Abstract: A circuit arrangement for igniting and operating a discharge lamp is provided withinput terminals for connecting a supply source, and a ground terminal, differential-mode and common-mode filters in which inductance and capacitance are incorporated,output terminals for connecting the discharge lamp, anda switch mode power supply connected to the input terminals and the output terminals by respective voltage conduction branches.The circuit arrangement is characterized in that the input terminals and output terminals are connected both to one another and to the ground terminal by respective capacitive filters, in that a bead is included in one of the voltage conduction branches, and in that further common-mode capacitance is present between the inductance and the switch mode power supply. The requirements formulated in both EN55022 and EN55015 can be complied with in this manner.

Abstract: An electronic ballast for driving a fluorescent lamp includes an electromagnetic interference (EMI) filter and power circuit, a preconditioner coupled to the EMI filter and power circuit and an inverter circuit coupled to the preconditioner for energizing the fluorescent lamp. The preconditioner includes an active power factor controller and a boost circuit which is controlled at least in part by the active power factor controller. The active power factor controller has a reference voltage input to which is applied a reference voltage. At start up, the inverter provides a time varying signal which is rectified.

Abstract: A circuit arrangement for igniting a high pressure discharge lamp includes a secondary winding of a pulse transformer which is at least partially capacitively shunted forming a tuned filter. The tuned filter preferably forms a band pass filter for passing the second harmonic of the signal produced by a pulse generator. An increase in the supply of current during take-over results thereby minimizing the time required for ignition.

Abstract: An integratable transformer circuit for converting an asymmetrical input signal into a pair of symmetrical output signal currents and requiring only one IC connection pin. The circuit exhibits a low input impedance combined with good noise, gain and intermodulation performance up to high frequencies. The asymmetrical input terminal of the circuit is coupled to a node commonly coupled to the emitter of a common base transistor and to the base of a common emitter transistor. The common base transistor acts as a non-inverting current follower, the common emitter transistor as an inverting transimpedance amplifier. An input signal current is transferred to a first symmetrical output terminal via the node and the common base transistor, thereby producing a signal voltage at the node. This signal voltage modulates the collector current of the common emitter transistor, which is in phase opposition to the input signal current and is transferred to the second output terminal.

Abstract: The invention relates to a circuit arrangement for operating a lamp (La), provided withballast means (B) for generating a lamp current from a supply voltage,a memory (M) in which a relation between a number of temperature-dependent lamp parameters has been laid down,means (II, IV, Va, Vb) coupled to the memory for changing lamp operation in dependence on the temperature.According to the invention, the temperature-dependent parameters are the voltage across the lamp, the current through the lamp, and the luminous flux of the lamp. The actual luminous flux of the lamp is determined by means of the memory through a measurement of the voltage across the lamp and the current through the lamp. The luminous flux of the lamp can be controlled to a substantially temperature-independent and substantially constant level in that this actual value of the luminous flux is used as a signal in a control loop, with the exclusive use of electrical parameters.

Abstract: A DC-DC ZVS PWM converter circuit which utilizes the leakage inductance of an output transformer and a three-step operation cycle so as to reduce the voltage stress on the converter power switching transistors and to reduce the EMI noise emissions of the circuit.

Abstract: The device comprises an electrically insulating substrate comprising a principal section (3). First and second principal surfaces (1a, 1b) of the principal section (3) support first and second pairs of conductor tracks, respectively. Each pattern comprises a series of coil elements (7), opposite each coil element of the first pattern there being situated a coil element of the second pattern. Each coil element (7) comprises a spiral-shaped conductor track, having an inner end (9) and an outer end (11), and some coil elements are electrically interconnected in a two-by-two fashion by means of a connection track (13) which extends between their outer ends, the connection tracks on each of the two principal surfaces extending opposite parts of the other principal surface which are free from connection tracks. The principal section (3) is folded, so that the coil elements are situated in mutually parallel planes.

Abstract: A method is described for recording an optical information carrier, in which marks representing recorded data are written at different writing speeds by radiation pulse of equal length and power, independent of the writing speed. The number of pulses per unit length of the written mark is a constant independent of the writing speed.

Abstract: The invention relates to a fan unit for generating gas streams, in particular for vacuum cleaners, which unit comprises an impeller wheel (1) and a motor (4), which is a radial induction motor comprising an external stator (2) and an internal rotor (3), the stator (2) comprising a laminated core (2a) with coils (2b) arranged in slots, the rotor (3) comprising two concentric cylinders (3a, 3b), of which the outer cylinder (3b) is made of an electrically highly conductive material and the inner cylinder (3a) is made of a magnetically highly conductive material, one of the two axial end faces (3c) of at least one of the two rotor cylinders (3a, 3b) being in planar contact with the impeller wheel (1), the motor (4) being energised by means of a frequency changer (29 to 37) and the speed setting being derived from process-dependent nominal values and adjustable set-point values.

Abstract: Recording apparatus for recording in a track on an optical information carrier a first channel signal representing a main information signal, a second channel signal representing a cue information signal and a third channel signal representing a sub information signal. The main information signal includes at least one programme item and the cue information signal includes for the at least one programme item an indication of its location on the track.

Abstract: Step dimming of a fluorescent lamp load through sensing of power line interruptions generated through the toggling of a switch. The number of power line interruptions through toggling produced within a predetermined period of time identifies the level of dimming desired. In the event that interruption of power to the ballast exceeds the predetermined period of time, the lamp load will be reset to a prefixed level of illumination once power is restored.

Abstract: A circuit arrangement for powering a load having n terminals includes n branches. One of the terminals of the load is switchably connected to a first or a second terminal of a voltage source by each of the branches resulting in a voltage vector having n components being applied to the load. The vector components can each assume two values based on the voltage of the voltage source. A control circuit sets the n components of the voltage vector to one of the two values. When all n components assume the same value within some portion of a given period of time (referred to as null vector) and provided that at least one of the components of the voltage vector during this given period of time reamins at this same value, the control circuit sets all components of the voltage vector to the other value so as to form a second null vector.The circuit arrangement prevents a voltage on a terminal of the load from being sustained at a given voltage beyond a given period of time without corrective action being taken.

Abstract: A method of converting a series of m-bit information words to a modulated signal. For each information word from the series an n-bit code word is delivered. The delivered code words are converted to the modulated signal. The code words are distributed over at least one group of a first type and at least one group of a second type. For the delivery of each of the code words belonging to the group of the first type the associated group establishes a coding state of the first type. When each of the code words belonging to the group of the second type is delivered, a coding state of the second type is established which is determined by an information word belonging to the delivered code word. When one of the code words is assigned to the received information word, this code word is selected from a set of code words based on the coding state. The sets of code words belonging to the coding states of the second type are disjunct.

Abstract: The drive system (210) comprises an electronically commutated motor (220) having three windings (225, 226 and 227). The motor (220) is energized by an energizing circuit (270). The energizing means (270) is controlled by three Hall elements (241, 242 and 243) which supply sensor signals (H.sub.1, H.sub.2 and H.sub.3). The motor comprises a permanent-magnetic part whose position is measured by means of the Hall elements. The drive system (210) comprises a status generator (280) which generates status signals (Q.sub.1, Q.sub.2, Q.sub.3 and Q.sub.4) which are dependent upon the ratio between the actual values of the sensor signals (H.sub.1, H.sub.2 and H.sub.3). The drive system (210) further comprises a multiplexer (290) and an inverter (295) which are controlled by the status signals (Q.sub.1, and Q.sub.2, respectively) in order to generate a position signal (P). A corrected position signal (P') is applied to a comparator (260) to generate an error signal (E).

Abstract: The invention relates to a circuit arrangement for operating an incandescent lamp with a current of periodically changing polarity, which circuit arrangement is provided with a static converter (I) with power switching means (T1, T2) and capacitive means (C1, C2) for generating the current of periodically changing polarity. The circuit arrangement also comprises starting means (II) for starting the static converter. According to the invention, the circuit arrangement is provided with delay means (III) which delay the start after connection of a supply source.

Abstract: The invention relates to a drive device for a rotary anode of an X-ray tube having a drive motor with a stator (10) and a rotor (15; 21) which drives the rotary anode, the stator (10) and the rotor (15; 21) being separated by a gap and the stator (10) having slots (11) whose circumferential length (17) has been dimensioned for driving a bipolar X-ray tube. In order to enable a more universal use of such a drive device the stator (10), which has been dimensioned for driving the bipolar X-ray tube, is also used for driving a unipolar X-ray tube, the diameter of the rotor (21) and thus the gap (22) being dimensioned in such a manner that the efficiency or the torque of the drive device lies within a maximum range (II).

Abstract: In a voltage converter for converting an AC input voltage into a DC high voltage and further DC power supply voltages, in which the AC voltage applied to the converter is applied to a rectifier arrangement (1, 2, 3, 4) whose output signal is coupled to two consecutively switched electronic switches (6, 7), and in which this DC voltage is converted into the DC high voltage and into the DC power supply voltages, the circuit arrangement has a simple structure in that a series arrangement of a capacitance (8), an inductance (9) and a primary winding (10) of a transformer (11) is arranged in parallel with one of the electronic switches (6, 7), in that a secondary winding (12) of the transformer (11) precedes a capacitance (15) at the output end, in that a control circuit (20) is provided which controls the switching frequency of the electronic switches (6, 7) in such a way that a DC voltage of the desired value decreases across the capacitance (15) at the output end, and in that the transformer (11) is provided wi

Abstract: An inductor has a winding arranged on a straight magnetic core formed by a plurality of ferrite cylinders disposed in line with one another with a space between adjacent cylinders. The ferrite cylinders are accommodated in a common cylinder made of a molded plastic material which has a helical groove in its outer cylindrical surface. The inductor is used for the injection of a low-frequency current into a cable of a CATV system.

Abstract: The invention relates to an axial-flow induction motor comprising a stator having a winding arranged in a slot and a rotably supported laminated rotor which is spaced from the stator by an air gap. The rotor has a magnetically highly conductive layer on the side which is remote from the stator and an electrically highly conductive layer on the side which faces the stator. In order to reduce losses caused by harmonics, the rotor also includes an additional magnetic conductive layer between the electrically highly conductive layer and the air gap. The magnetic conductivity of the additional magnetic conductive layer in the direction of rotation is low in comparison with the magnetic conductivity of the magnetically highly conductive layer. The electrically highly conductive layer is also thicker than the magnetically conductive layer.

Abstract: A circuit arrangement for operating a discharge lamp with a high frequency current comprising input terminals for connection to a source of low frequency supply voltage, a rectifier bridge coupled to the input terminals for rectifying the low frequency supply voltage, and an inverter shunting a first capacitor for generating the high frequency current. The circuit arrangement incorporates two power feedback loops to feed power back to an output terminal of the rectifier bridge. As a result the circuit arrangement has a relatively simple configuration, causes only a very limited amount of harmonic distortion and can be realized with relatively cheap and simple components.