Abstract: An arrangement for synchronizing the PWM clock signals of several clocked direct voltage converters uses commercially available control circuits for controlling the converters. In the case where the TDA 4714 and TDA 4716 units are used as the control circuits no connection for synchronizing the switching clock signals is provided. The arrangement guarantees the synchronism of the oscillators of all the control circuits and features apparatus by which the phase shift between two switching clocks of two arbitrary direct voltage converters can be chosen to amount to 0.degree. or 180.degree..

Abstract: A semiconductor device having the advantages of bipolar transistor characteristics (such as a low ON resistance) and of FET characteristics (such as a rapid turn-off) can be obtained by integrating and merging together in one semiconductor body a bipolar transistor T and two or more insulated-gate FETs T1 to T4. A lateral FET T1 is formed by providing a drain region adjacent to the base region of the bipolar T and an insulated gate overlying an intermediate channel area. A further FET T3 which is of complementary conductivity type to T1 may have a source region provided in the drain region and an insulated gate over a channel area between the source region and the emitter region of T. These insulated gates are connected together, for example as a common gate grid, so permitting T1 to be turned on to extract charge from the base region of the bipolar T during turn off when T3 is turned off to interrupt the terminal connection to the emitter region of bipolar T.

Abstract: A power supplier for providing a regulated high-frequency AC output with a bucking and boosting section and a push-pull output section in which a common switching element is used in both the bucking and boosting section and in the push-pull output section.

Abstract: An adaptation circuit (3) for operating a high-pressure discharge lamp (1) via a controlled semiconductor switch (4) in series with the lamp. The control circuit for the switch (4) to comprise a voltage division circuit (5,6). The voltage division circuit is connected in parallel with the switch when the lamp is connected to the circuit output terminals (E,F) and one branch of the voltage division circuit comprises a parallel-combination of a capacitor (57) and a resistor (56). Thus, the variation of the voltage across the lamp influences the control of the semiconductor switch so that it is possible to stabilize, for the major part, the power dissipated by the lamp against, variation in the supply voltage and against lamp voltage variations during the life of the lamp.

Abstract: A device for pressing a stack (5) of sheets against a roller drive (2,4) of a papersheet separator, said device compromising a pivotable pressure plate (11) which is biased against the roller drive (2,4) by means of an adjustable leaf spring (12) in order to vary the pressure force. In this way a pressure force is obtained which suits paper sheets of different kinds. The device may be applied for example in printers and copiers.

Abstract: A hearing aid, in particular a behind-the-ear hearing aid, comprising a first unit (1) that includes an amplifier (4), a hook (3) formed with a duct (16) and a space (8). A second unit (2) includes an electro-acoustic transducer (12). The second unit is intended to be worn in the ear. A tubular element (15) for the mechanical connection of the two units accommodates connecting means (14) for electrically coupling the transducer (12) to the amplifier (4). The element (15) is axially slidable inside the duct. This enables the hearing aid to be adapted to the size of the ear of the person wearing the hearing aid. The connecting means (14) is long enough so that even for a big ear, the electrical connection is still intact or can be made. When the hearing aid is adapted to a smaller ear, the connecting means (14) is then too long but the space (8) takes up the excess length of the connecting means.

Abstract: The invention relates to an optoelectronic device for surface mounting of the type comprising an insulating substrate, whose upper surface receives at least one optoelectronic element electrically connected to contacts of the lower surface of the substrate through conductive strips. An annular spacer is fixed to the upper surface of the substrate. A spherical lens is glued on the annular spacer and the plane of light emission is situated at a distance from the spherical lens which is smaller than its extension.

Abstract: A surface acoustic wave device in which the two ports of an input transducer (2) provided on a piezoelectric substrate (1) are coupled to the two ports of an output transducer (3) via respective reflective multi-strip couplers (12, 13). In order to avoid the necessity of providing external tuned matching components to attain the low potential insertion loss of such a device, the number of electrodes and center-to-center distances of the electrodes of at least one of the transducers are chosen so that the impedance of that transducer is substantially real for a range of frequencies which contains the center-frequency of the device response characteristic as determined by the couplers.

Abstract: A field effect transistor for high-frequency applications includes, on a monocrystalline semi-insulating substrate, a thin active n-doped layer of a material having a high electron mobility, on whose surface are deposited two ohmic contacts forming the source and drawing contact regions of the transistor, between which a metallic contact constitutes a gate electrode of the Schottky type. According to the invention, the transistor is characterized in that a dielectric layer is deposited on the active layer between the source and gate electrodes on the one hand and between the gate and drain electrodes on the other hand, and in that the metallic layer constituting the ohmic contacts is continuously prolonged on this dielectric layer without causing a short-circuit with the gate.

Abstract: A method of manufacturing a semiconductor device having an integrated circuit in an epitaxial layer on a substrate in which the epitaxial layer comprises islands of conductivity type opposite to that of the substrate which are surrounded laterally by a surrounding region of the same conductivity type as the substrate, is disclosed. Both the islands and the surrounding region are formed by diffusion from buried layers through the epitaxial layer. A bipolar transistor is provided in at least one island. The p-n junctions between the islands and the surrounding region are substantially at right angles to the surface. The invention involves a method of manufacturing the device and is of particular importance for realizing very compact and fast circuits with low dissipation consisting of a combination of CMOS bipolar subcircuits.

Abstract: A circuit for operating a discharge lamp (1) by means of a direct voltage. The circuit comprises direct voltage terminals (A,B) for connection of a direct voltage source, alternating voltage output terminals (K,L) for connection to the discharge lamp, a direct voltage/alternating voltage sine converter (3), and a current limiter (5) for limiting the current through the lamp in its operating condition. A controllable direct voltage converter (2) is coupled between the sine converter and the direct voltage input terminals.

Abstract: The invention relates to a modulator comprising a first differential amplifier (6) which receives an input signal and a correction signal for adjusting the quiescent currents on the first and second output. The first differential amplifier (6) is coupled to a second differential amplifier (19) and a third differential amplifier (22), which receive the carrier signal and which supply the modulated signal. A difference signal proportional to the difference between the current of the first output and the current of the second output of the first differential amplifier (40) is applied to a low-pass filter (25), whose output signal is applied to a control amplifier (40). The control amplifier (40) supplies the correction signal to the second input of the first differential amplifier (6) via a storage device (50).

Abstract: A transconductance amplifier comprising a voltage divider including two identical resistors (R.sub.o) connected between the bases (3, 4) of two first transistors (T.sub.o1, T.sub.o2) arranged as a differential pair, each having a first emitter area (e.sub.o). The junction point of said resistors (R.sub.o) is connected to the base of a second transistor (T.sub.1) having a second emitter area (2e.sub.1), whose emitter, like that of the first transistors (T.sub.o1, T.sub.o2), is connected to a current source (6). For a ratio between the second and the first emitter areas (2e.sub.1 ; e.sub.o) equal to 4:1 the difference between the output currents (I.sub.1, I.sub.3) of the first transistors (T.sub.o1, T.sub.o2) increases as a linear function of the input voltage over a range which is as large as possible.

Abstract: The invention relates to a (static) memory which is divided into a number of memory blocks, memory cells being arranged in rows and columns in each memory block. A row in a memory block is activated via a selection gate whereto there are applied an inverted row selection signal (which is applied to all memory blocks) and a non-inverted and an inverted block selection signal (which is applied to all section gates in a memory block). The selection gate comprises a P-MOS transistor and two parallel-connected N-MOS transistors. The junction between the P-MOS and the N-MOS transistors constitutes the gate output (for activating a row of cells). The row selection signal is applied to the gate electrode of the PMOS transistor and of a first N-MOS transistor. The inverted block selection signal is applied to the gate electrode of the other N-MOS transistor and the block selection signal is applied to the main electrode of the P-MOS transistor.

Abstract: A gear mechanism (1) is selectively reversible between two end positions and which comprises a driving gear member (3), which can alternately be driven in opposite driving directions (19, 20) and a driving member (5) which can be driven by said driving gear member, one gear member (3) being partly toothed to form a toothed portion (8) which is bounded by two end faces (6, 7). The gear members can be brought into and out of mesh with each other. For bringing the two gear members (3, 5) into mesh with each other in at least one driving direction (19, 20) of the relevant gear member (3) said members carry a pair of actuating stops (34, 35, 43, 44) which correspond to the relevant driving direction, which are axially offset relative to the teeth (8, 9), and which each comprise a stop surface (36, 37, 45, 46) whose geometry is in conformity with that of a tooth-flank surface (38, 39, 47, 48).

Abstract: An electro-dynamic transducer of the isophase or ribbon type includes a vibratile diaphragm (7) arranged in the air gap of the transducer magnet system and having a current conductor (9) arranged thereon. An additional layer (23, 24) of material is arranged on at least one part of the diaphragm, e.g. in a space (11) between the pole plates. In order to extend the operating frequency range of the transducer, the additional layer is divided into sections (25, 26) with the area of each section being at least an order of mangitude smaller than the area of the one part of the diaphragm. These sections are distributed more or less uniformly over the one part of the diaphragm. It is possible to reduce distortion and increase the sensitivity of the transducer.

Abstract: A circuit arrangement for producing a direct voltage from a sinusoidal input voltage comprising a filter for suppressing interference voltages, a rectifier, a switched mode power supply part and a pulse generator. The pulse generator produces from the rectified input signal switching pulses for the switched mode power supply part. The frequency of these pulses is varied so that it is a minimum at the maximum value of the rectified input voltage and is a maximum at the minimum value and is varied between the extreme values so that the second derivative of the frequency with respect to time is always zero or negative. A switching pulse is terminated when a signal proportional to the output current of the rectifier exceeds the difference between a signal proportional to the rectified input voltage and an integrated signal proportional to the output current of the rectifier.

Abstract: A measuring oscillator for measuring temperature has an all-pass filter (1) which drives a current source (16) having a controllable amplification factor and a control element (17). The control element is connected to the control input of the current source (16) and controls its amplification factor in a manner such that the amplitude of the alternating voltage produced by the measuring oscillator assumes a constant value. The all-pass filter comprises a phase-determining bipolar circuit arrangement (10) comprising a voltage follower (12), whose input is connected to one terminal (9) of the circuit arrangement (10) and whose output is connected through an ohmic input resistor (13) to the inverting input of a first operational amplifier (14), which is fed back negatively through a measuring resistor (15) having a temperature-dependent ohmic resistance value. The output of the first op-amp also is connected through an ohmic resistor (41) to the one terminal (9) of the bipolar circuit arrangement.

Abstract: The efficiency of a semiconductor cathode can be increased by bombarding the electron-emitting regions (8) with an electron beam (8), which frees the surface from adhered oxygen particles. The electron beam preferably originates from a second semiconductor cathode (42), which has an opening (42) for passing the electron beam (20) of the first semiconductor cathode (20). Alternatively, both semiconductor cathodes can be realized in one semiconductor body.