US2457730A - Relay control system - Google Patents

Description

Dec. 28, 1948. G. G. ROBERTS 2,457,730

RELAY 'cbn'TRoL'sYs'rEM Fi ed Au 29, 1942 I Q 2 Sheets-Sheet 1 INVENTOR Gerald G- Roberts BY M102;

ATTORNEYS Dec. 28, 1948. ROBERTS 2,457,730

RELAY CONTROL SYSTEM Fi 'ed Aug. 29, 1942 2 Sheets-Sheet 2 F E INVENTOR Gerald G. Roberts ATTORN EYS Patented Dec. 28, 1948 UNITED STATES PATENT OFFICE RELAY CONTROL SYSTEM Gerald G, RObertmAkromOhin, assignor to William ONeil, Akron, Ohio;

Application August 29, 1942; Serial No..456,'630

7 Claims. 1

This application is a continuation-in-part of my application Serial No. 415,398, filed October 17, 1941 Patent No. 2,330,241, granted September 28; 1943. The invention relates to a communication system and more particularly to a radio control device which may be remotely operated in response to transmitted radio frequenciesto perform various functions or to insure the reception of special messages.

It is frequently desirable, especially in modern warfare, to have devices capable of being operated from a central control station. Thus in tanks which are deployed in the field of battle it is desirable to give a plurality of visual or audible signals from a central station to warn the operator or to cause the operator to change directions, etc. In order tohave a control devicecapable of performing a large number of functions, it'is almost necessary that the individual control elements which operate the separate functions be each responsive to a definite frequenc or at least to a very limited band of frequencies. It is almost mandatory if the device to be controlled is subject to appreciable vibration that the control devices be free of mechanically tuned'apparatus which might be affected by jars or mechanical vibrations of certain frequencies.

Remotely operative radio control devices have heretofore been proposed to operate switches'and perform various functions. The control devices heretofore proposed, however, have been objectionable for the reason that they are responsive to too wide a band of frequencies and for the reason that they are adversely afiected by vibration so that they cannot be used for controls'oi tanks or for giving signals where substantial vibration is experienced.

It is an object of the present invention to provide a radio control device which is responsive to definite modulations of radio frequencies to remotely operate mechanical elements or'to insure reception of special messages and the like.

It is another object of the present invention to provide a radio control device responsive'to definite modulations of radio waves and which isnot affected by jarring, so that it may be used in tanks, aircraft and the like.

It is another object of the present invention to provide a radio control device having a plurality of control elements, each responsive to definite modulations or a small band of modulations in carrier frequency to accomplish a given result.

It is a further object of the present invention to provide a radio control device which when connected to the output of a suitableradio receiving 2" set wllloper-ate'in response to a particular frequency or very small band of frequencies carried as modulations on the radio-waves to-which the radio receiver is tuned to operate a switch or given control'mechanism, but which is'notresponsive to frequencies outside of said band.

It is astill further object of the present invention to provide a pluralit of'radio control devices which may be connected to-the'audiooutput of a' radioreceiver, each of which is only responsive-toa definite narrow'band of modulations in the radio wave" to which said receiver is tuned cooperate-a givencontrol-device or to performa given-function.

Other objects will be apparent from-thefollowingdescription of the drawing, in which:

Figure 1 is a schematic diagram ofa control device embodying the present invention and'employing two circuit portions; and

Figure 2 is a schematic diagram-of a control device employing a greater number of circuit por tions to permit'functional operations responsive to more than two control frequencies.

Control or signal devices embodying thepresent invention comprise'essentially a plurality of circuit portions, each portionhaving connecting meansfor connection to asuitable power supply;

a grid-controlledelectronic tube connected to said connecting meansand adapted to pass plate current from said power supply or to substantially prevent current fljow, depending on the potential appliedto saidggrid; a relay operatively'controlled by a change in said plate current; separating meansfor separating an impedance potential due to signals ofone of a plurality of control frequenciesya rectifier for said separating means for obtaining arectified" current due to said impedance potentials causedby said control frequencies; and meansfor impressing'a'potential dropdue to said rectifiedcurrent on the grid of an electronic-tube in another of said circuit portions, so that when a control signal'within one particular narrow band offrequencies is passed into said signal device a potential due to the'signalis separated anda negative potential is applied to the grid of an electronic tube in one of said circuit portions, and when another control signal within another narrow wave-band is passed into said signal device a negativepotential is applied to the grid of, an electronic tube in-the other of said circuit portions. The plate current in each of said circuit portions maytherefore be controlled by transmission of separate control frequencies to said. device;

Preferably, each circuit portion of the control device of the present invention-also-comprises an amplifier for increasing the separated potential due to each control frequency, means connected into the plate circuit; of said amplifier for separating the amplified potential due to said control frequency, means for impressing the amplified potential thus obtained on said rectifier and means for smoothing the wave-form or for delaying the rectified current.

Referring to the drawings, in which like parts are indicated by like numerals of reference throughout the several views, and more particularly to Figure 1, the control or signal device embodying the present invention may be suitably connected to the audio output of a suitable radio receiver I, such for example as a three-tube receiver having a mixer tube, one stage of I. F. diode-detector and a high mu, high impedance audio tube. The output or audio tube of said receiver may for example be designated as T with a plate 2. The negative terminal of the power supply as Well as of the cathode of the tube T may be grounded. The positive terminal of the power supply is designated as B+.

. The control or signal device of the present invention is responsive to at least two control frequencies to cause at least two functional operations. The two circuit portions are designated generally as A and B; each circuit portion has suitable connecting means, such as wires 3a and 3b, respectively, to power supply B+. Suitable grid-controlled electronic tubes Va and Vb of the respective portions A and B are suitably connected through said connecting means to said power supply and are adapted to pass plate current from said power supply or to substantially prevent plate current, depending upon the potential applied to grid 1 thereof. The relays R9. and Rh are operatively controlled by the electronic tube of the respective circuit portion or by the plate current thereof.

For each circuit a separating means such as a tuned circuit or network 4a and 4b is provided to obtain a potential drop due to one of said control frequencies. The circuit constants as determined by the inductances and capacitors L1 and C1 of the circuit 4a and L2 and C2 of the circuit 41) are difierent so that the networks 4a and 4b are tuned to resonance for different control frequencies F1 and F2, which may be transmitted as modulations of theradio frequency to which the receiver I is tuned. The networks 4a and 4b are connected through respective isolating resistors 5a and 5b to a coupling condenser 6 which makes connection to the plate 2 of the tube T, or to other suitable supply or line over which control signals are to be sent, and permits passage of only alternating current or the variable portion of the output or plate current of the receiver I. An amplifier, to amplify any potential drop across the network due to the presence of a control current of frequency corresponding substantially to that to which the particular circuit 4a or 4?), etc. is tuned, especially when used with an additional filtering or tuned circuit to separate amplified potential, markedly increases the sensitivity or selectivity of the device. In the circuit shown, the tubes Va and Vb are of the remote cut-off pentode and duodiode type; such tubes are desirable in that they may perform the functions of the grid-controlled electronic tube, as well as those of the amplifier and rectifier. Thus, when the grid potential is sufficiently positive to permit passage of plate current, the tubes Va. and Vb may serve as amplifiers to amplify the voltage drop across the respective networks to and 4b, respectively,

4 due to a control frequency to which the particular network 4a or 41) is tuned. Means such as a coupling condenser 8 or 811 and suitable connector are therefore provided for suitably connecting a positive portion of the respective network 4a or 4b to the grid 1 of the appropriate tube Va or Vb.

A second tuned network 9a and 911, having respective inductances La and L4 and respective capacitors C3 and C4 in the circuit portions A and B, so selected that its closed circuit is tuned to the same control frequency F as the network 4a or 41) of the same circuit portion, is connected into the plate circuit of the tube Va or Vb of each of the circuit portions A or B, respectively. The network 9a or 9b together with the condenser Illa or [0b serves as a means for separating the D. C. plate current of the tubes Va or Vb from the amplified potential drop due to amplified current of the control frequencies F1 or F2 to which the circuit 4a or M; of the respective circuit D01- tion is tuned. Connecting means, including the wires [2a and i217, which are respectively connected to the more negative terminal of the respective tuned circuits 9a and 5b, are provided for applying the voltage drop across the circuit 9a or Eib to the respective terminals l3a and |3b of the diode rectifier in the appropriate tube Va or Vb. The more positive side of the networks 9a and ill) are preferably connected to the respective accelerating grids Ma and Mb. The diode rectifier serves as means for rectifying the current due to the control frequency.

Filtering or delaying means, comprising suitably arranged resistors [5a or [51) and l'la or llb together with a condenser 18a or I8b, is preferably connected to the diode rectifier. The filtering means serve to smooth out the wave-form of the rectified current due to amplified potential drop caused by the control frequencies and to provide the desired delay, so that the control device is not responsive to control signals unless they are transmitted for a reasonable period of time. Means such as a wire 20a or 202) and a resistor Zia, or Zlb are provided for connecting the rectifier or said filtering means to the grid of an electronic tube in a cooperating circuit portion- Thus, when only two circuit portions are used, a wire Ella and a resistor 2Ia make connection between the grid 1 of the tube Vb of circuit portion B and the ungrounded side of the condenser lSa in the circuit portion A, whereas the resistor Nb and the wire 20?) serve as means for connecting the ungrounded side of the condenser 18b to the grid of the electronic tube in the circuit portion A.

The respective coils 23a and 23b of the relays Ra and Rh, preferably with a by-pass resistor 24a or Mb, may be connected in series with the plate lie or 25b of the electronic tube of the respective circuit portion, so that plate current from said tube passes through the coils 23a or 2327 to operate the respective relay.

In the operation of the devices of the present invention, signals or modulations transmitted by the station to which the radio receiver l is tuned pass from the output thereof through the coupling condenser 6 through the isolating resistors 5a and 5b to the networks 4a and 4b. If the frequency of the signal received corresponds substantially to frequency F1, to which the circuit 4a is tuned, circuit 411 operates as a high impedance and a substantial potential drop is produced between terminal l25a and the ground. If the freqency of the signal received differs substantially from the frequency F1, the circuit 4a allows ittopass to ground without appreciable potential drop;

The potential due to the frequency F1 is applied through the condenser 8 to the grid 1 of the tube Va, It appears in amplified form across the network 9a, also tuned to frequency F1 and connected in the plate circuit of thetube Va. The potential drop across the network 9a is applied through the coupling condenser Ma to the diode rectifier I3a.

The negative direct current voltage developed at the diode is delayed and its Wave-form (smoothed by the resistances l5a and I'la,together with the condenser l8a. It is applied to the grid "of the tube Vb in the cooperating circuit portion B. This negative voltage causes the normal plate current of the tube Vb to cease, de-energizing the relay coil 23b and causing operation or movement of the relay Rb so that contact is made between contacts and 3|. Closure of the contacts '33 and 3| permits current to flow from the power supply P along wires '32 between contacts 33 and 34 of the relay Ra along wires 35 and 36 through a coi1 3! of the relay R, causing it to close and cause one of the functional operations of the control device. The relay 'R may,for example, operate a plurality of switches and preferably has holding means, such as contacts 38 and 39 which are connected in parallel with the contacts 30 and 3| of the relayRb for maintaining closure, so that upon closure of the relay R it is held closed regardless of the position of the contacts 30 and 3|.

It is seen that except for the short interval of time required to cause initial operation of relay Rb, transmission of the control frequency F1, to which network 4a is tuned, may be discontinued or it may be transmitted at suitable periodic intervals to cause periodic operation of relay Rb without interfering with the connections initially established. Thus F1 is available and may be used for sending of code messages or with the aid of the flapper of the relay Rb and a suitably attached ratchet switch to accomplish additional functional operations.

If a signal is received of frequency corresponding to frequency F2, to which the network 4b is tuned, a substantial potential drop is obtained between the terminal I25?) and the ground. This potential drop is amplified, rectified and delayed similarly to the potential drop due to the frequency F1, and after passing through the delay network, comprising the resistors 15b and Nb and the condenser 3b, is applied as a negative voltage to the grid 7 of the tube Va, causing cessation of plate current therein and de-energization of the coil 23a of the relay Ra, breaking contact between contacts 33 and 34, and causing deenergization of the coil 3! of the relay R and causing opening of the circuits closed by the previous operation of the relay R.

As shown in the drawing, the operation of the relay B may be utilized to provide any desired number of functions; thus, closure of contacts at and. M permits power to be obtained between terminals 52 and 43, which may be respectively connected by wires I I0 and III to any desired apparatus lo]. Closure of contacts 44 and 43 permits power to be obtained between terminals 46 and 4?, which may be respectively connected by wires H2 and H3 to any desired apparatus Hi0. Contacts 48 and 49 are a power switch in parallel with that of a standard receiver, such as that schematicallydesignated by numeral 30 and having two tubes I02 and I33,- as shown.

A contact 61 may :be connected to the input or grid of a suitable audio stage of the receiver 5.. a contact '52 may be connected to the output of anintermediate tube of the standard receiver, and a contact 53 may be suitably connected 'to the output of the auxiliary or midget receiver I, so that upon energization of the coil of the relay R connection is broken between the contacts 54 and 52, disconnecting the radio frequency stages from the audio of the receiver, and made between contacts 5| and 53 connecting the output of the midget receiver to the audio stages of the standard receiver 50. It is thus 'seen' that in response to a signal of a frequency F2 with the arrangement shown, the broadcast to which the midget receive-r may be fixedly tuned will be immediately heard through the standard receiver 50, even though the latter is tuned to a station other than that to which the midget receiver'is fixedly tuned. In response to a signal of frequency F2, the standard receiver is again connected to its normal radio frequency stage.

The modification shown in Fig. 2 illustrates the method of connecting additional circuit portions, such as circuit portion C, so that the relay of each portion is operatively controlled by a given control frequency Or by transmission of modulations of a given control frequency in a radio carrier wave to which the radio receiver I is tuned. The connections to the contacts of relays Ra, Rb and Re of the respective circuit portions A, B and C may be arranged in any desired manner, depending on the functional operation desired. It will be seen that a more negative portion of the rectifiers in each of the circuit portions is connected to the control grid of only one electronic tube in another circuit portion. Thus, the rectifier l3a of the circuit portion A is connected in series through the delay network comprisin the condenser la and resistors l5a and Ila, the resistor Ma and the wire 20a to the grid 1c of electronic tube Vc; the rectifier l3b of the circuit portion B is connected in series through the delay network comprising the condenser lb and the resistors l5b and llb, the resistor 2lb and the wire 20b to the grid 1 or the tube Va; and the rectifier 130 of circuit portion C is connected in series through the delay network comprising the condenser I and the resistors I50 and He; the resistor Ho and the wire 200 to grid 1 of the electronic tube Va. Thus the relay Re. is responsive to frequency F2; relay Rb is responsive to frequency F3 to which circuit 4c is tuned; and relay Re is responsive to frequency F1.

While I have shown control devices having only two and three circuit portions inthe drawin'gs, it is obvious that the number of circuit portions may be increased as desired to accomplish any number of functional operations. A single circuit portion in a single cut-off frequency may be used to stop current flow in all desired circuit portion-s.

Control devices of the present invention may have exceedingly high sensitivity and very high selectivity. With the use of an amplifier and two networks tuned to the same frequency in each circuit portion, as shown in the drawing, it is found that the controls to accomplish a given function are sensitive to signals in a wave-band having a width much less than 10 per cent of the signalfrequency and insenitive to signals outside this'bandy With the sharp cut-of! obtainable by the present invention, alarge number of signals to accomplish different functions maybe grouped relatively close together.

, It is to be understood that variations and modifications of the specific devices herein shown and described for purposes of illustration may be made without departing from the spirit Of the invention.

What I claim is: 1. A control or signal device adapted to be connected to an audio output portion of a radio recelver and responsive to a plurality of control frequencies to cause a plurality of functional Operations, comprising a plurality of circuit portions, each portion having connecting means for connection to a suitable power supply, a gridcontrolled electronic tube connected to said connecting means and adapted to pass plate current from said power supply or to substantially prevent current flow depending on the potential applied to the grid thereof, a relay operatively controlled by a change in said plate current, a filter means for selectively obtaining a higher potential at one of said control frequencies than for others, an amplifier connected to said filter means for increasing the potential at said control frequency, second filter means connected to the output circuit of said amplifier for separating the amplified potental at said control frequency, a rectifier connected to said second filter means for obtaining a rectified potential due to said amplified potential, means for delaying said rectie fled potential and means for impressin said rectified potential on the grid of an electronic tube in one of the other of said circuit portion-s, so that when said amplified potential in one of said circuit portions is of substantial magnitude 9. negative potential due to said rectified current is applied to said grid in another of said circuit portions, said filter means in one of said circuit portions being adapted to selectively obtain a potential at one of said control frequencies and the filter means in other Of said circuit portions being adapted to selectively obtain a potential at another of said control frequencies, so that in response to one control frequency flow of plate current in one of said circuit portions is sub-- stantially prevented and in response to another control frequency the fiow of plate current in the other of said circuit portions is substantially prevented, whereby said relays in said circuit portions are selectively operated in response to said control frequencies.

2. A control or signal device adapted to be connected to an audio output portion of a radio receiver and responsive to a plurality of control frequencies to cause a plurality of functional operations, comprising a plurality of circuit portions, each portion having connecting means for connection to a suitable power supply, a grid-controlled electronic tube connected to said connecting means and adapted to pass plate current from said power supply or to substantially prevent current flow, depending on the potential applied to the grid thereof, a relay operatively controlled by a change in said plate current, a circuit tuned to one of said control frequencies and connected through a resistance to an output portion of said receiver to obtain a potential drop at one of said control frequencies, an amplifier tube to amplify said potential drop, means for suitably connecting said tuned circuit to the grid of said amplifier tube, a second circuit tuned to substantially the same control frequency connected in series with the plate supply and the plate of said amplifier tube to obtain an amplifiedfpotential drop due to said amplified control fredue to said amplified potential drop", means for suitably connecting said second tuned circuit to said rectifier, means for smoothing out the waveform of said rectified current, and means for impressing a negative potential due to said rectified current on a control grid of said electronic tube in another of said circuit portions, said tuned circuits in different circuit portions being tuned to different control frequencies, so that in response to one control frequency flow of plate current in one of said circuit portions is substantially prevented and in response to another control frequency the flow of plate current in the other of said circuit portions is substantially prevented, whereby said relays in said circuit portions are selectively operated in response to said control frequencies.

3. In a control or signal device responsive to at least two control frequencies to cause at least two functional operations, two circuit portions, each portion having a source of power supply, a grid-controlled electronic tube adapted to pass plate current from said power supply or to substantially prevent current flow, depending on the potential applied to the grid thereof, a relay operatively controlled by said current, filter means for obtaining a potential drop at one of said control frequencies, an amplifier tube connected to said filter means for amplifying said potential, :1 rectifier connected to the output of said amplifier tube for obtaining a rectified potential corresponding to said amplified potential, means connected to said rectifier for filtering and delaying said rectified potential, and means for impressing a more negative portion of said rectified potential on a control grid of said electronic tube in another of said circuit portions, the filter means in each of said circuit portions being adapted to separate potential due to a different control frequency, so that in response to one control frequency fiow of the plate current in one of said circuit portions is substantially prevented and in response to another control frequency the flow of plate current in the other of said circuit portions is substantially prevented, whereby the relay of one of said circuit portions is operated in response to one of said control frequencies and the relay of said other circuit portion is operated in response to the other of said control frequencies.

, 4. In a control or signal device responsive to at least two control frequencies to cause at least two functional operations, two circuit portions, each portion having a source of power supply, a gridcontrolled electronic tube adapted to pass plate current from said power supply or to substantially prevent current flow, depending on the potential applied to a control grid thereof, a relay operatively controlled by said current, filter means for separating a potential drop at one of said control frequencies, a separate amplifier tube connected to said filter means for amplifying said separated potential, second filter means connected to said amplifier for obtaining said amplified potential from the amplifier output current, a rectifier connected to said amplifier for obtaining a rectified potential due to said amplified potential, means for filtering and delaying said rectified potential, and means for impressing a negative portion of said delayed rectified potential on the grid of said electronic tube in another of said circuit portions, the filter means in each of said circuit portions being adapted to separate potential at a different control frequency, so that in response to one control frequency flow of the plate current in one of said circuit portions is substantially prevented and in response to another control frequency the flow of plate current in the other of said circuit portions is substantially prevented, whereby the relay of one of said circuit portions is operated in response to one of said control frequencies and the relay of said other circuit portion is operated in response to the other of said control frequencies.

5. A control or signal device adapted to be connected to an audio output portion of a radio receiver and responsive to a plurality of control frequencies to cause a plurality of functional operations, comprising a plurality of circuit portions, each portion having connecting means for connection to a suitable power supply, a gridcontrolled electronic tube connected to said connecting means and adapted to pass plate current from said power supply or to substantially prevent current fiow, depending on the potential applied to a control grid thereof, a relay operatively controlled by a change in said plate current, a circuit tuned to one of said control frequencies and connected through a resistance to an output portion of said receiver to obtain a potential drop at one of said control frequencies, an amplifier tube to amplify said potential drop, means for suitably connecting said tuned circuit to the grid of said amplifier, a second circuit tuned to substantially the same control frequency connected in series with the plate supply and the plate of said amplifier tube to obtain an amplified potential drop due to said amplified control frequency, a rectifier to obtain a rectified current due to said amplified potential drop, means for suitably connecting said second tuned circuit to said rectifier, and means for applying a negative potential due to said rectified current to said control grid of said electronic tube in another of said circuit portions, said tuned circuit in different circuit portions being tuned to different control frequencies, so that in response to one control frequency flow of plate current in one of said circuit portions is substantially prevented and in response to another control frequency the flow of plate current in the other of said circuit portions is substantially prevented, whereby said relays in said circuit portions are selectively operated in response to said control frequencies.

6. In a control or signal device responsive to a control frequency with which a carrier is modulated to cause a functional operation, a receiver tuned to said carrier, a network connected to the output of said receiver and tuned substantially to said control frequency for separating a higher potential drop at said control frequency than at other frequencies an amplifier tube suitably connected to said network for amplifying said separated potential drop, a second network also tuned to substantially said control frequency and connected to the output of said amplifier for separating an amplified potential drop at said control frequency, a rectifyin means for obtaining a rectified current from said amplified and separated potential, means connected to said rectifying means for filtering and delaying build-up of potential from said rectified current, means for applying a portion of the delayed and rectified potential to a grid of an electronic tube which is connected to a suitable power supply to modify the plate current thereof, from said power supply, and a relay connected to the plate of said electronic tube to be controlled by said modification of said plate current, whereby the relay in said plate circuit is operated in response to said control frequency.

7. In a control or signal device responsive to a plurality of relatively low control frequencies with which a relatively high frequency carrier wave is modulated to accomplish a plurality of functional operations, a receiver tuned to said carrier, a circuit portion for each of said control frequencies connected into the output of said receiver, each portion comprising a connection to a source of power supply, a grid-controlled electronic tube adapted to normally pass plate current from said power supply but being adapted to prevent said plate current when said grid is made sufliciently negative, a network tuned substantially to one of said control frequencies for presenting a much higher potential drop at said control frequencies than at other frequencies, means for amplifyin said potential drop due to one of said control frequencies and separated by said network, a second network disposed in the output of said amplifying means and tuned to substantially the same frequency as said first-mentioned network for obtaining potential drop due to the amplified control frequency to which said networks are tuned, means for obtaining a rectified current from said amplified potential drop, means for suitably filtering said rectified current and means for delaying the build-up of a negative potential therefrom, means for applying said negative potential to said grid of said electronic tube in another of said circuit portions, which other circuit portion contains a network tuned substantially to another of said control frequencies, so that in response to one control frequency a negative charge is applied to the grid of said electronic tube in said other of said circuit portions to cause a decrease in plate current flow therethrough, and a relay suitably connected to the plate circuit of said last-mentioned electronic tube to operate by cessation of said plate current in response to one of said control frequencies.

GERALD G. ROBERTS.

REFERENCES CITED The following references are of record in the file of this patent:

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