US2285684A

US2285684A - Remote control system

Info

Publication number: US2285684A
Authority: US
Inventors: Stuart W Seeley
Original assignee: RCA Corp
Current assignee: RCA Corp
Priority date: 1937-10-09
Filing date: 1938-09-10
Publication date: 1942-06-09
Anticipated expiration: 1959-06-09
Also published as: GB520141A; US2245829A; FR844399A; US2177843A; CH207810A; GB516648A

Description

June 9, 1942. s. w. SEELEY 2,235,634

REMOTE CONTROL SYSTEM Original Filed Oct. 9, 1937 2 Sheets-Sheet l To a PMER sum Y I?! INVENTOR STUART W. SEELE Y ATTORNEY a radio receiver.

Patented June 9, 1 942 U'N lTED s r 'ras PATENT OFFICE I. 'annro,'ra fjfi rsisrm I Stuart w. sures, mums, N. Y. asslsnor a.

ll iadlo Corporation of Delaware original application or;

of' America. a corporation tober. 9,- 1937, Serial No. Patent No.-2,245,829, dated June 7,1941. Divided and'this application September 10, 1938, Serial No.229,260 I g "Claims. (earn-352)].

'Ihis application is a division of my copending application SerialNo. 168,180, flledOctober ,9, 1937, entitled Remote control system," now U.

S. Patent-2,245,829 issued J1me 1'7, 1941.

e -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.

ing diagram of one of the remote control boxes; and, Figure 3 is a front view of the panel of a remote control box.

tuning means, volume control means, on" and "off" controls and other major control elements of radio apparatus.

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

is found in all buildings provided with the usual 4 The nature of the methodof: remote control utilized in the arrangement described herein is such that by means of frequency and phase selective circuits and relays in the receiver unit,-

all the necessary functions for operating the receiver may be performed electrically from a remote point by means of push-buttons or switches located at the remote point. An important feat"- ure of the invention is that various carrier frequencies and arrangements of their 60, 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 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 in-' strumentality 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 settabie cam devices arranged to rotate in. unison with the tuning shaft of the receiver, provide a control for the motor 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 thepurpose of operating the-volume control device.

In addition. to the above, the invention pro-'- vides a remote control arrangement through the operation of which all of the functions necessary I to operate a receiver may be performed by plugconnections.

- lators.

v201i) or 300' k. c. Means are p'rovidedfor' reversing the phase of the 60 cycle line voltage which acts as the plate supply for the oscillator tubes so that the system is capable of feeding into the power line eitherorboth of two frequencies with .two possible phase relations of the 60 cycle modulating envelope- The resultis an intermittent series of pulses of carrier frequency modulated at 60 cycles with the interval of each pulse not greater than H of a second. This follows from the fact that each tube will oscillate only when the A. C. plate voltage applied to it is positive with respect to the tubes 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 currentrelays which-in turn cause 60 cycle power to be supplied to the motor to thereby cause it to operate either the multiple unit condenser or the volume control potentiometer.

Figure 2 of the drawings shows the oscillator, The tubes 230 and 13! together. with their associated circuits form the two oscil- Tubes 230 and 23l derive their necessary energizing potentials from the available A. .0. network by connection of polarized plug '24; to a-suitable outlet of the network. Actually plug 243 is plugged into the outlet and the turning "on" and ofl of the power supply is accomplished by-means of switch Sw located on the control box. When switch Sw is in the on 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 comprises a winding 246 and supplies the two

tubes

230 and 23| 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 push pull circuit for reasons which will appear hereinafter. I v

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 copending' application Serial No. 151,821, filed July 3, 1937', now U. S. Patent 2,177,843 (see

tubes

24 and 34, Fig. 2 of said application) is coupled to the power line through conductors 2, 3 and polarized plug-in device I. Tube 24 which may be of the 6R7 ty plays a double role in the arrangement shown in that its diodesproduce non-filtered 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-off in' the.

absence of carrier current signals. The triode plate circuit of tube 24 contains a relay 36. This relay closes switch $36 when sufllcient 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 voltage supplied to tube 24 in order for current to pass through the relay 36. r

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 k. 0. carrier applied to its grids in parallel. The insertion of tube which may be a 61-16 type rectifier tube is for the purpose of deriving sufficient grid excitation for tube 23. It should be understood that if a double triode tube with higher mutual conductance were available in place of a 6N7 it would obviate the necessity of tube 20 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, 383' in the plate circuit of tube 23. Reversal of the line voltage a'ppliedto 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 S8 to the right. A change of osciilator frequency to200 k. c. with no change in the phase of the modulating line voltage causes plate current to be understood that the function of the pushbutton switches on the control unit is to apply the-line voltage to or to shunt condensersacross, either or both of the oscillators which results in optional frequency and modulating phase relations inthe 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 a. time.

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 8 and 31- 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 by the energization of the contacts of any of the four

relays

8, 36, 31 and 38in the receiver may, for example, consist of a 23 volt capacitor type A. C; motor 92' w ich m y be geared to the condensershaft I09 or to the shaft of the volume control potentiometer I02 through suitable gear trains 95, I08' and 93, I0! respective y. Themotor circuit is I 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 turning in either direction. Operation of the motor'92 at 18 volts as when it is energized through reso as to disengage pinion 93 from the volume control gear -I0l and engage the pinion'gear is then changed back to 300 k. c. relay 36 is v energized throwing $38 to the right. It is to 95, condenser shaft gear I08. A more detailed explanation of the manner in which the motor shaft operates may be found in'U. 8. 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 startingof the motor for the selection of a desired station. In the drawings, for convenience only four cams, H0 through H3 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 I09 to positions which correspond to the stations desired for each of the cams. The manner in which the'cams control the operation of the motor and their adjustment is fully described in U. S. Patent to Garrett 1,956,419, issued April 24, 1934. Y

Turning the receiver on and of! is eifected 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 8 closes it causes a small locking relay to close the line circuit to the primary oi the receiver power transformer connected across terminals 19 and 80.

I 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 011" mechanism and the volume control mechanism as operated by means of switches etc. at the receiver without regard to the remote control feature of the invention. To turn th receiver "on it is first necessary to insert polaralso switch 03, 62 to close.

ized plug I irito a suitable outlet of the power supply'network. After this is done switch 83 is turned counter-clockwise thus causing contactor 64 to come in contact with contact point 59 and Closure of switch 63, 62 connects the two

contact strips

41 and 48 together, electrically, through

wires

65 and 66 with the result that volta'ge is put on transformer windings 44 and I5, and across terminals I9, 80. The latter energizes the receiver through the usual power transformer. Magnet I3 is also energized by connection of its winding across secondary I6. The circuit may be traced as follows:

From the left hand side of transformer secondary winding, 16 through wire I0, wire 14, relay winding I3, wire 55,

switch

56, 51 which is normally closed when the receiver is not in operation, switch 59, (now closed due to the counter-clockwise operation of lever 83) conductor 6|, conductor 69, back to the right hand side of winding I6. 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 I3 becomes de-enere gized. However, spring 53 keeps the arm 52 in the position shown in spite of the de-energization of the magnet I3. It should be understood that

elements

63 and 64 are spring contact member which act to maintain switch arm 03 in a neutral position in the absence of force tending to rotate it either clockwise or counterclockwise. and the tubes properly operating, one of the buttons I25 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, that button is pressed down and held down, thus, causin the contactor I26 to come in contact with the conductor bar I30. This completes the circuit of motor 92 across winding I6, thereby causing current to flow through the following circuit:

From the right hand side of transformer secondary winding I8, wire 69 to ground strip I30,

contactor I26, conductor I20, switch IIG 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 I4, conductor I to the left hand side of the transformer winding 18. In this way the full voltage across the transformer winding I6 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.

The motor thereby rotatesshaft I09 and, hence,

the rotcrs 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 99 to the right against the action of spring 91, thereby short circuiting contactors 30 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 resented by cams IIO through II3. When cam II2 which corresponds to 'the push-button I26 is rotated to a position which causes the switch H6 to open, thatis, to a position where both the upper terminal and the lower terminal thereof are open (see position of switch I) 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 correspond- To tune in a station after the set is on ing to push button I25, then I would be depressed and held down, thus causing the motor circuit to become energized through the following electrical path: I I

From right hand side of transformer winding I6, conductor 69, bar I30, contact device I25 (now in contact with I due to depression of button I25), conductor H9, switch H5 which, as shown, contacts its upper terminal owing to the fact that the cam follower is riding on the through motor 92, conductor 14, conductor I0, to

., the left hand side of the transformer winding I8. 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 I I I breaks contact at switch I I5,

After a station is tuned to and signals arev received, it may be necessary or desirable to vary the volume either up or down for proper'enjoymentof the signals. For this purpose, the switch 83 is used. Operation of this switch counterthrough the following circuit:

that the motor 92 is caused to rotate in one di- I Left hand side of the transformer winding I5, conductor I0, conductor I4, motor 92, conductor I-Il, resistor R1, conductor 68, switch 59, 64 (now closed), conductor 6| and conductor 69 to the right hand side of transformer winding I5. Resistance R1 acts to reduce the voltage applied to the motor 92 with the result that gear 93 stays in engagement with gear 1 IM 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 83 is allowed to return to its normal middle position which is the position shown in the drawings, thus breaking the

contact

59, 64, which stops the motor 92. If it is desire 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:

From left hand side of transformer winding I6, conductor I0, conductor I4, motor 92, conductor I18, resistor R2, conductor-51, switch Iii], 64 (now closed), conductor 6i, and conductor 09 to the right hand side of transformer winding I6. 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 inwith gear wheel III. However, the motor 92 will rotate in the opposite direction and rotate the movable arm I08 oppositely to the-previously described volume control operation, thereby reducing the volume. when the desired volume is reached switch 88 is allowed to return to its normal released position, thus breaking the motor circuit. To turn the receiver off button I19 is depressed which 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 6| and wire 68, back to the right hand side of transformer winding 16. Energization of relay 12, flips the arm 52 counterclockwise, thus opening

switch

48, 50 and thereby disconnecting contact bars 41 and 48 whichdeenergizes 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 push-but-' tons 200-208 is to connect circuits tothe oscillator tubes 280 and 28I 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 the 60 cycle A. C. plate voltage to give various combinations of output frequency and modulating phase a to the controlling energy fed into the power line.

switch 260 is both the "on" button and the volume up button. Push button 208, which when depressed closes switches 221, 228 and 220 and switches 226 from its upper contact position to its lower contact position, is the of! 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 various switches 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 de-' pressed closing switch 260 thereby connecting the top side of secondary winding 246 to the tap 286" on coil 286. By this means a 60 cycle A. C. voltage is applied as plate supply for tube 280. This will cause the tube to oscillate at a frequency determined by the resonant circuit 286, 281 which in this case is 300 k. c. Application of the 60 cycle voltage permits tube 280 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 288 is coupled into the A. .C. power line through the connection including coil 288 and condenser 242. The energy thus fed into 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 M of a second in duration. This energy is transmitted to the receiver Fig. 1 through the A. C. power line and enters the control circuits in the receiver through polarized plug I. Tube 6 is arranged by means of its connection to the polarizing potential divider 4, I 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 6, I0 tuned to 300 k. c. is all that is required to initiate a discharge between the auxiliary electrodes AUi and A'Uz. As a result of this discharge the gap between AU: 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 time relation with the peak 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 St 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 8|, 82.

When this happens A. C, voltage is applied to the primary of the receiver power supply transformer through terminals 19 and 80 as well as to the winding 15,- the latter being '

wthrough conductors

11 and 46. across secondary winding 16 and causes relay winding 18 to be energized thereby pulling arm 5I over to the-right as shown closing switch 48,

50 which shorts the

bars

41 and 48. At the

same time switch

66, 51 is opened to thereby remove voltage from coil 18 and prevent its becoming overheated, while the receiver is on. Relay 18 is energized throughthe following circuit:

Left side of 16, wire 10, wire 14;, coil 18, wire 55,

switch

56, 51, wire 58, wire 68, contacts I8I, I60 of Szswire I6I, contacts I81, I51 of Sn, wire I68, contacts I48, I54 of S35, wire I65, contacts I48, I52 of Se (bearing in mind that S; 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 howto select a particular station: station as, for instance, to the station corresponding to button 20I (Fig. 2) this'button is pressed down, thus closing

switches

208 and 2 l0. Closure of 2I0 connects the plate supply voltage to tube 230 asiollows:

Upper terminal of 246 through wire 246, wire 252, switch 2I0, wire 25I, wire 280 to the tap on coil 286. .That causes tube 280 to oscillate at a frequency determined by 286, 281 (say 300 k. c.)

with a certain phase of the 60 cycle modulating envelope. Since 206 is also closed'by depressing button 20I, oscillator tube 28l is also'supplied with A. C. plate voltage by a connection from the bottom half of winding 246, conductor 250 closed switch 226, conductor26l switch 208 (which is closed due to the depression of button 200, con ductor 226', conductor 258 to tap 285 on coil 285 and oscillates at a frequency determined by 286 and 284 (300 k. c.) The oscillations in tube 28! appear only during those portions of the A. C. 60 cycle current when the plate of tube 28I is positive with respect to its cathode.

Since plate voltage available for application to tube 280 is-out of phase with that available to tube 28l because of phase relation between opposite ends of transformer secondary 246, it follows that the envelope of the output voltage which appears in the output of tube 280 Voltage is thus developed To tune to a aasaeac g is out of phase with the envelope of the output of tube 23I. 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) and throwing switch Sa 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 10 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 '15 which is connected across the line 2, 3. The phase arrangement is such that modulated (300 k. c.) carrier which appears across coil I5 due to resonant rise in circuit I5, I1 and coupled to coil I3 causes tube 24 to pass ciirrent 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 25 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 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 35 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 40 a predetermined station which is the same as the station corresponding to button I24- when the receiver is operated 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 59, wire I15, through contacts I52,

I48 of switch 58, wire I; contacts 154, I43 of Sn, wire I63, through contacts I51, I31 of Sn,- wire IBI, contacts I60, I32 of S35, wire I51, wire IIB, cam switch II4, lower contact of switch H4, wire I18, motor 92, wire 14 and wire 10 to the left side of winding 16.

The full voltage across 15 is thus placed across the motor which causes motor shaft 94 to be 55 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 H4 the motor stops and the armature slides back to its original position as shown in the drawings, thereby allowing spring 91 to draw back spring contact 99 and so remove the shortcircuit from terminals 30, 30'.

Referring again to Figure 2, if a station corresponding to push-button 205 had been desired, then this push button is depressed closing switches 2I6,'2I1 and 22I.

Closure of switch 22I has exactly the same action on oscillator tube 230-as switch 2I0 had in the previous description. This means that the output of oscillator 230 is composed of a modulated series of pulses with a carrier frequency of 300 k. c. Oscillator tube 23I now has its output frequency changed from the 300 k. c. emitted 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 2I1 in the following manner.

Starting at the cathode terminal on coil 235, through wire 253, wire 225', switch 2I6, switch 2", wire 263, wire 255,. through condenser 233 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 S31 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 ,tlte A. C. 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. T

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 mutual conductance of tube 23 was not sufficiently high to permit obtaining the desired sensitivity. A

-mote 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 9 having been energized and subsequently having ,thrown to the right their associated switches S31 and 88, cause a new station to be tuned. The motor 92 is energized through the following circuit:

Right hand side of winding 15, wire 59, wire I15, contacts I52 and I48 of Se, wire I55, contacts I54, I43 of S38, wire I65, contacts I51, I38 of S37, wire I10, wire I2I to cam switch II1.

It will be noted that both the upper and lower contacts of switch I31 are open. 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 heat the tube cathodes of the receiver.

If instead button 202 is depressed, switches 2H and 2I2 are closed. They cause oscillator 230 to be energized and to feed into the power line carrier frequency of 200 k. c. modulated at 60 cycles in a phase which would cause tube 5 to operate if the frequency had not been changed from 300 k. c. to 200-k. c. This energy will be stepped up by resonant circuit I4, I5 (Fig. l) and will cause the modulation envelope to appear on the grids of tube 25. The phase of the plate voltage on the top section of tube 25 is so arranged that current passes through relay 55 energizing it, causing Ssa 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 cam III on shaft I55.

It should now be apparent that the function of the push buttons MI, 202, 205, 205, 205 and 201 is to alter the output frequency and the modulating phase of the voltage developed in the oscillation generating circuits comprising tubes 250, 23I and their associated circuits.

The resultant voltages act upon different combinations of tubes shown in Figure 1 and cause energization of several possible combinations of relays which in turn cause to be connected electricallyfrom a remote point, the same contacts 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 beenturned on" 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. v

If it is desired to increase the volume, button 200 is depressed. This performs the same function electrically as when the receiver is turned on by means of depressing button 200, in other words, switch 250 is closed supplying oscillator tube 250 with plate potential. This generates carrier frequency of 300 k.'c. modulated with 60 cycle plate voltage as previously described. The generated energy is transmitted over the I A. C. power lines and is picked up in the receiver circuits of Figure l, causing tube 5 to be ignited and relay 8 to be energized thus throwing switch S8 to the right. The motor circuit is thereby energized causing the motor 52 to run at reduced speed whereby the setting of the volume control potentiometer is effected in the following maner I Current flows from the right side of 15, wire 55, wire I15, contacts I52, I of Sn, wire I55, contacts I54, I45 'of Sn, wire I55, contacts I51, I51 of Sn, wire I5I, contacts I50, I5I of Ba, wire 55, resistor RI, wire I11, motor 92, wire 14, wire 10 to left side of 15. g

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

there is insufficient axial thrust of shaft 94 to cause axial differences and the motor gear remains engaged to volume control gear I5I. Rotation of the motor causes shaft I02 to rotate thereby moving the movable arm I05 of the potentiometer along resistance I04. Wires I05, I05, I01 may be connected to the audio system in the receiver in such a way that variations of the position of arm I55 on element I54 cause variations in the volume output of the receiver.

It should be noted that current cannot flow through relay 15 because

switch

55, 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 205 the first time.

If it is desired to run the volume down" then button 204 is depressed, closing switch 2I5 and thereby energizing oscillator 25I which emits a frequency of 300 k. c. modulated by a cycle voltage in the opposite phase to that used to modulate 250 in the preceding illustration of increasing the volume. I The 300 k. c. 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 55. It is to be noted that tube 5 does not operate because the phase of the modulation envelope is not correct to initiate a discharge in this tube. Relay 55 being energized, switch Su is thrown to theright. Motor 52 now runs at reduced speed in a direction opposite to of winding 10.

The action is the same as that which causes the volume to be increased except that the motor now ms in reverse direction, thus causing arm I05 to decrease the volume.

Toturn the set "off" from the remote point, button 255 is depressed, thereby moving switch 225 from its left hand position shown to its right hand position and at the same

time closing switches

221, 225 and 225. Whenthis happens the electrical action is such as to cause oscillator 255 to operate at 300 k. c. with the normal phase of A. C. voltage supplied as plate supply. Oscillator 250 is now made to run at 300 k. c. due to the energization thereof through the following circuit:

From the top winding 245 conductor 245'closed switch 225 (switch in its right-hand position), closed switch 221, conductor 25I, conductor 255 to tap 255' on the coil.255. The'circuit is completed through ground since the center tap of'secondary 245 is connected to ground and the cathode 'of the, tube 255 is connected to ground.

' which'are mutually out of phase.

ed across part of the coil 235 through the followcausing the motor to rotate until the cam comes in the position to break the cam switch, as described hereinbeforel its modulating plate supply voltage is reversed from that of any previous condition explained and is now in phase with the A. C. 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. 0. power line as a transmitting medium two frequencies, 200 k. c. and 300 k. 0., 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 5 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 through relay 38 when 200 k. c. modulated in the phase resulting from the action of pressing 208 in Figure 2 is applied. Consequently, relays 8 and 38 are energized throwing I 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 thisfunction is as follows:

From the right side of IS, wire 89, wire I15, contacts I52, I48 of Se, wire I65, contacts I54, I44 of S38, wire I I coil I2, wire I0 to left side of winding I6.

If the station corresponding to button 206 is desired, this button is depressed, closing switches 2I3, 222 and 223. This will cause oscillator 230 to operate at 200k. c. and oscillator 23I to operate at 300 k. c. with A. C. modulating voltages The resultant output energy transmitted through the power line acts upon the following circuits in the receiver:

The 200 k. 0." energy is pickedup bycoil 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 Saa' to be thrown to the right. At the same time the 300 k, 0. componentof energy acts on the grid of tube 24 whose plate voltage is properly phased to cause current to flow through relay winding 38 energizing it and throwing $36 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 similar manner as cam switches II4 through 1,

To tune to a station corresponding to button 201, this button is depressed, closing switches H9, 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 31 and 38, throwing switches S31 and $38 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 to 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 return to itsnormal 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 sufliciently to give the desired vol r me at which time the depressed button is released. To control the volume locally the lever 85 of Figure 1 is turned clockwiseor 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 84. 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 "off" requires 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 anotherthereby 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 adapted to be remotely controlled.

I claim: 1' r 1. In a remote control system which is operable over an alternating current power supply network upon xahich, in addition to the usual alternating current wave, are impressed control oscillations occurring during alternate half cycles of the alternating current wave for performing one desired controlling action and control oscillations occurring during the opposite half cycles of the alternating current wave for performing another desired controlling action, an operable relay device including a gas discharge tube adapted to be connected to said network and innamed circuit including means whereby said elec-.

tronic tube becomes excited sufliciently to operate the second relay device upon connection thereof to the network by the first named relay device only when control oscillations occurring during said opposite half cycles of the alternating current wave are present upon the network.

2. In a remote control system, an alternating current power supply network upon which are impressed any one of the following control currents in addition to the usual alternating current wave: (1) control currents occurring during alternate half cycles of the alternating current wave; (2) control currents occurring during the opposite half cycles of the alternating current wave, a gas discharge tube connected to said network so as to be energized during alternate half cycles of the alternating current wave and to dis-' charge when there is present on the network control currents occurring during said alternate halt cycles of the alternating current wave, a relay device operable by current passing through said gas tube when the same discharges, an electronic tube, and means acting upon operation of said relay device for connecting said electronic tube to the power supply network to energize the tube.

3. In a remote control system which is operable over an alternating current power supply network upon which, in addition to the usual altemating current wave, are impressed control currents occurring for one particular desired controlling action during alternate half cycles of the alternating current wave and for another particular desired controlling action during the opposite halt cycles of the alternating current wave, a gas discharge tube, means for connecting said tube to said network, means connected to the tube to cause the same to discharge when there is present on the network control currents occurring during said first named alternate half cycles of the alternate current wave, a relay device operable when the gas tube discharges, an electronic tube, means acting upon operation of said relay device to connect said electronic tube to the power supply network'to thereby provide.

the tube with proper energizing potentials ineluding a potential for biasing said electronic tube at cut-oi! and thereby prevent current passing through said electronic tube, and means for overcoming said biasing potential when there is present on the network, control currents occurring during'said opposite half cycles of the alterhating current wave.

4. An arrangement as described in the next preceding claim in which arelay device is associated with said electronic tube, said relay device operating after said electronic tube is connected to the power supply line by operation of the first named relay device only in the presence of control currents during said opposite half cycles of the alternating current wave.

5. In a remote control system which is ope able over an alternating current power supply I during said opposite half cycles of the alternating current wave, a gas discharge tube, means for connecting said tube to said network, means connectedto said tube to cause the tube to discharge when there is present in the network one of said four control oscillations, a relay device operable when the gas tube discharges, an electronic tube, means acting upon operation of said relay device to connect said electronic tube to the power supply network and thereby provide the tube with proper energizing potentials including a potential for biasing said electronic tube at cut-oi! and thereby prevent current passing through the electronic tube, means for overcoming'said biasing potential when there is present upon the network one of the otherof said four control oscillations, a second electronic tube arranged to be connected to the power supply network upon operation of 'said first named relay device, said second electronic tube being also biased at cut-of! to prevent current passing through the tube, means for overcoming said last named bias when there is present upon the network, control oscillationsof a third one of said four oscillations, a third electronic tube arranged to be connected to the power supply network upon operation of the first named relay device,

said third electronic tube being also biased at cut-of! to prevent current passing through the tube and means for overcoming said last named bias when there is present upon the network control oscillations of the remaining of said fouroscillations.

6. In an arrangement as described in the next preceding claim, individual relay devices associated with each of said electronic tubes each thereof becoming operative upon passage of current through its associated tube.

7. In combination with an alternating current network, a relay connected to said network and arranged to be energized by the alternating current of said network, means rendering said relay responsive only to oscillations impressed thereon of a first predetermined Irequency different from the network frequency, a second relay adapted to be energized by connection thereof to saidnetwork, means rendering said second relay responsive only to oscillations impressed thereon of a ing said relay responsive only to oscillations iming upon operation of the second relay for effecting the operation of said electrical device.

8. In combination with an alternating current network, a relay connected to said network and arranged to be energized by the alternating current of said network, means rendering said relay responsive only to oscillation impressed upon the network of a first predetermined frequency different from the network frequency, a second relay adapted to be energized by connection thereof to said network, means rendering said second relay responsive only to oscillations impressed upon the network of a second predetermined frequency different from both the network frequency and said first frequency, means acting upon operation of said first relay for con necting said second relay to the network to enerpressed thereon of a first predetermined fre-.

quency different from the network frequency and occurring during a predetermined set 'of alternate half cycles of the" network alternating current wave, a second relay adapted to be enersized by connection thereof to said network, means rendering said second relay responsive only to oscillations impressed thereon of said first predetermined frequency and occurring during the opposite set of' alternate half cycles of the network wave, means acting upon operation of said first named relay for connecting said second relay to the network, a plurality of selectively operable electrical means, means acting uponoperation of said second relay for operating one of said selectively operable electrical means, and means acting upon simultaneous operation of both said first and second, relaysfor operating another one of saidselectively operable electrical means. I

10. In a remote control system, an alternating current network, a relay connected to said network and arranged to be energized by the alternating current of said network, means rendering said relay responsive only to oscillations impressed thereon of a first predetermined frequency difierent from the network frequency and occurring during a predetermined set of alternate half cycles of the network alternating current wave, a second relay adapted to be energized by connection thereof to said network, means rendering said second relay responsiveonly to oscillations impressed thereon of a second predetermined frequency different both from said first frequency and said network frequency and occurring during said set of alternate half cycles of the network wave, means acting upon operation of said first named relay to efiect the energization of said second relay by connection thereof to the network, a plurality of selectively operable electrical means, means for operating one of said selectively operable electrical means upon operation of said second relay, and means for operpressed thereon of a first predetermined frequency different from the network frequency and occurring during a predetermined set of alternate half cycles. of the network alternating current wave, a second relay adapted-to be energized by I connection thereon to said network, means rendering said second relay responsive only to oscillations impressed thereon of a second predetermined frequency different both from said first frequency and said network frequency, and. oc-

curring during the opposite set of alternate half cycles of the network wave, means acting upon operation of said first named relay to-eifect theenergization of said second relay by connection thereof to the network, a plurality of selectively operable electrical means, means for operating one of said selectively operable electrlcal'means upon operation of said second relay, and means for operating another one of said selectively operable electrical means upon operation of both said-first and second relays.

12. In a remote control system, an alternating current network, a relay energized by the alternating current of said network, means rendering said relay responsive to oscillations impressed thereon of a first predetermined frequency different from the network frequency and occurring during a predetermined set of alternate half cycles of the networkalternating current wave, a

' second relay adapted to be energized by connection thereon to said network, operable switching means for connectingsaid second relay. to said network, means rendering said second relay responsive to oscillations impressed thereon of a second predetermined frequency different from the network frequencyas well as fromv said first predetermined frequency and occurring during a predetermined set of alternate half cycles of the network alternating current wave, means acting upon operation of said first named relay for causing said operable switching means to connect the second relay to the network, and operable switching means adapted to be operated by said second'relay upon operation thereof.

13. In a system as 'describedin the-next preceding claim, a means operable in one position to efiect a predetermined operation and in another position to effect a second predetermined operation, said last named means being operated to to one, of said positions upon operation of said first relayand to the other of said positions by the simultaneous operation of both said first and second relays.

14. In a remote control system, an alternating current network, a relay connected to said network and arranged so as to be energized 'by the alternating current of said network, means rendering saidrelay operative when oscillations of a predetermined frequency are impressed thereon, a second relay adapted to be energized by connection thereof to said network, means renderingsaid second relay operative when oscillations of a predetermined frequency are impressed ating another one of said selectively operable electrical means upon operation of both said first and second relays.

11. In a remote control system, an alternating nating current of said network, means render;

thereon, operable means acting upon operation of-said first named relay to effect the energization of said second relay by connection thereof to the network, follow-up switching means act ing in response to the operation of said operable means for maintaining a connection between the second relay and the network irrespective of the condition .of said first relay, and means acting upon the simultaneous excitation of both said,

. first and second relays to render said follow-up means inoperative to'maintain the connection between said second relay and the network. 15. In a system as described in the next preceding claim, a load, and means including said follow-up switching device for maintaining a connection between said load and said network, at the same time that said second relay is con-v ,nected to the network.

16. In combination with an alternating current distribution network, a, relay connected to and adapted to be energized by the alternating current in said network, means rendering said relay responsive to oscillations impressed thereon of a first predetermined frequency difierent from the network frequency and occurring during a predetermined set of alternate half cycles of the network alternating current wave, a second relay adapted to be energized by connection thereof to said network, means rendering said second relay responsive to oscillations impressed thereon of a second predetermined frequency different from the network frequency and from said first frequency and occurring duringsaid set of alternate half cycles of the network wave, a third relay adapted to be energized by connection thereof to said network, means rendering said third relay responsive to oscillations impressed thereon of said first frequency and occurring during the opposite set of alternate half cycles of the network wave, and a fourth relay adapted to be energized by connection thereof to said network, means rendering said fourth relay responsive to oscillations impressed thereon of said second frequency and occurring during said opposite set of alternate half cycles, switching means'operable upon operation of said first relay the alternating current derived from the network, I

coupling means for rendering said relay responsive only to control oscillations impressed upon the power supply network of a first predetermined frequency different from the frequency of the power supply network alternating current, a second relay, operable means for connecting said second relay to the power supply network to energize the same, coupling means rendering said second relay responsive only to control oscillations impressed upon the power supply network of a predetermined frequency different from the frequency of the power supply network alternating current, means responsive to oscillations of said first predetermined frequency upon the power network for exciting said first relay, means acting upon excitation of said first named relay for connecting said second relay to the power supply network to energize the second relay, said first named relay including a gaseous tube having main electrodes situated therein to form a discharge gap and an auxiliary electrode arranged to form an auxiliary discharge gap with one of said main electrodes, the main electrodes being connected across said power supply network whereby a potential derived from said network for connecting said other relays to said network is maintained across the main electrodes, said potential being of too low a value normally to ionize said gap and start a discharge therebetween, means for applying a biasing potential upon said auxiliary electrode derived from the power supply network potential, means for impressing the control oscillations upon said auxiliary electrode, said biasing potential being of such value that upon application of the control oscillations upon said auxiliary electrode, the

auxiliary discharge gap becomes ionized thereby initiating a discharge between the main electrodes.

STUART W. SEELEY.