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| United States Patent | 3,881,310 |
| Gerum , et al. | May 6, 1975 |
Clock adapted to be synchronized by alternating current in a wireless
manner
Abstract
An electric clock having an electromagnetically operated mechanical oscillator with actuating coil means and a magnet on the mechanical oscillator cooperating with said coil means. The natural frequency of the electromagnetical oscillator is double the rated frequency of an alternating current network. A transmitter connected to the network transmits a carrier wave at a supersonic frequency which is modulated by the network at double the network frequency. A receiver at the clock receives and demodulates the carrier wave and supplies the pulses to the coil of the mechanical oscillator. An electrical oscillating circuit at the clock is connected to the coil of the mechanical oscillator and a control arrangement disables the electric oscillator when the pulses derived from the carrier wave coincide in frequency with the natural frequency of the mechanical oscillator by enabling the electric oscillator when the network frequency departs a predetermined amount from the natural frequency of the mechanical oscillator.
| Inventors: | Gerum; Erich (Nuremberg, DT), Meisner; Alfred (Nuremberg, DT) |
| Assignee: |
Diehl
(Nuremberg,
DT)
|
| Appl. No.: | 05/379,563 |
| Filed: | July 16, 1973 |
| Mar 02, 1971 [DT] | 2109707 | |||
| Mar 02, 1971 [DT] | 2109705 | |||
| Current U.S. Class: | 368/47 ; 368/52; 968/490; 968/510 |
| Current International Class: | G04C 11/00 (20060101); G04C 3/00 (20060101); G04C 11/02 (20060101); G04C 3/14 (20060101); G04b 001/00 () |
| Field of Search: | 58/35W,33,24R,23R,23A,23BA,23AC 318/16 |
| 3169218 | February 1965 | Reich |
| 3643420 | February 1972 | Haydon |
| 3756010 | September 1973 | Kimura et al. |
Assistant Examiner: Weldon; J.
Attorney, Agent or Firm:
This is a continuation-in-part application of co-pending Ser. No. 230,326 -- Gerum et al. filed Feb. 29, 1972 and belonging to the assigne of the present invention.
What is claimed is:
1. In combination with an electric clock and a transmitter, said clock having therein an electromagnetically operated mechanical oscillator with a predetermined natural frequency which is a selected whole number times the rated frequency of an alternating current network, said electromagnetically operated mechanical oscillator including actuating coil means therein, said transmitter that generates a carrier wave being installed at a location remote from the electric clock wherein said mechanical oscillator is provided, aerial means respectively being provided for effective relationship between said transmitter and said clock, modulating means in the transmitter, said transmitter being adapted to be connected to said network and including means operable to transmit said carrier wave at a higher frequency greater than that of audible sound and modulated by said modulating means effective with said network at a lower frequency which is said selected whole number times the frequency of the network, a receiver at the clock having an input end and an output end, a demodulating means in the receiver, said receiver being adapted to receive said modulated carrier wave at said input end and including amplifier means operable to amplify and connected serially with said demodulating means to demodulate the wave to develop first pulses at said lower frequency at said output end, means connecting said output end of said receiver to said coil means to supply said first pulses thereto, a battery powered electric oscillator at said clock developing second pulses at said natural frequency of said mechanical oscillator and connected to said coil means, semi-conductor control means in circuit between said electric oscillator and said coil means normally disabling said electric oscillator, means lying between said coil means and said electric oscillator sensitive to the supply of an impulse signal in response to deviation of frequency of the network by a predetermined amount from the rated frequency thereof to enable said electric oscillator to operate, and comparing means comparing the frequency of said first pulses to the said natural frequency of said mechanical oscillator connected therewith and connected to supply a said impulse signal to said semi-conductor control means in response to deviation of said network frequency by a predetermined amount from the said rated frequency thereof, said receiver at the output end including a first transistor having the emitter-collector path in series with said actuating coil means and the base connected to receive said first pulses; said electric oscillator comprising a second transistor having the emitter-collector path in series with a portion of said actuating coil means and said battery; said semi-conductor control means comprising a third transistor having the remainder of said actuating coil means connected between the base and the emitter thereof, the collector of said third transistor being connected to the base of said second transistor and via a capacitor to the emitter of said third transistor and via a resistor to one side of said battery, said mechanical oscillator having magnet means linking said remainder of said actuating coil means to develop pulses therein during oscillation of the mechanical oscillator.
2. A clock in combination according to claim 1 in which said transmitter comprises full wave rectifier means connected to the network and supplying modulating pulses to said carrier wave of said transmitter at double the frequency of said network.
3. A clock in combination according to claim 1 in which the frequency of said carrier wave is within the range of from about 20 kilocycles per second up to about 50 kilocycles per second.
4. A clock in combination according to claim 1 in which said receiver comprises a filter means including RC elements connected between said amplifier means and said demodulating means.
5. A clock in combination according to claim 4 in which the RC elements in said filter means are so dimensioned as to obtain maximum damping at carrier wave frequency.
6. A clock in combination according to claim 1 in which said transmitter and receiver comprise aerials for the respective transmission and receiving of the modulated carrier wave.
7. A clock in combination according to claim 6 in which said aerials are arranged vertically.
8. A clock in combination according to claim 2 in which said transmitter includes current controlling means in circuit with output location of said rectifier means.
9. A clock in combination according to claim 8 in which said current controlling means is in series with outlet location of said rectifier means.
10. A clock in combination according to claim 8 in which said current controlling means is in the form of a glow lamp having an ignition voltage which is about half of the normal network voltage.
11. A clock in combination according to claim 8 in which said current controlling means is in the form of Zener diodes arranged in branches of the rectifier means.
12. A clock in combination according to claim 1, in which said means sensitive to the supply of the impulse signal thereto to enable operation of said electric oscillator and said comparing means comprise a loosely-coupled pulse comaring circuit receiving pulse sequence to be compared with network frequency, and electrical mechanical pulse generator having a mechanical resonator means in resonance with the synchronizing pulses, the signals in said receiver after amplification and demodulation being conveyed to said pulse comparing circuit, during resonance condition there being energy supplied for maintaining oscillation thereof and for synchronous drive of a driving mechanism for an indicator from an amplified input signal of said receiver, and an electro-mechanical pulse generator means which disengages itself from the synchronizing pulses and which alone takes over the timewise proper control of the driving mechanism when the network frequency deviates from the rated frequency by at least partial fractional amount up to and including complete failure of network frequency.
The present invention relates to a clock which is adapted to be synchronized by low frequency network current, the driving mechanism of which is actuated by a battery built into the clock, and if desired, through an amplified circuit.
Clocks have become known in which a synchronous motor is employed for driving the indicating mechanism, which motor is driven in synchronism to the network frequency while being directly connected to the alternating current network.
Also, clocks have become known which are in direct conductive connection with a master clock, which latter gives off synchronizing pulses for keeping the other clocks in synchronism. The present invention, however, does not relate to clocks of the above mentioned type which require an electric line connection for supplying the current or for controlling the clocks. It is rather an object of the invention to provide synchronizable clocks which are independent of a master clock and which do not require a line connection so that they are no longer bound to a specific location.
Also, clocks have become known which are synchronizable in a wireless manner and which are synchronized by a radio transmitter which as time standards emits pulse-shaped signals, for instance, in sequences of seconds. In the receiver, the time giving pulse sequence received from the emitter is in a comparator containing two NAND gate circuits compared with a second pulse sequence which is furnished by an oscillator of the clock. When the deviation between the two pulse sequences to be compared with each other exceeds a previously fixed value, the comparator furnishes signals to a correcting device which so influences the pulsing sequence generated in the clock that the error in the deviation is again compensated for. To this end, additional logical circuits with AND and OR gate circuits and a control circuit are employed which prevents a correction of the pulse sequence generated in the receiver, when transmitting disturbances have occurred between the transmitter and the receiver. However, not only are such radio transmitters and the master clocks employed for generating the time standard of rather complicated construction and therefore liable to disorders and expensive, but also with the other clocks which are to be synchronized by the radio signal, relatively considerable technical equipment is necessary in order to neutralize or eliminate possible atmospheric disturbances. In addition thereto, it may also be mentioned that from case to case in conformity with the geographic location of the receiver, the signals coming from the radio transmitter can be received only poorly. When, for reasons of cost, such additional technical equipment is not admissible and when the synchronizable clocks are to be employed in public offices, factories, private offices and dwellings, other means have been resorted to. More specifically, the fact that the frequency of the customary alternating current network, at least when considered over a longer period of time, has a high constancy has been taken advantage of for synchronizing clocks. To this end, the low frequency electric or magnetic alternating fields which forms in the form of a stray field in the vicinity of conductors connected to the network have been received by means of an aerial, and the signal after having been amplified has been used directly for driving or synchronizing the driving mechanism of the clock, which driving mechanism is actuated by a power source built into the clock. Although these clocks are no longer bound to a certain place, they have the drawback that the magnetic alternating field is totally absent when no consumers are connected to the network, which means if no current flows in these conductors. The then still present electric stray field is frequently extremely weak and can be received only by high sensitive and, in most instances, direction depending aerials and can be employed only with multi-stage amplifiers.
Aside from the fact that in view of the frequently employed dischargers or by the increasing employment of controlled semiconductors, no precise maxima or minima occur at the receiving station, the building up of a suitable receiver still encounters the following difficulties. In order to cope with the network stray field, an amplifier with extreme high ohm input and high amplifying factor has to be employed because the receiving voltage considerably drops already at a distance of a few meters from the network conductors. With the increase in the input resistance, however, not only the alternating field sensitivity increases, but also the sensitivity with regard to static fields and other disturbing signals. The employed synthetic materials of various types which are employed to an ever increasing extend have in part high insulating properties and therefore can easily take high static charges so that it is meaningless to increase the sensitivity of the receiver still further. Relationship between usefulness and disturbances can in this way not be improved.
It is, therefore, the primary object of this invention to provide a clock which is adapted to be synchronized in a wireless manner while avoiding the above mentioned drawbacks.
It is another object of this invention to provide a clock as set forth in the preceding paragraph which makes use of the advantages inherent to the stabile frequency of the alternating current network which remains substantially uninfluenced by outside disturbances and which, in spite of few technical means, will even with undesirably high deviations of the network frequency and with a complete failure of the network be operated further at high precision.
These objects and other obbjects and advantages of the invention will appear more clearly from the following specification, in connection with the accompanying drawings, in which:
FIG. 1 shows a block circuit according to which a transmitter is connected to a low frequency alternating current network.
FIG. 2, by means of a block circuit, illustrates the buildup of the receiver.
FIG. 3 represents a circuit for the pulse comparison.
FIG. 4 represents a diagram for showing the course of the voltage with the heretofore customary rectification.
FIG. 5 shows the course of the voltage which is realized by a further development of the invention with regard to the transmitter circuit.
FIG. 6 diagrammatically illustrates the electric circuit of the transmitter.
FIG. 7 shows circuitry to illustrate a feed-back loop with features usuable for the present invention.
The objects of the present invention have, with a clock of the above mentioned type which is to be synchronized in a wireless manner, been solved by the fact that a transmitter is connected to the alternating current network, which transmitter generates a magnetic and/or electric alternating field with a frequency which is above the sound frequency which latter is modulated directly by low frequency synchronizing signals derived from the network or is modulated with a multiple of such low frequency synchronizing signals. The invention is furthermore characterized in that the signals in the receiver are after amplification and demodulation conveyed to a loosely coupled pulse comparing circuit. This pulse comparing circuit receives the pulse sequence to be compared with the network frequency from an electromechanical pulse generator. The mechanical resonator of said pulse generator is in resonance with the synchronizing pulses and in this condition from the amplified input signal of the receiver receives the energy for maintaining its oscillation and for the synchronous drive of the driving mechanism. The electromechanical pulse generator disconnects itself each time from the synchronizing pulses and alone takes over the timely control of the driving mechanism, when the low frequency deviates by a determinable fraction from the rated frequency or when the network frequency drops out completely.
It has been found particularly advantageous when the mechanical resonator which is employed in the receiver as pulse emitter has a frequency of 100 cycles per second. In such an instance, the frequency of the synchronizing pulses can in a simple manner be obtained from the network by means of a rectifier bridge which doubles the network frequency. The 100 cycles per second impulse sequence is modulated with the carrier frequency and conveyed to the transmitter aerial. The frequency of the transmitter should expediently amount to 20 and 50 kilocycles per second in order that on one hand it will be sufficiently far from the audible range and on the other hand will be sufficiently low in order to keep away from the range of influence the fundamental waves and first harmonic vibrations from television transformers.
There has, however, been found that in view of the unavoidable capacitive influences in the transmitter circuit, especially in view of the amplifier capacity, the pulse lengths do not fully become zero so that the minima received by the receiver are not very strong. Therefore, it is a further object of this invention to provide a transmitter which, while taking advantage of both sine half waves of the useful alternating voltage as synchronizing pulses between the individual pulses has sufficiently great keying space so that the transmitting frequency at these points in its amplitude approximately reaches the value zero.
This further object has been realized by the fact that the network alternating voltage which is doubled as to its frequency by means of a rectifier bridge is for purposes of modulation conveyed with the carrier frequency to the transmitter through one or more electric control means which allow the current to pass through only when a voltage threshold value has been obtained.
In order to keep the technical equipment for the transmitter to a minimum, as control element exediently a simple glow lamp is employed, the ignition voltage of which advantageously is above half the network voltage. The same effect may also be realized by employing instead of the glow lamp, Zener diodes which in at least two branches of the rectifier bridge are operated within their Zener range, which Zener diodes likewise have a pronounced breakdown voltage.
Referring now to the drawings in detail, the low frequency alternating current network is designated with the reference numeral 1, the frequency of which in all industrialized countries, when considering a longer period of time, has a very satisfactory constancy which is adapted at satisfactory precision to be used as time standard for synchronizing clocks. In the impulse emitter 2 the alternating voltage of the network is rectified by means of a bridge rectifier whereby pulses with the double network frequency are obtained. These pulses are modulated in the modulator 3 at carrier frequency which expediently has a value of from 20 to 50 kilocycles per second. In the described embodiment, it is assumed that the transmitter frequency starts at 25 kilocycles per second. The thus modulated pulses are conveyed to the transmitter coil of the or antenna 4 which expediently is designed as vertically arranged wave magnet and for the purpose of the present invention has favorable propagation properties. In order to keep the current consumption and the heat development as low as possible, electronic elements including transistor diodes and Zener diodes as noted subsequently herein are employed in the transmitter and receiver circuit. In this way, so small dimensions of the transmitter are obtained that the transmitter finds sufficient place in a housing which as to size and shape corresponds to approximately a telephone plug. In order when connecting the transmitter not to lose the useful effect of the jack, the customary sockets for other devices to be connected to the network may be arranged on the sides of the housing. In the wave magnet, first of all, the magnetic stray field is taken advantage of whereby the range of the transmitter can be better limited and whereby also undesired over-the-horizon ranges can be eliminated which would otherwise interfere in more remote surroundings.
The receiver according to FIG. 2 likewise comprises vertically arranged aerials of the wave magnet type, which conveys the magnetic and/or electric field to the amplifier 6, amplifier 6 being built up of a plurality of transistorized amplifier stages. In a feed-back branch of the amplifier there is arranged a filter 7 composed of RC-elements, for instance a double T filter, the structural elements of which are so dimensioned that the maximum damping of the filter will occur at the carrier frequency. In this way, the selectivity of the or antenna 5 is increased and interferences which may originate for instance from a 50 cycle per second interference field are suppressed. Behind the demodulator 8 the desired synchronizing pulses are received which correspond to the double network frequency.
All parts of the receiver shown in FIG. 2 including the aerial 5 can in view of their small size be arranged in a customary clock housing. Such housing also contains the pulse generator 9 which comprises primarily a mechanical resonator, the oscillation frequency of which is tuned to the frequency of the newtwork. The electric receiver circuit, the driving mechanism 11 for the indicator 12 and the pulse generator 9 are all driven by a battery in the clock. The pulse frequency generated in the pulse generator 9 and kept constant by the mechanical resonator is compared to the frequency of the synchronizing pulses in the pulse comparing circuit 10 which frequency is received by the transmitter.
FIG. 3 shows by way of a diagram, details of the pulse comparing circuit 10 according to FIG. 2. At the base of the input transistor 20 there prevails the synchronizing signal of the network in the form of comparatively short pulses so that the transistor 20 will at a pulse frequency of 100 cycles per second be conductive for a short time, said synchronizing signal having been received by the transmitter and having been prepared in the receiver circuit. With a coil 21 which is equipped with a tapping and which in its entirety acts as a synchronizing coil, one coil section 21a serves as driving coil whereas the other coil section 21b serves as control coil for mechanical resonator 22. The transistor 20 drives at a 100 cycle per second oscillation and through coil 21 the mechanical oscillator which is preferably formed by a tuning fork. By means of a non-illustrated magnetic coupling, the wheel 23 is uniformly rotated synchronously with regard to the oscillating frequency of the resonator 22 whereby the driving mechanism 11 of the indicator 12 is driven. Coil 21 is preferably energized by the synchronizing pulses when the tuning fork 22 oscillates through the zero point. It is known that for maintaining this oscillation, as long as oscillating synchronism prevails between the drive and the mechanical resonator, only an extremely small quantity of energy is required. To the end of the tuning fork 22 there is connected a small permanent magnet 22a which in view of its oscillation induces a small electromotoric force in the coil 21. If now, the frequency of the pulses received from the network differs from the frequency of the tuning fork 22, also the oscillation of the tuning fork is no longer completely in resonance with the driving pulses. As a result thereof, the energy of the synchronizing pulses will no longer suffice for completely maintaining the oscillation of the tuning fork 22. It is at this point that with increasing deviation of the frequencies, the pulses of the working transistor 24 start to an ever increasing extent. The working transistor is in the case of synchronism, which means when the synchronizing pulses occur at the right time with regard to the oscillation of the tuning fork 22. It is at this point that with increasing deviation of the frequencies, the pulses of the working transistor 24 start to an ever increasing extent. The working transistor is in the case of synchronism, which means when the synchronizing pulses occur at the right time with regard to the oscillation of the tuning fork, blocked by the effect of the control transistor 25. The control transistor 25 which has its base connected to the voltage divider 26, 27 furthermore brings about that the amplitude of the working pulses is kept constant. These working pulses pass only to the winding of the driving coil 21a. When the electromotoric force generated in the control coil 21b increases, the control transistor 25 becomes conductive to greater extent whereby the condenser 29 is short circuited. Inasmuch as the coil sections 21a and 21b are coupled to each other , a condenser 30 is interposed between the base and the collector of the transistor 24 whereby the circuit will be prevented from working as a blocking oscillator. When the frequency of the synchronizing pulses obtained from the network differ considerably from the frequency of the tuning fork 22, and if the network fails completely, the pulses for driving the tuning fork 22 are generated by triggering the working transistor 24 which pulses through driving coil section 21a go to minus. In this connection, first the base of the transistor 24 is biased by the resistor 28 whereby a small current flows through the emitter junction and the driving coil section 21a. The electromotoric force induced in the control coil 21b by the oscillation of the permanent magnet 22a passes through the condenser 29 to the base of the transistor 24 whereby the transistor is somewhat more modulated and causes a somewhat stronger pulse to pass to the driving coil section 21a. This is repeated several times in a very short time until the full electromotoric force is obtained for maintaining the oscillation of the tuning fork 22.
As long as the network frequency is identical to the frequency of the pulse generator, the mechanical resonator and the driving mechanism for the clock are driven for all practical purposes only by the amplified input pulses of the receiver. If, however, the frequency of the network 1 differs from the frequency of the pulse emitter 9 beyond a permissible tolerance, which tolerance may be set for instance for .+-. 0.15 cycles per second, the pulse generator 9 of the receiver will at a frequency which is held constant by the mechanical resonator, at increasing frequency difference and with the electromotoric force remaining constant take over the drive of the resonator and thereby of the clock. This desired effect which corresponds to a loose coupling of the pulse frequency generated by the pulse generator with the synchronizing frequency received from the network in the receiver is obtained by the fact that the mechanical resonator relative to the received synchronizing pulses has a relatively high oscillation stability. Moreover, the mechanical resonator has a highly integrating effect whereby almost all interfering pulses are absorbed. In order to keep the current consumption of the coil for the drive of the mechanical resonator and of the driving mechanism as low as possible, the pulse generator circuit is so designed that the coil for driving the mechanical resonator is at least partially employed for synchronizing the comparing pulses. Also, when the network fails, the driving mechanism continues operating at its own frequency which in view of the mechanical oscillator is so constant that a deviation of the clock from the rated value will also over a longer period of time remain within a permissible range.
As will be seen from FIG. 4, from the network alternating voltage when employing a rectifying bridge, both half waves of the sine oscillation are made use of so that the rectified pulse sequence will have the double network frequency. The transmitter circuit, especially the rectifier bridge has a capacitive influence upon the shape of the pulse form which differs or deviates from the ideal shape which is indicated by dash lines at 31. It will be evident therefrom that the voltage value between the individual half waves does not drop to zero so that also the carrier frequency at these points does not have a clear and usuable minimum. As a reuslt thereof, a reliable working of the receiver is not assured in every respect for the precise time keeping of the clock which is synchronizable in a wireless manner, it would be desirable that at the receiver there were available a sufficiently wide key gap.
The curve of the transmitter pulses as obtained by the present invention is shown in FIG. 5. According to FIG. 5, between the pulses a sufficiently wide keying space 32 is formed by the application of an electric control element which becomes current conductive only when a certain voltage swell value has been obtained, the amplitude of said keying space 32 equals or approximately equals zero.
FIG. 6 shows the electric circuit of the transmitter according to the invention. The transmitter 33 which is known per se generates a carrier frequency of for instance 25 kilocycles per second which is conveyed to a wave magnet 34. Connected to the alternating current network is a rectifier bridge 35, at the outlet of which prevails the voltage of the two rectified network sine half waves. This pulse sequence has a frequency which equals twice the frequency of the network. Between the rectifier bridge 35 and a tapping of the transmitter coil 34 there is arranged an electric control element 36 which will let the current pass only when a certain voltage swell value has been reached. According to the embodiment illustrated in FIG. 6, this control element is represented by a simple glow lamp 36. Expediently, the voltage of the glow lamp 36 is so selected that it is somewhat above the voltage of the network. With these dimensions, a sufficiently wide key gap 32 (FIG. 5) is obtained without affecting the energy content of the pulse. The same effect can also be realized when instead of the glow lamp 36 Zener diodes 27 are provided in two branches of the rectifier bridge in addition to the already present rectifier diodes. This has to be effected in such a way that when viewed in the forward direction of the rectifier diodes the Zener diodes are operated in their Zener range.
By means of this simple step it is possible to modulate the transmitter in the pulse intervals to zero so that also at short distances between transmitter and receiver a pulse gap on the receiver will be noticeable and that during the demodulation no difficulties are encountered. When the ignition voltage of the glow lamp is selected for instance at 120 volts, the transmitter will become effective only at approximately sin..alpha. = 23.degree. so that the unavoidable capacities can have no disadvantageous effect.
In the U.S. The network frequency is set to 60 Hz. In Europe the network frequency, however, is mostly 50 Hz. In order to come from this 50 Hz-frequency to the 100 Hz-frequency, there can be used a known rectifying bridge that is known to double frequency. Such a rectifying bridge is shown in FIG. 6 at the right bottom location thereof.
If one proceeds from a network frequency of 60 Hz, it is advantageous if the receiver used as a mechanical oscillator as the impulse giving means provides a frequency of 120 Hz. It is possible again to work for this purpose with the same known bridge rectification circuit. The description proceeds collectively from a network frequency of 50 Hz. However, nothing changes with respect to the basic manner of operation when operating with a network frequency of 60 Hz. The German word "Tastluecke" means time spacing between the individual sending impulses. In this "Tastluecke" or literally "feeler gap" or condition the sender amplitude is null. The wording "keying space" also would be the correct in translation for "Tastluecke."
In order to maintain the current use and heat development as small as possible, there are electronic construction elements such as transistor diodes and Zener diodes used in the sender and receiver circuitry as shown in FIGS. 3 and 6.
The return coupling loop with the filter 7 is so constructed as shown by FIG. 7. Transistor 20 is a pnp transistor.
As to the manner of function of the inventive circuitry the following statements can be made. There is to be proceeded therefrom that there lies or exists on the emitter of the transistor 25 on the one hand the generated EMK or electromotive force generated in the coil 21b through the swinging of the tuning fork means 22, 22a and on the other hand the synchronizing impulse coming by way of the transistor 20. The EMK has a sinusoidal-form shape with a positive and a negative half wave or cycle. In the case of synchronous running form impulse and swinging of the tuning fork, the impulse (which is positive) falls together with the parting line of the positive half wave and is superimposed upon the same.
During the positive half wave of the EMK generated in the coil 21b the transistor 25 is blocked which means the same represents a high resistance. During the negative half wave the transistor 25 is more or less strongly conductive so that the condenser is more or less shorted.
If the frequencies of the impulses and the tuning fork means diverge only so little from each other that the impulse still occurs at the time of the positive half wave of the EMK, then the pulse partially reaches the base of the working transistor 24 and switches the same so that the current which flows through the drive coil 21a becomes amplified.
If the frequencies of the impulse and the EMK diverge further strongly from each other that the impulse occurs at a time in which the EMK is passing through the negative half wave, then the impulse blocks the transistor 25 and comes again by way of the condenser 29 to the base of the working transistor 24. This becomes conductive and the drive coil 21a at the time of the impulse has an additional current flowing therethrough. This amplified or strengthened current flow through the coil 21a repeats itself with each arriving impulse so long until the frequency of the tuning fork means corresponds with that of the arriving impulses.
If the network and thereby the arriving impulses completely drop out, so the impulses are generated for the drive of the tuning fork alone through the guidance or control of the working transistor 24. The base of the transistor 24 is preconnected by way of the resistance 28 whereby a small current flows over the emitter distance and the drive coil 21a. The EMK induced in the control coil 21b reaches with the positive half waves thereof while the operation of the transistor 25 is blocked by way of the condenser 29 again to the base of the transistor 24. Thereby, current flows through the drive coil 21a. Also in this case, there is maintained accordingly the swinging of the tuning fork.
The sender 33 in FIG. 6 represents a transistor circuit with a sending coil 34 of conventional or known type. The carrier wave generated from the transistor circuit is modulated with the signal generated by the rectifier 35 in a conventional manner by way of superimposing of both frequencies.
The receiver in FIG. 2 provides a known amplifier 6 and a known demodulator 8. Both are formed by transistor circuits known in themselves. In FIG. 7 there is illustrated the circuit of the receiver 6, the filter 7 and the demodulator 8. In FIG. 7 the corresponding circuit parts are designated with these identifying numerals.
In FIG. 7 there is illustrated an electrical circuit in which the amplifier 6, the filter 7 and the demodulator are suitably arranged. At the input of the amplifier 6 there is arranged a receiver circuit or antenna 5 consisting of a condenser 38 and a coil 39. A first transistor 41 is supplied by way of a signal emitted from a sender or transmitter according to FIG. 6 by way of a condenser 40. The amplifier 6 is formed by a two-step transistor circuit which operates with the transistors 41 and 42. The resistances of this amplifier circuit are designated with the reference numerals 43, 44, 46', 46, 47. The emitters of the transistors lie upon mass or ground. The collectors of the transistors lie above the resistances 44 and 46 on the positive pole of the battery. The condensers 48 and 49 serve for coupling. The condenser 49 couples the collector of the transistor 41 onto the base of the transistor 42; the condenser 48 couples the collector of the transistor 42 onto a transistor 50 of the filter circuit 7. The filter circuit consists of the transistors 50 and 51 and provides resistances 52, 53, 54, 55 and 56. The collector of the transistor 50 lies on the one hand above the resistance 52 on the positive pole of the battery. On the other hand, the base of the transistor 51 lies on the collector. The emitter of the transistor 51 represents the output of the filter circuit 7 leading to the demodulator 8 and the same is connected by way of the emitter-resistance 53 to mass or ground. Simultaneously, there is a double-T-filter engaging on the emitter of the transistor 51 and one filter branch thereof is formed by the resistances 54 and 55 and by the condenser 59 and the other branch thereof is formed by the condensers 57, 58 and the resistance 56. The resistance 56 and the condenser 59 lie or engage with an end thereof on the mass or ground.
The demodulator is connected to the filter circuit 7 by way of a condenser 60. The same provides two transistors 61 and 62. The resistances of the demodulator are designated with the reference numerals 63, 64, 65, 66, 67 and the condensers thereof are designated by the reference numerals 68, 69, 70. On the basis of the transistor 61, there is connected the condenser 60. The base of the transistor 62 is connected with a potentiometer consisting of resistances 63 and 64 and the same is coupled by way of the condenser 68 to the collector of the transistor 61. The collectors of the transistors 61 and 62 lie over the resistances 65, respectively, 66 on the positive pole of the battery. The emitter lies upon the mass or ground. The resistance 66 is connected parallel to the condenser 69. On the collector of the transistor 62 there is connected a return coupling branch which provides a condenser 71 and a resistance 72 and leading by way of the resistance 45 to the base of the transistor 42.
The collector of the transistor 62 lies over the condenser 70 on a potentiometer consisting of the resistance 67 and a resistance 73. A transistor 20 is also connected to this potentiometer. The polarity of the transistor 20 is the reverse of that of the other transistors. The circuit connection of the transistor 20 and the further construction elements was described in detail already previously. The reference numerals pertaining thereto are the same as in FIG. 3.
The means which modulate the carrier wave of the sender are the rectifier bridge circuit and the connection thereof with the sender coil whereby the connection with the sending coil especially occurs by way of the circuit as characterized by the following:
The transmitter includes current controlling means in circuit with rectifier means.
The current controlling means is in series with rectifier means.
The current controlling means is in the form of a glow lamp having an ignition voltage which is about half of the normal network voltage.
The demodulation occurs in a receiver in a conventional manner by way of a known circuit which is illustrated in FIG. 7 mentioned earlier.
FIG. 2 illustrates a schematic diagram or block circuit in which the amplifier 6, the filter 7 and the demodulator 8 are connected sequentially in series. Such circuitry can also be illustrated as though the amplifier 6 were connected directly with the demodulator 8. With reference thereto, however, there must be noted that such direct connection would not be entirely correct and justified. Both right transistors of the receiver 6 actually would already be considered to be attributed to the filter 7 and particularly on the basis of the manner of function of this filter. This is particularly so constructed that return coupling or feed back is provided so that frequencies appearing at the emitter of the right transistor encounter a resistance 15 k .OMEGA. upon the input at the left of both right transistors and particularly in a manner that all those frequencies which are located adjoining the desired frequency are permitted to pass and thus being given as counter coupling upon the input of the left transistor, whereas the desired frequencies are expressed and accordingly no counter-coupled signal is applied to this transistor. In this manner, only those frequencies appear on the left transistor of the demodulator 8 that are desired for the results being sought. The input of the left of both right transistors of the receiver 6 is provided by way of a condenser on the output of the transistor T2 which together with a further transistor preconnected therewith forms the actual receiver amplifier means.
In summary with respect to the foregoing, those statements are better and more understandable that are directed thereto that the receiver 6 consists of the receiver circuit illustrated entirely to the left in the drawing as well as the amplifier including both left transistors. The filter 7 inclusive with both aforementioned transistors are arranged subsequent to this receiver 6 and arranged thereafter finally is the demodulator 8 in the form as illustrated in the drawing. Thus, the illustration of the receiver 6 should provide sufficient disclosure thereof to accomplish the functions as involved herewith.
With respect to a signal in response to deviation of the network frequency by a predetermined amount from the rated frequency thereof, there can be set forth as to the source of said signal an explanation of the corresponding part of the collective manner of operation. There is to be understood that in the circuit there is not necessarily generated a separate signal in order to make the electrical oscillator so-called operative or inoperative. There is much more involved the fine distinction that by way of the transistor 20 there is an impulse, namely the synchronizing impulse as to the oscillator circuit, in other words, transistors 24, 25, control coil 22b and operating coil 21a as well as tuning fork 22 being given whereby the automatic control or self-regulation of the oscillator circuit is dependent thereon as to amplitude thereof in which measure these synchronizing impulses are synchronously in phase with the automatic control or self-regulating impulses of the oscillator circuit. The circuitry operates thereby in the manner that with existing synchronization there suffices the synchronizing impulse already delivered by way of the transistor 20 to supply the necessary current to the driving or operating coil 21a. By way of the simultaneously applied corresponding positive potential at the upper terminal or clamp of the control coil section 21b, there is generated in the emitter-base circuit of the working transistor 24 such a collective potential that this transistor now is only "partially" conducting, in other words, this transistor gives off a weak current by way of the emitter thereof to the drive coil section 21a.
If in contrast there exists no complete synchronization between the synchronizing impulses of the transistor 20 and the automatic control or self-regulating impulses of the oscillator, so during the time while the synchronizing impulses and the automatic control or self-regulating impulses do not coincide, the transistor 24 is controlled or regulated to conduct further and delivers a higher current to the working coil section 21a than would be the case during coincidence of both impulses at a time. In this manner, there is assured that the summation of the current generated by way of the synchronizing impulses are by way of the automatic control or self-regulating impulses in the working coil section 21a as a result always equal regardless of whether phase synchronization exists or not.
It is, of course, to be understood that the present invention is, by no means limited to the specific showing in the drawings, but also comprises any modifications within the scope of the appended claims.
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