawings shows the oscillator connections. The tubes230 and 23! together with their associated circuits form the two oscillators. Tubes 230 and 23! derive their necesthe available A. C. network by connection of polarized plug 243 to a suitable outlet of the network. Actually plug 243 is plugged into the outlet and the tuming on and off of the power supply is accomplished by means of switch Sw located on the control box. When switch Sw is in the on" is A. C. plate voltage plate current to position the line voltage is applied across the primary of transformer 238. Transformer 238 is provided with two secondaries. One of these comprises a heater winding 245 which furnishes current of proper voltage to the heater connections H, H of the two tubes. The other 'secondary comprising a winding 246 supplies the two tubes 230 and 23l with plate voltage through the circuits including switches operated by push buttons 200-208 inclusive. The midpoint of winding 246 is'grounded to give the effect of a pushpull circuitjor reasons which will appear hereinafter.

The upper portion of Figure 1 of the drawings shows the selective circuits in the receiver unit. A cold cathode gas tube 6 the operation of which is explained in my United States Patent No. 2,177,843 issued October 31, 1939, is coupled to the power line through conductors 2, 3 and polarized plug-in device I. Tube 24 which may be of the GR? type, plays a double role in the arrangement shown in that its diodes produce nonfiltered full wave rectification of a small 60 cycle voltage which, as will be described hereinafter, is used as a. bias to maintain

tubes

24 and 23 at cut-01f in the absence of carrier current signals. The 'triode plate circuit of tube 24 conof the oscillators which results in optional frequency and modulating phase relations in the carrier voltage emanating from the control oscillator as will be described hereinafter. The necessity for two oscillators in the control unit.is

apparent when it is realized that it is often necessary to close more than one relay at

Relays

8 and 36, for instance, are energized when both oscillators are operating at 300 k. c. with opposite polarities of A. C. line voltage. Relays 3 and 3'! become energized when one oscillator is at 300 k. c. and the other at 200 k. c. with opposite line voltage polarities for plate supply.

The motor unit energized bythe energization of the contacts of any of the four

relays

8, 36, 31 and 38 in the receiver may, for example, consist of a 23 volt capacitor type A. 0. motor 92 which may be geared to the condenser shaft I09 or to tains a relay 36. This relay closes switch Sac when suflicient carrier voltage appears across the circuit l5, I! which is tuned to 300 k. c. Resonant circuit l5, I1 is connected between the control grid of tube 24 and ground. It should be noted that the peak value of the incoming 60 cycle modulated carrier must coincide in time with the positive peak of the 60 cycle plate volt-- age supplied to tube 24 in order for current to pass through the relay 36.

Tube 23 which is. shown as a 6N7 type tube is connected as a push-pull phase detector with the rectified envelope of the modulated 200 k. 0. carrier applied, to its grids in parallel. The insertion of tube 20 which may be a 61-16 type rectifier tube is for the purpose of deriving suiflcient grid excitation for tube 23. It should be understood that if a double triode tube with lower amplification factor were available in place of a 6N7 it would obviate the necessity of tube 23 and the modulated carrier frequency could be applied directly as is done to tube 24. Carrier energy of 200 k. c. applied to the line with a given polarity of 60 cycle modulating voltage energizes and closes one of the

relays

31, 38 in the plate circuit of tube 23. Reversal of the line voltage applied to the oscillator plates causes the other relay of tube 23 to close.

A survey of the combined operation of the control and receiver units will show that 300 k. c. modulated by 60 cycles in, let us say, for convenience, phase A, causes the gas tube 6 to conduct which energizes relay 8, thus throwing S3 to the right. A change of oscillator frequency to 200 k. c. with no change in the phase of the modulating line voltage cause's plate current to flow in the upper half of tube 23 and as a consequence relay 33 is energized which throws switch 833 to the right. Reversal of the phase of the applied to the oscillator causes flow in the lower half of tube 23 and relay 31 becomes energized throwing switch $31 to the right. If the frequency is then changed back to 300 k. c. relay 33 is energized throwing $30 to the right. It is to be understood that the function of the mash-button switches on the control unit is to apply the line-voltage the shaft of the volume control potentiometer I02 through suitable gear trains 95, I03 and 93, lfll respectively. The motor circuit is provided with an arrangement comprising a tapped reactor 81 and condenser 9| for changing the phase angle of the current supplied to the motor so that the motor" is capable of running in either direction. Operation of the motor 92 at 18- volts as when it is energized through resistors RI or R2, causes the motor to run in a position where gears 93 and llll are engaged, thereby operating the volume control shaft. Increasing the voltage to 23 volts, causes the motor to speed up and its armature is thereby thrust axially in the direction indicated by the arrow so as to disengage pinion 93 from the volume control gear ill! and engage the pinion gear 95, condenser shaft gear I08. A more detailed explanation of the manner in which the motor shaft operates may be found in U. S. patent to Hopkins 1,999,359, issued April 30, 1937.

A series of cams and contactors control the proper direction of rotation and also the stopping and starting of the motor for the selection of a desired station. In the drawings, for convenience only four cams, H0 through 3 have been shown, however, it should be understood that any number of cams may be utilized depending upon the number of stations desired to be tuned to automatically. The cams ,may be preadjusted on the shaft I69 to positions which correspond to the stations desired for each of the cams. The manner in which the cams control the operation of to or to shunt condensers across, either or both 76 the motor and their adjustment is fully described in U. S. patent to-Garrett 1,956,419,.issued April 24, 1934. 4

Turning the receiver "on" and o is eilected by means of the relays but it is not necessary to maintain the supply of carrier current continuously in order to have the receiver operate continuously once it is turned on. This follows from the fact that when relay 3 closes it causes a small locking relay to close the line circui. to the primary of the receiver power transformer connected across

terminals

19 and 80.

It is thought that the invention will be best understood by taking up at this time the operation of the push-button tuning arrangement, the "on and "o mechanism and the volume control mechanism as operated by means of switches. etc., at the receiver without regard to the remote control featureof the invention. To turn the receiver "on it is first necessary to insert polarized plug I into a suitable outlet of the power supply network. After this is done switch 33 is turned counter-clockwise thus causing contcctor 34 to come in contact with contact point 39 and a time.

. The motor thereby rotates shaft also switch 63, 62 to close. Closure of

switch

63, 62 connects the two contact strips 41 and 48 together, electrically, through

wires

65 and 66 with the result .that voltage is put on transformer windings 44 and 15, and across

terminals

19, 80. The latter energizes the receiver through the usual power transformer. Magnet 13 is also energized by connection of its winding across secondary 16. The circuit may be traced as follows:

From the left hand side of trans ormer secondary winding 16 through wire 10, ire 14, relaywinding 13 wire 55,

switch

56, 51 which is normally closed when the receiver is not in, operation, switch 59 (now closed due to the counterclockwise operation of lever 83), conductor BI,

conductor 69, back to the right hand side of winding 16. When the relay winding 13 becomes energized, it pulls arm 52 to the right as shown in full lines in the drawings thus closing

switch

49, 50 which acts to connect electrically the contact bars 41 and 48. When this happens

switch

56, 51 is opened due to the fact that the arm 52 is flipped over to the right with the result that the relay winding 13 becomes de-energized. However, spring 53 keeps the arm 52 in the position shown in spite of the de-energization of the magnet 13. It should be understood that elements 63 and 64 are spring contact members which act to maintain switch arm 83 in a neutral position in the absence of force tending to 1 to the left hand side of 18.

rotate it either clockwise or counter-clockwise.

To tune in a station after the set is on and the tubes properly operating, one of the buttons I through I29 depending upon which of the stations represented is desired, is pressed down and held down. For example, if it is desired to receive the station corresponding to push-button I26, thus, causing the contactor I26 to come in contact with the conductor bar I30. This completes the circuit of motor 92 across winding 16, thereby causing current to flow through the following circuit:

From the'right hand side of transformer secondary winding 16, wire 69 to ground strip I30, contactor I26, conductor I20, switch II6 which happens to be contacting its lower terminal due to the fact that the cam follower is riding on the high portion of cam II2, conductor I18, motor 92, conductor 14, conductor 10 to the left hand side of the transformer winding 16. In this way the full voltage across the transformer winding 16 is applied to'the motor 92, thereby causing its armature to be thrust in the .direction indicated by the arrow which results in pinion gear 95, meshing with gear wheel I08. I09 and, hence, the rotors of the multiple-unit, condenser I00 as well as the cam shaft I09. Due to the fact that the motor shaft 94 was thrust in the direction indicated by the arrow the right hand end of the shaft forces the contactor arm to the right against the action of spring 91, thereby short circuiting contactors and 30'. The

contactors

30 and 30 are suitably connected to the receiver and act to remove the output from the loudspeaker so that the receiving set is quieted during the tuning operation. It can be seen, from the above that the motor 92 is caused to rotate in one direction carrying with it the rotors of the multi-unit condenser I00 as well as the set of, cams represented by cams IIO through H3. When cam H2 which corresponds to the pushvbutton I26 is rotated to a position which causes the switch II6 to open, that is, to a position 7 that button is pressed down and held down,

I To turn the volume up where both the upper terminal and the lower terminal thereof are open (see position of switch II1) the motor circuit is broken stopping motor 92 and hence rotation of shaft I09. When this happens it is no longer necessary to hold down push button I26 so that the button may now be released. If instead of the station tuned to another station had been desired, let us say the station corresponding to push button I25, then I25 would be depressed and held down, thus causing the motor circuit to become energized through the following electrical path:

From right hand side of transformer winding 16, conductor 69, bar I30, contact device I25 (now in contact with I30 due to depression of button I25), conductor II9, switch II5 which, as shown, contacts its upper terminal owing to the fact that the cam follower is riding on the lower portion of the cam III, conductor I11, through motor 92, conductor 14, conductor 10, the transformer winding This rotates the motor 92 in the opposite direction from that previously described in connection with the depressions of push button I26. The circuit is broken and the motor stops when cam III breaks contact at switch I I5.

After a station is tuned to and signals are received, it may be necessary or desirable to vary the volume either up or down for proper enjoyment of the signals. For this purpose, the switch 83 is used: Operation of this switch counterclockwise causes the motor 92 to increase the volume and clockwise to decrease the volume. switch 83 as previously stated is turned counter-clockwise, thereby closing switch 59, 64. This energizes the motor 92 through the following circuit:

Left hand side of the transformer winding 16, conductor 10, conductor 14, motor 92, conductor I11,-resistor R1, conductor 68, switch 59, 64 (now closed), conductor 6I and conductor 69 to the right hand side of transformer winding 16. Re-

sistance Ri-acts to reduce the voltage applied to the motor 92 with the result that gear 93 stays in engagement with gear IOI as shown. This is for the reason that the thrust on the motor armature due to the reduced voltage is not sufficient to shift the motor shaft 94 as described in connection with the tuning operation.

, Rotation of the motor will adjust movable arm I03 of the volume control potentiometer I03, I04, through shaft I02, so as to increase the volume. As soon as the desired volume is reached the switch 63 is allowed to return to its normal middle position which is the position shown in the V drawings, thus breaking the contact 59, 64 which stops the motor 92. If it is desired to reduce the volume the switch 83 is turned clockwise, thus permitting spring contact 64' to come in contact with'connector 60. The motor is energized and rotates in the opposite direction than in the previous example. The motor is energized through the following path: 7

From left hand side of transformer winding 16, conductor 10, conductor 14, motor 92, con ductor I18, resistor R2, conductor 61,.switch 60, 64 (now closed), conductor 6|, and conductor 69 to the right hand side of transformer winding 16. As in the case of resistor R1, resistor R2 also reduces the voltage applied to the motor with the result that the gear 93 stays in mesh with gear wheel IOI. However, the motor 92 will rotate in the opposite direction and rotate the movable arm I03 oppositely to the previously described volume control operation, thereby reducing the volume. When the desired volume is reached switch 83 is allowed to return to its normal released position, thus breaking the motor circuit. To turn the receiver off, button I18 is depressedwhich closes switch I80. This energizes the winding of electromagnet 12 through the following circuit:

From the left hand side of transformer winding 16, wire 10, relay winding 12, wire 1|, switch I80, wire I8I, wire 6i and wire 68, back to the right hand side of transformer winding 16. Energization of relay 12, flips thearm 52 counter-clockwise, thus opening

switch

48, 50 and thereby disconnecting contact bars 41 and 48 which de-energizes the receiver. At the same time, the

switch

56 and 51 is closed.

The remote control box shown in Figure 2 energizes circuits and tubes capable of generating oscillations of two predetermined frequencies with 60 cycle A. C. voltage employed directly as plate supply through transformer 238. The

'function of the switches operated by pushbuttons 200-208 is to connect circuits to the oscillator tubes 230 and 23I which apply plate potential to either or both tubes to energize the same and to shunt condensers across either or both of the oscillators to thereby alter the oscillating frequency and also to alter the phase of plug I.

control circuits in the receiver through polarized Tube 6 is arranged by means of its con- 'nection to the polarizing potential divider 4,

the 60 cycle A. C. plate voltage to give various combinations of output frequency and modulating phase to the controlling energy fed into the power line.

To operate the receiver from a remote point, the polarized plug 243 is plugged into a suitable outlet of the A. C. network and the switchSw closed. This immediately applies the line voltage across the primary of the transformer 238 thus energizing the heater circuits of tubes 230 and 23I through heater winding 245 and placing a voltage across secondary 246. It should be noted that the mid-point of secondary 246 is tied to the common cathode connection between tubes 230', 23I. In Fig. 2 push-button 200 which closes switch 260 is both the on button and the volume up button. Push button 208 which when depressed closes switches 221, 228,and 228 and switches 226 from its upper contact position-to its lower contact position is the "off button. The volume down push button 204 closes switch 2I5. The six station

selector push buttons

20I, 202, 203, 205, 206 and 201 are arranged to close variousswitches which will be described below in greater detail.

The operation of the device is as follows:

To turn the set on" push button 200 is depressed closing switch 280 thereby connecting the top side of secondary winding 246 to the tap 236' on coil- 238. By-this means a 60 cycle A. C. voltage is applied as plate supply for tube 230. This will cause the tube to oscillate at a frequency determined by the

resonant circuit

236, 231 which in this case is 300 k. 0. Application of the 60 cycle voltage permits tube 230 to oscillate only during that portion of a 60 cycle period during which the plate-of the tube is positive with respect to its cathode. The output of tube 230 is coupled into the A. C. power line through the connection including coil 238 and condenser 242. The energy thus fedinto the line consists of a voltage at 300 k. c. modulated at 60 cycles.

thus it appears as a series of pulses each of which is not more than $6 of a second in duration. This energy is transmitted to the receiver Fig.

1 through the A.C. power line and enters the 75 which appears and by proper connections through polarized plug I to the A. C. line, so that an incremental voltage developed across coil I0 by resonant rise in series resonant circuit 8, I0 tuned to 300 k. c. is all that is required to initiate a discharge between the auxiliary electrodes AU; and AUz. As a result of this discharge the gap between AU2 and A is ionized and relay 8 is energized. For this to happen it must be understood that the peak of the modulating envelope of the voltage across I0 must coincide substantially in timerelation with the peak 60 cycle present across the condenser so that the net difference of potential between AUi and AU: is increased (see my copending application previously referred to). Energization of relay 8 causes switch Ss to be thrown to .the right thereby breaking contacts I41, I52 and making contacts I52, I48 and I50, l5l. Connection of I50 to I5I connects together contact bars 41 and 48 by means of wires 8I, 82.

When this happens A. C. voltage is applied to the primary of the receiver power supply transformer through terminals 19 and as well 'as the winding 15, the latter being through conductors 11 and 46. Voltage is thus developed across secondary winding 16 and causes relay winding 13 to be energized thereby pulling arm 5| over to the right as shown closing

switch

48, 50 which shorts the bars 41 and 48. At the

same time switch

56, 51 is opened to thereby remove voltage from coil 13 and prevent its becoming over heated, while the receiver is on. Relay 13 is energized through the following circuit:

Left side of 16, wire 10, wire 14, coil 13, wire 55,

switch

56, 51, wire 58, wire 68, contacts I3I, I60 of Sac, wire I6l, contacts I31, I51 of Sn, wire I63, contacts I43, I54 of S38, wire I65, contacts I48, I52 of S8 (bearing in mind that $8 is over to the right), wire I15, wire 69 to right side of 16 which completes the circuit.

Now that the receiver is on it will be shown how to select a particular station: To tune to a station as, for instance, to the station corresponding to button 20I (Fig. 2) this button is pressed down, thus closing switches 208 and 2"). Closure of 2I0 connects the plate supply voltage to tube 230 as follows;

Upper terminal'of 246 through wire 248, wire 252, switch 2I0, wire 25l, wire 280 to the tap on coil 236. That causes tube 230 to oscillate at a frequency determined by 236, 231 (say 300 k. c.) witha certain phase of the 60 cycle modulatin -envelope. Since 208 is also closed by depressing button 20I, oscillator tube 23I-is also supplied with A. 0. plate voltage by a connection from the bottom half of winding 246, conductor 250 closed switch 226 conductor 26i switch 208 (which is ciosed due to the depression of button 20I), conductor 226, conductor 253 to tap 235' on coil 235 and oscillates at a frequency determined by 235 and 234 (300 k. c.). The oscillations in tube 2:" appear only during those portions of the A. C. 60 cycle current when'the plate of either

tube

230 or 23! is positive with respect to its cathode.

Since plate voltage available for application to tube 230 is out of phase with that available to tube 23,1 because of phase relation between opposite ends of transformer secondary 246, it follows that the envelope of the output voltage in the output of tube 230 is out of phase with the envelope of the output of tube 23L These two oscillations are fed into the power line or network and taken out at the receiver where they appear across line 2, 3. This will cause tube 6 to pass current as previously described, thus energizing relay 8 (due to the output of oscillator 230) andthrowing switch S8 to the right. At the same time switch S36 is thrown to the right due to energization of relay 36 which is caused by the energy from the output of tube 23I acting on tube 24. This action results from the following:

60 cycle voltage is applied between the plate of tube 24 and its cathode from the lower side of transformer secondary 42, the primary 44 of which is connected across the line 2, 3. The phase arrangement is such that modulated (300 k. c.) carrier which appears across coil I due to resonant rise in circuit I5, I! and coupled to coil I3 causes tube 24 to pass current in its plate circuit when the peak value of the modulation envelope impressed on the grid of tube 24 coincides in time with the peak value of the 60 cycle A. C. voltage applied to the plate thereof. The diode portion of tube 24-acts merely to produce an unfiltered full wave rectified 60 cycle voltage derived from secondary 35.

A portion of this, namely, the drop across resistors 3| and 32 is applied between the grid and cathode of tube 24 to maintain the tube in a cut-off I condition until a modulated voltage, whose envelope is in the proper phase relation to the A. C. plate voltage, appears across the tuned circuit I5, I1. Voltage of this required phase will appear due to the output of oscillator tube 23I. It can be seen that output voltage which energizes tube 6 will not cause the passage of plate current through tube 24. Throwing of S36 and S8 to the right by the action described previously, will cause the receiver to be tuned to a predetermined station which is the same as the station corresponding to button I24 when the receiver is opera-ted locally. The circuit which energizes the motor in this instance may be traced as follows:

From the right side of secondary winding 16 through wire 69, wire I15, through contacts I52, I48 of switch S8, wire I65, contacts I54, I43 of S38, wire I63, through contacts I51, I3Iof S37, wire I6I, contacts I60, I32 of S36, wire I61, wire II8, cam switch I'I4, lower contact of switch 4, wire I18, motor 92, wire 14 and. wire to the left side of winding 16.

The full voltage across I5 is thus placed across the motor which causes motor shaft 94 to be thrust axially in the direction indicated by the arrow thus causing the engagement of gears 95 and I00 thereby rotating the rotor of multiple unit condenser I00 and also cam shaft I09. The motor, continues to rotate until its circuit is broken due to the fact that it comes to a position where switch H4 is not in contact with either its upper or lower terminals.

It should be noted that the axial thrust of the motor shaft when running on full voltage causes spring contactor 99 to engage or

short contacts

30 and 30 to thereby remove the output voltage from the loudspeaker or otherwise quiet the receiver. As soon as the circuit is broken by switch II4 the motor stops and the armature slides back to its original position as shown in the drawing, thereby allowing spring 91 to draw back spring contact 99 and thereby remove the short-circuit from terminals 30, 30'.

Referring again to Figure 2, if a station correhad been desired, depressed closing when switch 209 was closed in the previous illustration to 200 k. c. This is caused by the connection of condenser 233 across a portion of

tank circuit

234, 235. This connection is brought about by means of switch 2|! in the following manner. v

Starting at the cathode terminal on coil 235, through wire 253, wire 226, switch 2I6, switch 2", wire 263, wire 255, through condenser 233 to plate of 23 I.

As the result of pressing down push button 205 there are two voltages impressed upon the A. 0. power line. One, has a frequency of 300 k. c. and is modulated in, say, phase A, which will cause tube 6 to pass current thus energizing relay 8 and causing switch S8 to be thrown over to the right. The other 200 k. c. modulated in phase B will be shown to cause plate current to flow in one of the plate circuits of tube 23 thereby energizing relay 31 causing S37 to be thrown to the right.

The circuit comprising tube 23 and its associated elements acts in the same manner essentially, as tube 24 in that it operates as a selective phase detector. The section of the tube in which plate current flows is determined by the phase of the modulated 200 k. c. impressed upon the parallel grids of the double triode tube 23 with respect to the phase of the A. 0. plate voltage obtained from the push-pull transformer secondary 42.

Unfiltered full wave rectified bias voltage is applied to the grids of tube 23. This bias voltage is developed across the resistor 3| and acts to maintain tube 23 inoperative in the absence of'A. C. grid voltage. It may be noted that tube 20 is not inherently a part of the system. It acts merely to increase effectively the sensitivity of tube 23 in the following manner.

The modulated 200 k. c. voltage impressed across the plate cathode terminals of diode detector 20 is rectified and appears across resistor I9 as a low frequency product of demodulation whose wave shape is the same as the modulation envelope of the incoming 200 k. c. This expedient was found necessary in an actual embodiment of the invention because the amplification factor of tube 23 was not sufficiently low to permit obtaining the desired sensitivity. A tube such as 23 but with the lower amplification factor would eliminate the necessity of tube 20.

The phase of the envelope which appears between the grids of tube 23 and the cathode as the result of depressing button 205 on the remote control unit (Fig. 2) causes plate current to flow in the lower half of tube 23-due to the fact that the potential on the lower half of transformer secondary 42 is arranged to be positive when'the grids are positive.

Relays 31 and 8 having been energized and subsequently having thrown to the right their associated switches S37 and S8, cause a new station to be tuned. The motor 92 is energized through the following circuit:

This means that the contacts of switch I31 are open.

I to be energized and ,of the push buttons 201 'isto alter the Right hand side of winding 16, wire 69, wire I15, contacts I52 and I48 of S8, wire I65, contacts I54, I43 of Sac, wire I63, contacts I51, I38 of S31, wire I10, wire I2I to cam switch III.

It will be noted that both the upper and lower This signifies that the tuning condensers when last operated were set to the same station as is now desired.

Consequently, the motor will not operate.

Actually, however, under these conditions signals from the desired station would have come in upon depression of the on button 200 after the usual time required to heatthe tube cathodes of the receiver.

If instead button 202 is depressed, switches 2H and 2I2 are closed. They cause oscillator 230 to feed into the power line carrier frequency of 200 k. c. modulated at 60 cycles in a phase which would cause tube 6 to operate if the frequency had not been changed from 300 k. c. to 200 k. c. This energy will be stepped upby resonant circuit I4, I6 (Fig. 1) and will cause the modulation envelope to appear on the grids oftube 23. The phase of the plate voltage on the top section of tube'23 is so arranged that current passes through relay 36 energizing it, causing $38 to be thrown to the right. The-action which takes place is the same as though button I25 had been pressed'locally and the receiver will tune to a station corresponding to the setting of 6am III on shaft I09.

It should now be apparent that the function 20I,- 202, 203, 205, 206 and output frequency and the modulatingphase of the voltage developed in the oscillation generating circuits comprising tubes 230, 23I and their associated circuits.

The resultant voltages act upon different combinations of tubes shown in Figure. 1 and cause energlzation of several possible combinations of relays which in turn cause to be connected electrically from a remote point, the samecontacts which would be made by local operation of the receiver through the push-buttons I24 through ,I29 inclusive of Figure 1.

Assuming that the receiver has been turned fon and is/tuned to a desired station, the operation which enables one to vary the volume from a remote point will now be taken up.

Ifit is desired to increase the volume, button 200 is depressed. This performs the same function electrically as when the receiver is .tumed on. by means words, switch 260 is closed supplying oscillator tube 230 with plate potential. generates carrier frequency of 30.0 k. c. modulated with 60 cycle plate voltage as previously described. The generated energy is transmitted over the A. C. power lines, and is picked up in the receiver circuits of Figure 1, causing tube 6 to ignited and relay 6 to beenergiz'ed thus throwing switch St to the .right. The motor circuit is thereby energized causing the motor 92 to run at reduced speed whereby ume control potentiometer is effected in the following manner:

' Current flows 69, wire I15, contacts I52, I46 of Sn, wire I65, contacts I54, I43 of Sara, wire 163; contacts I51, I31 01' S37, wire IBI, contacts I60, I31 of S36, wire 66, resistor RI, wire I11, motor 92, wire 14, wire 16 to leit side of 16.

The voltage drop across resistor RI causes the motor to run at reduced speed (below the speed at which it runs to eflect tuning). Consequently,

of depressing button 200, in other I of A. C. voltage supplied as plate-supply.

- remains engaged to volume there is ins'ufilcient' axial thrust of shaft 94 to cause axial differences and the motor gear 93 control gear I0l. motor causes shaft I02 to rotate the movable arm I03 of the poresistance I04. Wires I05, I06,

Rotation of the thereby moving tentiometer along I01 may be connected to the audio system in the receiver in such a. way that variations of the position of arm I03 on element I04 cause variations in the volume output of the receiver.

It should be noted that current cannot flow through relay 13 because

switch

56, 51 is open due to the fact that arm 52 was previously flipped over to the right when the set was turned on by depressing button 200 the first time.

If it is desired to run the volume down then button 204 is depressed, closing switch 2I5 and thereby energizing oscillator 23I which emits a frequency of 300 k. c. modulated by a 60 cycle voltage in the opposite phase to that used to modulate 230 in the preceding illustration of increasing the volume.

' does not operate because 30' ation of the motor 92 isas The 300 k. 0. energy is transmitted over the power lines and is picked up by the receiving units. Due to the phase relation of the 60 cycle voltage on the plate of tube 24 (Fig. 1) tube 24 is caused to pass current in its plate circuit energizing relay 36. It is to be noted that tube 6 the phase of the modulation envelope is not correct to initiate a discharge in this tube. switch S36 is thrown to the right. Motor 92 now runs at reduced speed in a direction opposite to that in which it runs to increase the volume. The electrical circuit which controls this operfollows: L

Right side ofwinding 16, wire 69, wire I15, contacts'I52, I41 of 88, wire I66, contactsi53, I45 Of- Sst, wire I64, contacts I55, I of Serf wire 16:, contacts 958, I36 of S36, wire 61, resistor m, wire I18; motor-.92, wire 14, wire In to left side of winding 16.

The action is the same as that which causes the volur'iije to be increased except that the motor -nowrunsinreverse direction, .thus causing arm 226 from its left hand position shown to its right the setting of thevolbe so 23I tooperate at .200 k. c. and

hand position and at the same

time closing switches

221, 228 and 229. When this happens the electrical action is such as'to cause oscillator normal phase Oscil- 230 to operate at 300 k. c. wlththe lator 230 is now made to run'at-300 k. 0. due to the energization thereof 1 thru the following circuit:

From top of winding 246 conductor 249 closed switch (226 (switch in its right-hand position) closedswitch 221 conductor 25I, conductor 266 to tap 236' on the coil 236. The circuit is completed thru ground since the, center tap of secondary 246 is connected to ground and the cathode of the tube 230 is connected to ground. The depression of button 206 causes oscillator. tube also causes the plate supply voltage to be in phase with the plate supply voltage on the oscillator 230. This is obtained thru the following circuit:

Starting at the topof winding 246 249 closed switch 226, closed switch 226 wire 253 tap 236' on the coil 235 back thru'ground between the cathode of the tube 23I' and the grounded center pointof winding 246.

7 change the frequency the condenser v233 is Relay 36 being energized,

conductor shunted across part of the coil 235 thru the following circuit:

From the plate of tube 23I to the tap 235' on coil 235 wire 253 closed switch 228 closed switch 229 conductor 254 conductor 255 to the righthand side of the condenser 233, it being noted that the left-hand side of the condenser 233 is connected to the plate of the tube 23I. Hence the condenser 233 is shunted across that part of the coil 235 which is between the plate of the tube 23I and the point 235'. Oscillator 23I runs at 200 k. 0. but the phase of its modulating plate supply voltage is reversed from that of any previous condition explained and is now in phase with the A. 0. Voltage applied to oscillator 230. In other words, the A. C. voltage used as power supply for both tubes is now taken off the top half of transformer secondary 246 through the medium of the switches which are closed when button 208 is depressed.

Accordingly, there is impressed on the A. C. power line as a transmitting medium two frequencies, 200 k. c. and 300 k. c., both effectively contained in the same envelope. These frequencies are picked up by the receiver selective circuits as previously described and they act on tube 6 and tube 23. Tube 6 is ignited and causes relay 8 to be energized in the manner disclosed in the discussion pertaining to turning the receiver on and increasing the volume level. The

upper half of tube 23 has the proper polarity of A. C. voltage applied to its plate to cause plate current to pass throug relay 38 when 200 k. c. modulated in the phast resulting from the action of pressing 208 in Fig re 2 isapplied. Consequently, relays 8 and 3 are energized throwing SWitChES'Si'I and $38 to the right. This causes magnet coil 12 to be energized, throwing switch to theleft, breaking

contact

49, 50 which removes the A. C. supply from the primary winding of the receiver power supply transformer shutting the receiver off. It is to be noted that when the arm of switch 5! is thrown to the left,

switch

51, 56 closes, thereby making the device ready for the next turn on operation. The

circuit which performs this function is as follows:

From the right side of 16, wire 69, wire I15, contacts I52, I49 of S8, wire I65, contacts I54, I44 of S38, wire II, coil 12, wire I0 to left side of winding 16.

If the station corresponding to button 206 is desired, this button is depressed, closing switches 2I8, 222 and 223. This will cause oscillator 230 to operate at 200 k. c. and oscillator 23I ate at 300 k. c. with A, C. modulating voltages which are mutually out of phase. The resultant output energy transmitted through .the power line acts upon the following circuits in the receiver:

The 200 k. 0. energy is picked up by coil I4 and is ultimately placed upon the grid of tube 23. This in conjunction with the fact that the plate voltage on the top section of 23 presents its peak value when the envelope of the carrier on the grid of 23 becomes positive, causes plate current to flow through the relay winding 38 causing $38 to be thrown to the right. At the same time the 300 k. c. component of energy acts on the grid of tube 24 whose plate voltage is properly phased to cause current to flow through relay winding 36 energizing it and throwing S36 to the right. The closure of these switches causes voltage to be applied to the motor 92 through the medium of a cam switch (not shown) which acts in a to opersimilar manner as cam switches H4 through '1, causing the motor to rotate until the cam comes in the position to break the cam switch, as described hereinbefore.

To tune to a station corresponding to button 201, this button is depressed, closing switches 2I9, 220, 224, 225. That causes both 230 and 23I to operate at 200 k. c. with the phase of the modulating voltage mutually opposite. The resultant energy acts on the grid of tube 23, both halves of which now pass plate current energizing

relays

37 and 38, throwing switches S37 and 8:8 to the right. This brings about a rotation of motor 92 through the medium of still another cam switch, not shown in the diagram, but similar in action of those. shown. The operation is as previously described.

In the description of the various operations of the invention given above, it should be borne in mind that when tuning to a station by depressing any one of the station selector buttons I24 through I29 of Figure 1, or any one of the

station selector buttons

20I, 202, 203, 205, 206 and 201 of Figure 2, the selected button must be kept depressed until its corresponding cam controlled switch breaks the motor circuit at which time the push button may be released so as to allow it to return to its normal position. The same is true of the

volume control buttons

200 and 204, so that if it is desired to change the volume either button 200 or button 204 is depressed and kept depressed until the motor 92 has operated the potentiometer sufficiently to give the desired volume at which time the depressed button is released. To control the volume locally the lever 85 of Figure 1 is turned clockwise or counterclockwise depending upon which direction the change is desired and maintained in the new position until the desired volume is reached. When the desired volume is reached the lever 83 is released, thereby allowing it to return to its normal position through the action of the spring contacts 63 and 64. On the other hand, for turning the receiver on locally it is only necessary to rotate the lever 83 counter-clockwise and immediately releasing the same. At the remote point, all that is necessary to turn the receiver on is to momentarily depress push button 200 while turning it oif which required only the momentary depressing of the push button 208.

It will be evident to those skilled in the art that in some instances as in some apartment houses conditions might prevail where the control energy impressed upon the network of one' apartment would find its way to the network of another thereby" controlling a radio receiver in the second apartment. To prevent this, it is only necessary to isolate the controlling energy in any particular apartment by connecting to the line at the meter board a series choke coil of suitable dimensions for the frequencies in question. Such an arrangement would prevent the control energy from being transmitted beyond the meter to another apartment network. It would also tend to act the other way, that is, it would prevent control frequencies from some other network entering the first network. It should be understood that while the invention has been described in connection with a radio receiver, it is not limited thereto since it is quite obvious that it may be applied to other apparatus having one or more control shafts 4 adapted to be remotely controlled.

I claim: 1. In a remote control system, a transformer having a primary winding adapted to be connected to an alternating current distribution network and a secondary winding, a first electronic tube oscillator including an anode, a cathode and a grid, a tank circuit for said tube connected between the anode and cathode of the tube, a second electronic tube oscillator having an anode, a cathode and a grid, a tank circuit for said second tube connected between the anode and cathode of said second tube, a connection between the grid electrode of the first tube and a point of the first named tank circuit, means for connecting the grid electrode of the second tube to a point of the second named tank circuit, means connecting an intermediate point of said secondary winding to both of said cathodes, means adapted to be connected to said first named tank circuit for altering the frequency characteristics thereof, means adapted to be connected to said second named tank circult for altering the frequency characteristics of the second tank circuit, a plurality of selectively operable means, one of said means acting upon operation to connect a point of said first named tank circuit to one end of said secondary winding, another ofsaid operable means acting upon operation to connect said first named tank circuit to said first named end of the secondary winding and simultaneously to connect a point of the second named tank circuit to the other end of said secondary winding, a third one of said operable devices acting upon operation to connect apoint of said first named tank circuit to said first named end of the secondary winding and simultaneously to connect the first named frequency changing means to the first named tank circuit, a fourth one of said operable means acting upon operation to connect a point of the second named tank circuit to said second named end of the secondary winding and simultaneously to connect the second named fre quency changing device to said second named tank circuit, a fifth oneof said-operable means second named tank circuit to said second named end of the secondary windinga sixth one of said operable means, acting upon operation to connect a point of the second namedtank circuit to the second named end of said secondary winding and simultaneously to connect the second named frequency changing means to the second named tank circuit, a point of the first named tank circuit to the first named end of said secondary winding and the first named frequency changing means to the first namedtank circuit all simultaneously, a ninth one of said operable means acting upon operation to connect the first named tank circuit to the first named end of the secondary winding, the second named frequency changing means to the second named tank circuit, and a point of the second named tank circuit to the first named end of said secondary winding.-

2. In a remote control system, an alternating current distribution network, means for generating control oscillations comprising an elec- \tronic tube having an anode, a cathode and a grid electrode, a tank circuit comprising an inductance coil and a condenser for determining the frequency of the generated oscillations, a transformer having a primary winding adapted to be connected to said distribution network and a secondary winding, means for connecting the cathode of said tube to an intermediate point of said secondary winding, means including an operable switching device and at least a portion of said tank circuit for connecting said anode to one end of said secondary winding, means for electrically connecting said tank circuit across said primary winding, operable means for changing the frequency to which the tank, circuit is tuned, and means. including a second operableswitching device acting upon operation to connect the anode of said tube to'one end of said ing a primary winding adapted to be connected acting upon operation to connect a point of the odd named frequency changing means to said second named tank circuit, and the point of the first named tank circuit to the first named end of said secondary winding, a seventh one of said operablemeans acting upon operation to connect a point ing and means acting upon operation to connect a point of the second named tank circuit to said second of the second named tank circuit .to the second named end of said secondary windnamed end of the secondary winding, said secto an alternating and a secondary winding, an electronic tube oscillator'including an anode, a cathode and a grid,

a tank circuit for said tube, means for connecting the anode to a point of said tank'ci'rcuit, the cathode to another point of the tank circuit and the grid to still another point of the tank circuit,

a connection between an intermediate point of said secondary winding and the cathode, signal transmission means, means for coupling said tank circuit to said signal transmission means, a plurality of selectively operable means, one of said selectively operable means acting upon operation thereof to connect the anode of said tube to one end of' said secondary windingpa second of said operable means acting upon operation thereof to connectzthe anode of said tube to the 5 other end of the secondary winding, means connectible to said tank circuit for changing the frequency characteristics thereof; v nd a third operable means acting upon operation to connect the anode of saidtube-to one end of the secondary winding of. said transformer and said connectible means to the tank circuit simultaneously. I i

- 'STUART W. SEELEY.

current distribution network,-