Abstract: A transducer for measuring a current, includes a magnetic core which has a gap substantially impeding passage of any magnetic flux, a coil arranged to pass a premagnetizing current for producing a first magnetic field, a loop for carrying the current to be measured, so as to produce a second magnetic field, and a magnetic field comparision device exposed to the magnetic fields. The magnetic field comparison device includes a magnetic film bridging the flux gap. The film is alternately controllable in respective opposite directions of saturation substantially by the first magnetic field, and evaluates the measuring current in dependence of the magnetic fields. The magnetic core, the coil, the loop, and the magnetic film are substantially disposed concentrically.

Abstract: In a measuring apparatus for determining the effective value of the power demand of an energy consumer over a period of calculation, a pulse generator 4 associated with a consumption meter 3 produces fixed quantity pulses. A measuring and calculating means 6 forms measurement values which are proportional to the reciprocal of the time intervals between the fixed quantity pulses and which are summed in a summing means 7. An evaluation means 9, which is in communication with the summing means 7 by way of a communication channel 8, forms the effective value P.sub.eff from the sum of the measurement values. The measuring and calculating means 6 may comprise a microprocessor.

Abstract: In a method of measuring power delivered at an alternating voltage by an alternating current to a load, the steps include comparing the instantaneous alternating voltage and the instantaneous alternating current with a periodically varying reference signal having a relatively high frequency compared to the frequency of the alternating voltage and the alternating current, thereby obtaining a plurality of first voltage-intersection and current-intersection points during the negative-going portions of the reference signal, and a plurality of second voltage-intersection and current-intersection points during the positive-going portions of the reference signal,transforming the measured analog voltage-values and measured the analog current-values into digital voltage-values and digital current-values, respectively, multiplying the digital voltage-values and the digital current values at the first intersection points with one another, so as to obtain a plurality of first instantaneous power outputs, multiplying the

Abstract: In a self-starting unidirectional synchronous motor which includes a stator, an exciting coil at least partly disposed within the stator, a permanent magnet type rotor which has a plurality of rotor poles and is at least partly disposed within the coil, and wherein a space is defined between the rotor and the coil, and the stator includes groups of unshaded main poles and groups of shaded auxiliary poles alternating with each other, and respective end zones are defined between adjacent groups, and each pole generates a corresponding magnetic field, the poles comprise pole arms extending into the space and include half poles disposed at least near the end zones, respectively, and wherein the groups of shaded poles are displaced with respect to the groups of non-shaded poles by respective spatial electrical angles, and the magnetic fields of groups of shaded poles are shifted with respect to groups of non-shaded poles by respective phase angles.

Abstract: A pulse-width modulator circuit includes a pulse-width modulator which has an input for a low-frequency modulation signal and an input for a carrier signal, a carrier signal generator which has an output connected to the carrier signal input of the pulse-width modulator for providing a carrier frequency, a buffer stage postcoupled to the pulse-width modulator, an output filter postcoupled to the pulse-width modulator, including a relatively narrow-band resonant circuit for damping the carrier frequency, and a regulating device forming a feedback path between the resonant circuit and the carrier signal generator for maintaining the carrier frequency substantially at the resonance frequency of the resonant circuit.

Abstract: A variable pulse width generator generates a periodically recurring and variable mark-to-space ratio waveform, so that the ratio of the difference between the space and mark durations to the sum of the space and mark durations is proportional to a selectable voltage, and substantially independent of any resistor values used in the circuit.

Abstract: An apparatus for ultrasonically determining fluid flow passing through a measurement section includes a tube which has two ends and an average predetermined inner cross-sectional area; the tube constitutes the measurement section. A sound-emitting transducer is disposed near one end of the tube, which has a first sound-transfer surface, and a sound-receiving transducer disposed near the other end of the tube, which has a second sound transfer surface. Each sound transfer surface is disposed at a sufficiently large predetermined distance from a corresponding end of the tube, so as to permit the fluid flowing through the tube. A fluid-receiving chamber communicates with the one end of the tube, and has a first average cross-sectional area, and a fluid-discharge chamber communicates with the other end of the tube, and has a second average cross-sectional area.

Abstract: A transmitting device for generating communication signals to be superimposed on an AC distribution network. A resonant load circuit coupled to the network conductors includes a capacitor with a transistor switch and reverse polarity diode connected in parallel therewith. Current and voltage threshold circuits control the transistor switch such that an audio frequency communication signal is generated by the load circuit.

Abstract: A measuring transformer comprises a measuring conductor carrying the current I.sub.m to be measured, a pre-magnetizing winding which carries a pre-magnetizing current I.sub.v, and a magnetic field comparing means which is exposed to the magnetic field produced by the current I.sub.m and the magnetic field produced by the pre-magnetizing current I.sub.v and is alternately controlled in both directions of saturation. The magnetic field comparing means is a magnetic film which may be anisotropic, operated in the magnetic preferential direction, and have a thickness of at most a few microns. It may be secured to pole shoes of a magnetic core or arranged between a flat measuring conductor and a pre-magnetizing coil of flat cross-section. The measuring transformer can be used as an input transformer in a static electricity meter. In a further embodiment, the output pulses can be obtained directly from the magnetic field comparing means.

Abstract: This invention relates to communication systems of the type particularly useful in power line communications. Signals to be transmitted, which can be in the form of short, fixed frequency signals, are expanded in time and/or bandwidth to provide a longer signal with a variable frequency. At the receiver, power line noise, which is typically either short wideband noise or long narrowband noise, is removed and the remaining expanded signal is detected. The expanded signal can then be compressed in time and/or bandwidth to reproduce the original signal.

Abstract: A detector for determining the presence of an electrical signal in the presence of noise, the electrical signal having at least two predetermined characteristics, includes a signal transforming device for obtaining a plurality of independent estimates of each characteristic, a classification device connected to the signal transforming device for sorting the plurality of independent estimates into at least two classes, and a counting device for signaling the presence of the electrical signal, when the number of the estimates within one class exceeds a predetermined number.

Abstract: A projection screen is disclosed having a surface formed by a plurality of irregularly distributed microstructural elements shaped like the outer surface of contiguous bubbles. Also disclosed is a method for making such projection screens.

Abstract: An apparatus for measuring a.c. power which subtracts an average value of current and voltage from sampled instantaneous current and voltage values, respectively. The resultant current and voltage values are multiplied, so as to obtain a power measurement substantially free of any sampling errors and any d.c. levels.

Abstract: The invention relates to a combination of an apparatus for the transfer of fungible goods or services, for example, cashless payment for merchandise or services, with a transfer device having marked thereon a plurality of cancellable value units in the form of at least first and second types of optical markings different from one another, and arranged in a predetermined cyclical sequence on at least one track of the transfer device, without the occurrence of any gaps, but with a transition region formed between adjacent markings. The apparatus includes a reading device, inclusive of a light source, and at least first and second light sensors associated with the first and second types of optical markings, respectively. The reading device is arranged for reading and generating signals from the markings, and from the transition regions, and an activatable erasing device erases the markings in dependence of the number of value units to be cancelled.

Abstract: In a method and apparatus of identifying a document with the aid of at least two different types of optically readable markings disposed on the document, and of at least two light sensors, each individual marking modifying light impinging thereon in a characteristic manner, and wherein each light sensor is associated with a respective marking, and senses the light modified by the associated marking, the steps include placing the markings in a predetermined cyclical sequence on at least one track of the document, so as to avoid the creation of any optically readable gap, thereafter erasing at least selected portions of the markings, while maintaining in selected groups of two adjacent markings at least a portion of one of the markings in dependence of coded information to be recorded on the document, obtaining a timing signal from the light sensors in dependence of the light modified by the markings, with the aid of the timing signal, serially reading out the coded information from the marking portions remaini

Abstract: An optical reading apparatus is described for reading documents which contain information in the form of optical markings which deflect a reading beam coming from a light source in at least one given direction of deflection. A first light sensor detects a deflected partial beam. A second light sensor, the optical axis of which lies in a given direction of deflection, is only receptive to those light rays deflected at the document which lie outside a first cone and inside a second cone which is coaxial with the second light sensor. A comparator compares the electrical signals of both light sensors. Altered markings, which cause additional dispersion of the reading beam, can be reliably distinguished from the unaltered markings.

Abstract: There is described a process for embossing onto a document machine-readable information in the form of optical markings with a light-modifying relief structure for indicating the genuineness of the document, comprising transferring a thermoplastic layer to the document from an embossing foil by means of a hot embossing die, and simultaneously embossing the optical markings in at least the thermoplastic layer. Also described are embossed documents produced by the disclosed process.

Abstract: A process for the protection of electrical systems upon return of power after power interruptions, through the immediate disconnection of secondary consuming units by an audio-frequency control receiver, and the subsequent reconnection thereof in timed sequence. The audio-frequency control receivers have, in addition to a normal control path, a second path, through which, upon return of the voltage, the switch relay for secondary consuming units is disconnected upon reaching 2/3 of the system voltage. The process may be implemented through the use of a two-state D.C. relay, which is controlled by a secondary path including a cold lead to the system voltage. The process may alternatively be implemented through the use of a two-state A.C. relay which is controlled through a half-wave secondary path including a capacitor/resistor parallel circuit.

Abstract: A circuit arrangement for a keyboard is disclosed, in which the switches of the keyboard are each connected in series with a respective LED to form a switch matrix, the rows of which are connected to a multiplexer and the colums of which are connected to an evaluation device. The LED's serve as decoupling diodes, and furthermore form a diode matrix of an optical indication field by which the commands entered into the keyboard through activation of its switches, or other information, can be made optically visible. Upon activation of a transistor switch, a resistor is switched parallel to a measurement resistor, whereby an LED is lighted at the point of intersection of the activated matrix row and matrix column.

Abstract: There is disclosed a method for embossing a relief pattern of high resolution into a thermoplastic information carrier by means of a heatable embossing matrix. The matrix, which exhibits the desired relief pattern, is pressed onto the thermoplastic information carrier, and is then heated by means of an electric current. After the electric current has ceased, the embossing pressure is maintained until the thermoplastic information carrier has hardened through cooling. Alternative methods permits selected variation of the relief pattern to be embossed by selectively altering the surface of the support member which supports the information carrier during the embossing operation or by selectively heating the embossing matrix.