US3047783A

US3047783A - Remote control arrangements

Info

Publication number: US3047783A
Application number: US749524A
Authority: US
Inventors: Johannes Franciscus Van Oort; Bakker Willem
Original assignee: US Philips Corp
Current assignee: US Philips Corp; North American Philips Co Inc
Priority date: 1957-08-27
Filing date: 1958-07-18
Publication date: 1962-07-31
Anticipated expiration: 1979-07-31

Description

July 31, 1962 .1. F. VAN OORT ET AL 3,047, 83

REMOTE CONTROL ARRANGEMENTS Filed July 18, 1958 3 Sheets-Sheet l g i o 8 1 4 113% 4 J L J/ h usl us I 9 10 INVENTORS JOHANNES FRANCISCUS VAN (DR! WILLEM BARKER July 31, 1962 J. F. VAN OORT ETAL 3,047,783

REMOTE CONTROL ARRANGEMENTS Filed July 18, 1958' 3 Sheets-Sheet 2 I l I INVENTOR JOHANNES FRANCISCUS VAN OORT WILLEM BAKKER BY 5W n. 30$.

AGE

July 31, 1962 J, VAN OORT ET 3,047,783

REMOTE CONTROL ARRANGEMENTS Filed July 18', 1958 3 Sheets-Sheet 3 Fl G5 10a so k f J OHANN ES FR 00R T WILLEM BAKKER BY a I 4 f. f

AGEN

United States The present invention relates to remote control arrangements. More particularly, the present invention relates to devices for carrying out at least one particular operation within a given space by means of apparatus electrically driven by wireless, for example for displacing and controlling apparatus adapted to :be driven by at least one electric motor or a part of apparatus comprising an electric motor.

Wireless control of relays or of measuring devices has been proposed in US. Patent No. 1,817,753 in which, however, the transmitted electrical energy is very small and in an inestimable ratio with regard to the energy supplied to the transmitter or with respect to the energy radiated by the antenna of the transmitter station. For a better transmission of energy use may be made of directional beam transmitter and receiver antennae, as proposed and set out in U.S. Patent No. 2,435,423 having for its object to supply electric motors by wireless. In this arrangement the supply of the motor is bound to a particular direction determined by the orientation of the antennae. When, for example, the receiver antenna is displaced by the motor, the transmission of energy ceases, unless the displacement occurs along the line along which the transmitted energy is concentrated by the transmitter antenna and the receiver antenna remains pointed towards the transmitter antenna. In this optimum case also, the efliciency of the transmission of energy varies substantially inversely proportionally to the square of the distance of the transmitter antenna from the receiver antenna, whereby regulation and control of the motor is seriously impeded.

The present invention has for its object to provide a device of the type set out in the preamble, and is based on the recognition that the use of any one of the modern ferromagnetic materials having a high permeability permits the transmission of energy by wireless with an appreciable and substantially invariable efi'iciency within a given space. The device according to the invention has the feature that it comprises a source of'alternating current, an exciter winding which is coupled to this source and defines said space and by which a magnetic alternating field isprcduced in said space. At least one open core of ferromagnetic material having a high permeability at the frequency of the alternating field, which core is so oriented relative to the exciter winding that an appreciable part of the magnetic flux produced by the mag netic alternating field concentrates therein. A feed winding is positioned on the core, in which winding an electric current for feeding the electrical apparatus is produced by the alternating magnetic ilux concentrated in the core. The open core is preferably tightly coupled to a selective electrical circuit tuned to a frequencysubstantia-lly corresponding to that of the alternating current.

Important uses of the invention are particularly in toys and model construction. .For example, toy cars, boats, trains and so on or similar vehicles of a trafiic model can thus be driven, controlled and so on Within a given space. A further possible use is the manipulation of expensive, sensitive unstable or dangerous materials, for example radio-active substances, within a given sometimes hermetically closed space.

atent nating current of a first example;

FIG. 2 is a diagram of a model of a toy fork-lift truck steered controlled and fed with electrical energy from said source;

FIG. 3 is a side-view of this fork-lift truck;

FIG. 4 is a ground plane;

FIG. 5 shows the wiring diagram of sources of alternating cur-rent of a second example;

FIG. 6 is a side view of exciter windings connected to said sources;

FIG. 7 shows a diagram of a model of a toy fire brigade motor vehiclefed, controlled and steered by said sources, and

FIG. -8 is a diagram of a model of an autocar used as a toy or as a component part of a trailic model of a third example.

The source of alternating current shown in FIG. 1 is a push-pull oscillator with two pentodes 1, 1' and an oscillatory circuit through which these valves are fed back; The anodes of the valves 1, 1' are fed from a supply 2, for example a direct current supply. One terminal of the supply source 2 is connected to the cathodes and to the third grids of the pentodes as well as to a tapping of a voltage divider 3 connected between the control grids of the tubes 1 and 1. The other terminal of the supply source 2 is connected to the centre tapping of a coil 4 of the oscillatory circuit. The coil 4 comprises four further :tappings, of which the two tappings remotest from the centre tapping are connected to the anodes of the valves, while the two other .tappings' are connected through coupling capacitors'6, 6 to the control grids of V the pentodes. The distribution of the several tappings' is such that the two pentodes are connected in push-pull with regard to the oscillatory circuit, while their control grids are coupled cross-wise to the common anode circuit through capacitors 6, 6'. The circuit of each control grid further comprises a series-

resistor

7 and 7 respectively which suppress any parasitic oscillations of the pentodes.

The screen grids of the pentodes 1, 1' are fed through resistors 8 and 8' respectively, for suppressing any parasitic oscillations through a variable resistor 9 and a makeand-break switch 10, from the positive terminal of the supply 2. The oscillatory circuit comprising the coil 4 further comprises a capacitor 11, a variable capacitor 12 and two further iixed capacitors 13, '14 adapted to be connected in and out of circuit by means of switches 15' and 16 respectively.

The coil 4 is made up of a small number of turns of a conductor of comparatively large diameter, for example 2 sq. mm., housed in a common and flexible envelope, junction conductors to the several tappings likewise entering this envelope. This permits the coil 4 constituting an excitcr winding to be given practically any desired form. For example, the exciter winding 4 may be laid on the ground so as to cover any desired part of the floor of a room. Alternatively, the winding may be arranged beneath a table leaf or around a container of non-conductive material which may be filled with water and in which model boats may be driven, steered and so on. The inductance variation produced by deformation of the winding 4 can be compensated by means of the variable capacitor 12 so that the frequency of the alternating current produced by the oscillator remains unchanged, for

example 50 kc./s. This frequency F can be reduced by means of

switches

15, 16, for example down to 30 and 20 kc./s. respectively (F and F respectively).

The apparatus adapted to be driven by means of the oscillator referred to is a toy model of a fork-lift truck. FIG. 3 is a side view of this fork-lift truck, and FIG. 4 is a ground plane of it; FIG. 2 shows its wiring diagram.

The fork-lift truck comprises a hoisting motor 20, a first driving motor 21 for one left hand wheel and another driving motor 22 for one right hand wheel. All the motors are small direct current motors of shunt type. They are fed with electric currentsinduced in windings on rods of a ferro-magnetic material having a high permeability, for example of a ferrite, such as ferroxcube 3B and even better ferroxcube 3A. The fork-lift truck carries four

bars

23, 24, 25 and 26 of ferrite so arranged as to extend substantially at right angles to the ground, hence also to the plane in which the exciter winding 4 extends. Each ferrite bar carries a first winding 27, 28, 29, 30 respectively which, together with

variable capacitors

31 and 32, 33, 34 respectively constitute a resonance circuit. Each resonance circuit is tuned to a given frequency. For example, the

circuit

27, 31 with core 23 is tuned to a fixed frequency of approximately 51 kc./s., the circuit 28, 32 with core 24 to a fixed frequency of approximately 49 kc./s., while the

circuit

29, 33 with core 25 is tuned to the fixed frequency F of 30 kc./s., and the

circuit

30, 34 with core 26 to the fixed frequency F of 20 kc./s. The bars 23 and' 24 carry another winding 35 and 36 respectively comprising a grounded center tapping point and connected to two

rectifiers

37 and 38, respectively, with

smoothing capacitors

37 and 38 respectively. An alternating current induced, for example in the winding 35 is rectified by rectifiers 37 and a direct voltage is supplied through relay contacts to the

motor

20 or 21. Similarly, a direct voltage from rectifier 38 may be supplied to either of the

motors

20 and 22. Both the Winding 28 and the

windings

29, 30 are grounded at one end and have a tapping for matching them to a load connected through rectifiers 39, 4t) and 41 respectively.

If the ferrite bars extend in the magnetic alternating field produced by the exciter winding this field, as a. resultof the high permeability of these cores, is concentrated in the latter. If the oscillator with the valves 1, 1 produces an alternating current of, for example, 30 kc./ s. the major part of the corresponding magnetic flux concentrates in the core 25 which is tightly coupled to 45 the

c1rcu1t

29, 33 tuned to the frequency of 30 kc./s.

The current haivng a frequency of 30 kc./ s. and induced in the

circuit

29, 33 produces a decrease in magnetic reluctance of the core 25 with regard to the magnetic alternating flux of 30 kc./s., so that this alternating field ooncen- 50 trates more strongly in the core 25 than it does" in the remaining

cores

23, 24, 26.

By means of the rectifier 40 the current induced in the

resonance circuit

29, 33 produces a direct current which via a switch 42, passes through the exciter winding 43 of 55 a relay 44. The exciter winding 43 is shunted by a capacitor 45 and, under the influence of the current through this winding, the contact 42 and four further contacts 46 to 49 are changed over so that the exciter winding 43 is then connected, via contact 42, to the rectifier 39 of the tuned circuit 28, 3 2. The

switches

15 and 16 of the oscillator with valves 1 and 1' should be closed only for a short time, subsequently to which the oscillator again produces alternating current having a frequency of approximately 50 kc./s. frequency induces an alternating current in the resonance circuit 28, 32, so that a direct voltage fed to the exciter winding 43 through rectifier 39 and contact 42 maintains, the relay 44 energized until the frequency of the oscillator is again changed.

On changing over the switches 46 to 49, the motor 20 instead of the

motors

21 and 22, is energized by the winding 35 with rectifiers 37 and by the winding 36 with rectifiers 38. The motor 20 actuates the lift-fork (FIGS. 3 and 4) of the fork truck. Its sense of rotation is variable The magnetic field having this 5 4. by changing over contacts to 53 of another relay 54 with two

exciter windings

55 and 56. The exciter winding 55 of this relay is shunted by a capacitor 57 and may be fed, through rectifier 41 by a current induced in the

circuit

30, 34 by a magnetic alternating field having a frequency 'of 20 kc./s. The exciter winding 56 is a hold-,

ing winding which, on changing over

contacts

51 and 53 is supplied in series with

motors

21 and 22 or with the motor 20, with the direct voltage produced by means of

rectifiers

37 and 38, provided the oscillator produces an alternating current having a frequency of approximately 50 kc./s. Like the capacitor 45, the capacitor 57 serves to hold the corresponding relay during the change-over time of the

corresponding holding contacts

42 and 51, 5-3 respectively. Since the motor 20 is supplied both with energy collected by the core 23 and with energy collected by the core 24, a resistor 58 is connected in series with this motor and with the holding winding 56. 7

With the

capacitors

13 and 14 connected out of circuit, the frequency of the alternating current produced by the oscillator with valves *1 and '1 is controllable between 49 kc./s. and 51 kc./s. If this frequency lies between the respective frequencies of the resonance circuits 27, 3 1

and 28, 32 respectively (in other words is equal to 50,

kc./s.) the energy supplied to the motor 21 is substantially equal to that fed to the motor 22, so that the two motors tend to run Well-nigh synchronously and the fork lift truck will follow a straight course. By shortly depressing the push button of the switch 16, an energy pulse having a frequency of 20 kc./s. is transmitted, so that the relay 54 becomes energized and that sense of rotation of the two

motors

21 and 22 is reversed with the result that the fork-lift truck runs backwards. If the relay 44 is energized, energization of the relay 54 brings about a reversal of the sense of rotation of the hoisting motor 20. The energy supplied to the

motors

21, 22 or to the motor 20 is variable by shifting the tapping of the variable resistor 9, so that the rate at which a load is lifted or lowered, alternatively the speed of the forklift tnlck is variable. A slight variation of the frequency of the produced alternating current 'by means of the variable capacitor 12 permits the energy supplied to the winding 35 of the core 23 and to the winding 36 of core 24" respectively to be changed, so that the motor 21 runs faster than the motor 22 or conversely. As a result, the fork-lift truck follows a bend to the left or to the right.

Small neon lamps

59 and 60 respectively are connected in parallel with the

resonance circuits

27, 31 and 28, 32 respectively. When the alternating voltage across one of these circuits increases the corresponding neon lamp ignites and consequently serves as a direction indicator.

The fork-lift truck is mounted on

wheels

62 and 63 driven from

motors

21 and 22 respectively, and on a third wheel 64 adapted to swivel freely and coupled toa steering-wheel 65. A dummy driver 66 on the fork-lift truck holds the steering wheel so that his arms follow the moxement of the wheel; the illusion is complete.

The speed control as well as the control of the speed of the hoisting motor 20 is simple and yet exact and smooth. Control of the forklift truck is easy and precise.

The generator is very simple and may, under circum- 70 hind and on the other side of the fork-lift truck. The two

smaller bars

25 and 26 are arranged one on each side of t the fork-lift truck, approximately halfway its length.

With a direct voltage of approximately 400 v. applied between the anode and the cathode of each of the valves 7 1 and '1, an alternating voltage power of approximately 50 w. was produced by the oscillator. The exciter winding 4 comprised 18 turns and covered a rectangular surface of one by two metres. The power supplied to the motors '21 and 22 was of the order of 1 w. This efficiency Valves 1. and 1' Pentodes type EL 34.

Resistor 3 2X47 kw.

Capacitors 6 and 6' 4700 pf.

Resistors

7 and 7 100 w.

Resistors '8 and 8 47 w.

Resistor 9 30 k Capacitor 11 2200 pf.

Capacitor 12 to 600 pf.

Capacitor :13 2200 pf.

Capacitor 14 9400 pt.

Bars

23 and 24 =-10 mms. length=150 mms.

Bars

25 and 26 =l0 mms. length=100 mms.

Windings 27 and 28---. About 6 00 turns per 30 mms.

length.

Windings 35 and 36 2. 3 turns.

Winding 29 About 800 turns.

Winding 30 About 950 turns.

Capacitors3 1 and =32--. About 500 pf.

Capacitor 33 About 900 pf.

Capacitor 34 About 1250 pf.

Resistor '58 100 w.

The second example illustrated in FIGURES 5, 6 and 7 comprises two alternating current generators and two exciter windings. The frequency of one of these generators assumes three different values; means being provided for modulating said frequency with a lower frequency, in a given setting. The apparatus is a model of a fire brigade motor vehicle comprising a ladder and a siren and capable of moving only in one direction and along a predetermined path. This path is determined by the exciter'winding of one of the generators feeding the driving motors of the vehicle. The other generator, the frequency of which can be changed and modulated, is coupled to an exciterwinding which is spaced from and arranged below the exciter winding of the first-mentioned generator. Each of these exciter windings is tightly coupled to the self-inductance of an oscillatory circuit of the corresponding generator. Due to their large size a considerable leakage occurs between the two exciter windings so as to avoid trouble from reaction of one oscillator on the other. v

The generator for feeding the driving motors comprises a pentode 71 and a resonance circuit'72 comprising an inductance with centre tapping through which the anode of the pentode 71 is supplied. This pentode and the resonance circuit 72 are connected as a three-point oscillator, the control grid of the pentode 71 being. coupled through a capacitor 73 to one end of the resonance circuit 72 and connected to the cathode through a resistor 74, while the anode is connected to the other end of the resonance circuit. ,The screen grid of the pentode 71 is fed through a variable resistor 75 decoupled by a capacitor 76 and through a make-and-break switch 77 The frequency of the alternating current produced by this generator is in principle fixed, and the variable capacitor of the resonance circuit 72 serves only to compensate any frequency variations resulting from deformation of the exciter winding 6 to be modulated. The cathode of this valve is grounded through a decoupled resistor 92, its screen grid being decoupled through a capacitor 93 and fed through a resistor 94. The third grid is connected to the cathode, while the control grid is connected to the anode through a resistor 95 and a blocking capacitor 96. This grid is also grounded through a large capacitor 97 and a comparatively small parallel capacitor 98. Hence, the control grid of the pentode 91 is controlled by the voltage at its anode through a phase-shifting network shifting this control voltage by approximately 90 in the opposite direction so that the pentode 91 connected in parallel with one half of the resonance circuit 82 of the second generator behaves 'as an inductance. The value of this inductance, and hence the frequency of the current produced by the second generator can be modulated by means of a signal generator comprising a triode 101 and a phase-shifting network through which positive feedback is produced. The anode of triode 101 is coupled to the control grid of pentode 91 through a capacitor 99 and can be med through a load resistor 100 and a switch 102 coupled to the switch 90. Its cathode is grounded through a decoupled resistor 103, while the phase-shifting network comprises three series capacitors 104 and three parallel resistors 105. The source of direct voltage for the two generators is decoupled by means of a capacitor 106.

An exciter winding 107 is tightly coupled to the reso- Q nance circuit of the second generator. As shown in FIG. 6,I the two

exciter windings

80 and 107 are provided one below the other, for example below a table-leaf 108. Certain parts of the exciter winding 80, along which the vehicle model takes sharp bends, are located further below the table top 108 to reduce the speed of the model in these bends. A portion'109 of the exciter winding 107 is laterally offset relative to the track of the model as determined by the exciter winding 80. Several electrical contacts 110 to 113 are provided on the table and along the track of the model to energize or deenergize two

relays

114 and 115. These relays control the switch 90 so that all the desired movements of the fire brigade vehicle follow each other automatically, since the vehicle closes the contacts 110 to 113 on its way.

The circuit arrangement of the vehicle is shown in FIG. 7. It comprises three bars of ferro-magnetic material, for example ferroxcube 3A, having a high permeability. Two of these bars extend at right angles to the plane of the track and consequently to the planes of the

exciter Windings

80, 107 and are provided one at each side at the front of the vehicle. Each of the bars and 121 respectively carries a

resonance circuit

122 and 123 respectively consisting of awinding and a variable capacitor and a second winding 124 and 125 respectively. Each of the

second windings

124 and 125 comprises a center tapping point and each is connected to

rectifiers

126, 127 respectively through which

motors

128 and 129 respectively are fed by the rectified current through the corresponding second winding. The bar 120 is arranged on the left-hand side and the corresponding motor 128 drives the left-hand front wheel, while the bar 121 is arranged on the righthand side and the corresponding motor 129 drives the right-hand front wheel of the vehicle. As a result of this set-up the vehicle follows the track determined by the excoupled to this resonance circuit. The second generator is in principle substantially identical to the first generator, except that the frequency of its resonance circuit 82 is adjustable to three difierent values by means of two

capacitors

88, 89 and a three-step switch 90. Moreover, the grid end of this resonance circuit is connected to the anode of a valve 91 which is connected as a variable reactance to permit the frequency of the second generator citer winding 80. For example, when the left-hand bar 120 comes above a portion of the winding 80, the magnetic alternating flux induced by this winding in this bar becomes substantiallyequal to zero, so that the motor 128 slows down or even stops when the bar 120 approaches a perpendicular part of the winding. As a result, the vehicle keeps moving in forward direction along the windmg.

The vehicle carries a third bar 130 of ferroxcube 3A, which'extends horizontally and transversely to the direction of motion of the vehicle, for example below the roof of the vehicle. Thisbar carries a resonance circuit 131 comprising a capacitor and a winding with a matching tapping and a second winding 132 comprising a centre tapping which is coupled to the tapping of the resonance circuit 131 through a capacitor 133. A capacitor 134 together with the second winding 132 constitutes a second resonance circuit which is connected to two rectifiers 135 together forming a discriminator circuit jointly with the resonance circuit 131, the

capacitors

133, 134 and a choke 136. The load of this discriminator circuit is a hoisting motor 137, the parallel exciter winding of which comprises a tapping connected to the centre of the outlet of the discriminator circuit. Two

capacitors

138, 139, d couplethe motor windings with regard to alternating current components of the demodulated voltage produced by the discriminator circuit. A small loudspeaker 141 is connected in parallel with the motor 137 and in series with a coupling capacitor 140.

So long as none of the

relays

114, 115 is energized the switch 90 remains in its mid-position, so that the signal generator with the triode 101 oscillates and produces a modulation frequency of, say 800 cycles. The second generator with the pentode -81 is modulated with this frequency of 800 cycles by means of the pentode 91, so that its frequency fluctuates about an average value of, say 30 kc./s. These frequency fluctuations involve corresponding voltage variations at the output of the discriminator,

whose

resonance circuits

131 and 132, 134 are tuned to the frequency of kc./ s. The windings of the direct current motor 137 have a comparatively high impedance with regard to the alternating voltage of 800 cycles produced at the output of the discriminator. This voltage is consequently supplied mainly to the loudspeaker 141 which produces a sound of approximately 800 cycles (siren).

If the vehicle moves, for example, in the direction of the arrow (FIG. 5) it first closes contact 110 so that the relay 114 becomes energized. The relay 114 holds itself energized through a holding contact 116 and

resistors

118, 119. As a result, the switch 90 is drawn to the left so that the frequency of the alternating current produced by the second generator is increased to, say, 32 kc./s. At the same time, the supply circuit of the anode of the triode 101 is interrupted so that the signal generator no longer oscillates and the frequency of the second generator is no longer modulated. Owing to the higher frequency of the magnetic alternating flux concentrated in the open core 139, a direct voltage is set up at the output of the discriminator, which voltage drives the motor 137 in a given direction. This motor then lowers a ladder mounted on the roof of the vehicle. This lowering occurs comparatively slowly, since the portion 109 of the exciter winding 107 is laterally olfset relative to the exciter winding 80 so that, as a result of the oblique orientation of the core 130 relative to the lines of force of the undisturbed field of the winding 107, a smaller part of the magnetic flux produced through the winding 107 concentrates in the bar 130. After the ladder has been lowered, the vehicle on its way closes the contact 111 with the result that the exciter winding of the relay 114 is short-circuited, so that this relay becomes de-energized and the switch 90 re-assumes its normal mid-position. Subsequently, the vehicle takes three sharp bends, while its speed is reduced due to the larger spacing of given parts of the winding 80, and the loudspeaker emits its signal. After the last of these three bends, the vehicle closes contact 112 so as to energize relay 115. This relay 115 holds itself energized through a contact 117 and

resistors

118, 119. The switch 90 then assumes its right-hand position, as a result of which the capacitor 89 is connected in the resonance circuit 82 of the oscillator, and the frequency of the alternating current produced by this oscillator is reduced, for example to 28 kc./s. The discriminator comprising

resonance circuits

131 and 132, 134 then produces a direct voltage of opposite polarity, so that the motor 137 starts running in the opposite direction and hoists the ladder. After the ladder has been completely hoisted, which occurs comparatively rapidly, the vehicle passes the contact g from the discriminator.

113 and the relay becomes de-energized. The switch 90 re-assumes its mid-position and the loudspeaker 141 emits a short warning signal until the vehicle again closes the first contact 110, and so on.

The frequency of the alternating current producedby the first generator with pentode 71 should naturally lie beyond the range of the discriminator with resonance 'cir-..

already described. The autocar model carries two

ferroxcube bars

142, 143, extending at right angles to the plane of the track and widely spaced from each other. Each of these ferroxcube bars carries two windings with tappings which, together with capacitors, rectifiers and a choke,

constitute discriminators as described with reference to FIG. 7. The discriminator, the windings of which are arranged'on the bar 142, is tuned to a first frequency of, say, 50 kc./s. and its load circuit is constituted by the windings of a driving motor 144 driving for example, the

two rear wheels of the vehicle through a differential. The.

discriminator, the windings of which are arranged on the bar 143, is tuned to a second frequency of, say 30 kc./s.

by means of two variable capacitors and 146. These capacitors are mechanically coupled together and, moreover, mechanically coupled to a control motor 147 fed The generator for driving and steering the vehicle comprises two oscillators, for example, corresponding to those shown in FIG. 1, which are coupled to two exciter windings. The first generator or driving generator is adapted to oscillate on two different frequencies. Normally, it oscillates at a frequency of say 52 kc./s., the discriminator coupled to the bar 142 producing a direct voltage of such polarity that the motor 144 drives the vehicle in forward direction. When varying the frequency of this first generator, for example to 48 kc./s. by adding an additional capacitor to its resonance circuit, the polarity of the direct voltage supplied to the motor 144 is changed, so that the vehicle rides backwards. The speed at which the vehicle moves is accurately variable by means of a variable resistor, for example the resistor 9 shown in FIG. 1.

A second generator oscillates at a variable frequency of, say, 28 kc./s. to 32 kc. /s., which can be varied by means of a variable capacitor, for example the capacitor 12 shown in FIG. 1. If the frequency of this oscillator exactly corresponds to the frequency on which the discriminator of the bar 143 is tuned, this discriminator does not produce any direct voltage and the control motor 147 stands still. If the frequency is changed, the discriminator produces a direct voltage of either polarity and the control motor revolves until as a result of variation of the capacities of the

capacitors

145 and 146, it has tuned the discriminator to the frequency of the alternating current produced by the second generator.

A wide diversity of modifications of the steering and control devices are of course possible and the examples given only convey an idea of what is obtainable by simple means. Of course, amplitude modulation of one or the other of the produced alternating currents might be rethe help of which useful driving-lessons can be given, in

particular as regards trafiic rules. Naturally, the generators of the toy-car entrusted to the pupil may be constructed so that its different control functions are accom-.

that of a real automobile.

Other uses of the arrangements of the present invention I are in the field of games of skill. For example, if two or more toy cars are driven on the same course, within the range of corresponding exciter windings, collision may easily be provoked or on the contrary thereto, collision may be made very difficult. If, for example these toy cars are driven and steered according to the system described with reference to FIGURES 1 to 4, and if in each vehicle the bar for driving theright-hand wheel is disposed right in front and that for driving the left-hand wheel is disposed behind, collision is difficult to occasion. When the two vehicles approach each other, reaction between the front bars occurs; due to the approaching other bar the resonance circuits of the two bars are slightly detuned with respect to the frequency of their respective generators so that the right-hand wheel of each vehicle is driven more slowly and each vehicle takes a turn to the right, thus avoiding the other vehicle. If, on the contrary,. the right-hand wheel of oneof the vehicles is driven by energy collected by its front bar, and the left-hand wheel of the other vehicle is driven by energy collected by the front bar of the second vehicle, the first-mentioned vehicle takes a turn to the right when approaching the second whereas the second vehicle takes a turn to the left, so that the chance of collision is considerable.

What is claimed is: t

1. A remote control arrangement for actuating electrical apparatus within a control area comprising an exciter winding arranged to define said control area within which said apparatus is actuated, a source of alternating current coupled to said exciter winding in a manner whereby an alternating magnetic flux is produced by the said exciter winding, said magnetic flux having a predetermined frequency, an open core of ferromagnetic material having a high permeability at the frequency of said magnetic flux, means mounting said core on said apparatus in a manner whereby a substantial portion of said magnetic flux concentrates in the said core, and means for energizing said electrical apparatus comprising a winding on said core and means coupling said last-mentioned winding to the said apparatus.

. 2. A remote control arrangement for actuating electrical apparatus comprising an exciter winding arranged to define a control area within which said apparatus is actuated, a source of alternating current coupled to said exciter winding in a manner whereby an alternating magnetic flux is produced by the said exciter winding, said magnetic flux having a predetermined frequency, an open .core of magnetic ferrite material having a high permeability at the frequency of said magnetic flux, means mounting said core on said apparatus in a manner whereby a substantial portion of said magnetic flux concentrates in the said core, electrical control apparatus mounted on said first-mentioned apparatus, and means for energizing said control apparatus comprising a winding on said core and means coupling said last-mentioned winding to the said control apparatus.

3. A remote control arrangement for actuating electrical apparatus comprising an exciter winding arranged to define a control area within which said apparatus is actuated, a source of alternating current coupled to said ex citer winding in a manner whereby an alternating magnetic flux is produced by the said exciter winding, said magnetic flux having a predetermined frequency, an open core of ferromagnetic material having a high permeability at the frequency of'said magnetic flux, means mounting said core on said apparatus in a manner whereby a substantial portion of said magnetic flux concentrates in the said core, a selective circuit tuned to substantially the frequency of said alternating current, said selective circuit being tightly coupled to said core, electrical control appa ratus mounted on said first-mentioned apparatus, and means for energizing said control apparatus comprising a winding on said core and means coupling said last-mentioned winding to the said control apparatus.

4. A remote control arrangement for actuating electrical apparatus comprising an exciter winding arranged to define a control area within which said apparatus is actuated, a source of alternating current coupled to said exciter winding in a manner whereby an alternating magnetic flux is produced by the said exciter winding, means for varying the frequency of said alternating current, said magnetic fluxhaving corresponding frequencies, an open core of ferromagnetic material having a high permeability at the frequency of said magnetic flux, means mounting said core on said apparatus in a manner whereby a substantial portion of said magnetic flux concentrates in the said core, a selective circuit tuned to a predetermined fre quency within the frequency range of said alternating current, said selective circuit being tightly coupled to said core, electrical control apparatus mounted on said firstmentioned apparatus, and means for energizing said control apparatus comprising a winding on said core and means coupling said last-mentioned winding to the said control apparatus thereby providing a control current having an amplitude which varies when the frequency of said alternating current varies.

5. A remote control arrangement for actuating electrical apparatus comprising a source of alternating current, a resonant circuit coupled to said source of alternating'current to determine the frequency of said alternating current, an exciter winding arranged to define a control area for said apparatus, means coupling said exciter winding to said resonant circuit in a manner whereby an alternating magnetic flux having a corresponding frequency is produced by the said exciter winding, said last-mentioned coupling means comprising a transformer having a primary winding connected in said resonant circuit and a secondary winding having a relatively low impedance connected to said exciter winding, an open core of ferromagnetic material having a high permeability at the frequency of said magnetic flux, means mounting said core on said apparatus in a manner whereby a substantial portion of said magnetic flux concentrates in the said core, electrical control apparatus mounted on said first-mentioned apparatus, and means for energizing said control apparatus comprising a Winding on said core and means coupling said last-mentioned winding to the said control apparatus.

6. A remote control arrangement for actuating electrical apparatus comprising an exciter winding arranged to define a control area within which said apparatus is actuated, a source of alternating current coupled to said exciter winding in a manner whereby an alternating magnetic flux is produced by the said exciter Winding, said magnetic flux having a predetermined frequency, means for varying the amplitude of said alternating current, an open core of ferromagnetic material having a high permeability at the frequency of said magnetic flux, means mounting said core on said apparatus in a manner whereby a substantial portion of said magnetic flux concentrates in the said core, electrical control apparatus mounted on said first-mentioned apparatus, and means for energizing said control apparatus comprising a winding on said core and means coupling said last-mentioned winding to the said control apparatus.

7. A remote control arrangement for actuating electrical apparatus comprising first and second exciter windings arranged to define a control path for said apparatus on a predetermined surface, first and second sources of alternating current each producing a frequency difierent from that of the other, means coupling said first source of alternating current to said first exciter Winding in a manner whereby an alternating magnetic flux is produced in the said first exciter winding, means coupling said second source of alternating current to said second exciter winding in a manner whereby an alternating magnetic flux is produced in the said second exciter winding, each 11 said magnetic flux having a different predetermined frequency, an open core of ferromagnetic material having ahigh permeability at the frequency of a magnetic flux, means mounting said core on said apparatus in a manner whereby a substantial portion of said magnetic flux concentrates in the said core, a selective circuit tuned to substantially the frequency of an alternating current, said selective circuit being tightly coupled to said core, electrical control apparatus mounted on said first-mentioned apparatus, means for energizing said control apparatus 1 comprising a winding on said core and means coupling said last-mentioned winding to the said control apparatus,

and means for positioning said first and second exciter windings from each other and from said first-mentioned 5. tive to said magnetic flux varies in a predetermined pattern.

References Cited in the file of this patent UNITED STATES PATENTS Bourget et a1 Mar, 29, 1960