Abstract: A DC/DC converter of the flyback/forward converter type includes a switch (S), a transformer (T), a first diode (D1), a first capacitor (C1), a second diode (D2) and a second capacitor (C2). The first and the second capacitor are arranged in series between the output terminals (K3, K4) of the DC/DC converter. The DC/DC converter has a high efficiency and is very suitable for operating a lamp with a DC current.

Abstract: A ballast preconditioner serving as a boost regulator which includes a power factor controller. The preconditioner also includes a capacitor for producing a substantially DC voltage and a switch for controlling the amount of energy stored in the capacitor in response to a switching signal. The power factor controller includes a waveform generator having a look-up table for storing values of at least one waveform. The switching signal produced by the power factor controller is based on the at least one waveform accessed from the look-up table.

Abstract: A circuit arrangement for operating two or more discharge lamps in parallel, includes a transformer in a resonant load circuit. Each of the lamps is part of a series arrangement of the lamp and a capacitor. The operating frequency is chosen below the frequency for which the phase shift between the voltage and current in the load circuit is minimal. During operation, the amplitude of the current in the load circuit is relatively low so that power dissipation in the load circuit is also very low.

Abstract: A load-dependent, preventive fuse with an electronic ceramic (12) in a housing (11) from which connection leads (14) are led outwards to detect at least a first type of load to which a device to be monitored is subjected, in which fuse use is made of a ceramic material, hereinafter referred to as TDR ceramic (12), whose electrically insulating state changes as a function of time, being the first type of load, and as a function of a second type of load, to a semiconducting state, and as a result thereof, when a dc voltage U is applied to the TDR ceramic (12) via connection leads (14) an increase in current forms the activation criterion for the fuse, which criterion is fulfilled under predeterminable conditions and determines a desired operating time .tau..

Abstract: In a self-oscillating bridge circuit, the control of the low switch (6) is derived from the control of the high switch (7) by coupling the control circuitry (SC2) of the low switch to a terminal P in the control circuitry of the high switch by means of a diode (D1). The control of the low switch is improved by incorporating control circuitry (SC3) for rendering the low switch conducting for a short period after the high switch has become non-conducting.

Abstract: A method and a device in which information is written on a medium and is read out, and which establishes whether the information read is sufficiently reliable, and in which so-called erasure information is used to establish the influence of media defects and other imperfections on the occurrence of errors in a transmission system. The medium is, for example, a hard disk containing one or more bad spots whose location can be accurately detected. The implementation of the method makes accurate and fast computation of the bit error rate possible.

Abstract: An identification transponder comprising an identification code generator (10) embodied as an integrated circuit predominantly comprising organic materials. The integrated circuit may be provided on an anti-theft sticker (5) accommodating an LC resonant circuit (3, 4).

Abstract: Commercially available transition mode ("TM") power factor correction ("PFC") pre-regulator integrated circuits ("IC") typically have an output pin that is used to control a MOSFET in the power output circuit as well as a multiplier input pin that is used to set the peak current that is conducted by the MOSFET on a cycle-by-cycle basis. A portion of the rectified line voltage typically is applied to the multiplier input pin. Zero crossing distortion in the input line current is significantly decreased by reducing the range of the portion of rectified line voltage applied to the multiplier input of the TM PFC IC. The range may be reduced in any convenient manner. For example, one technique adds a clamping device such as a Zener diode to the voltage divider used to sense the rectified line voltage, so that the peak value at the PFC IC multiplier input is clamped if the rectified line voltage exceeds a certain value.

Abstract: A circuit arrangement comprising a DC-AC converter for operating a lamp (La). A first capacitor is connected across first and second inputs of the DC-AC converter. A first coil and a second capacitor are connected in a series circuit to first and second outputs of a rectifier circuit coupled to an AC supply voltage. Two diodes are serially connected between the first output and the first input. A third capacitor is connected between a junction point of the two diodes and a junction point between two series connected transistors of the DC-AC converter. The diodes, the coil (L1) and the second and third capacitors (C2, C3) are so dimensioned that the resonance frequency of a series circuit of the coil and the second and third capacitors connected in parallel is approximately equal to the operating frequency of the DC-Ac converter. As a result, the circuit arrangement has a high power factor.

Abstract: A circuit arrangement for powering an electric motor having at least three windings from a direct voltage source via a commutation circuit which, for each winding terminal of the electric motor, comprises a commutation branch including a first and a second switching element by which the relevant winding terminals can be connected selectively to a first terminal of the direct voltage source or, via a measurement impedance, to a second terminal of the direct voltage source. A ring counter device periodically changes over the switching elements of the commutation circuit in accordance with a signal series which is cycled through the ring counter device under control of a clock signal, one period of the ring counter device corresponding to one complete cycle of the signal series through the ring counter device. A clock frequency generating stage supplies the clock signal whose clock frequency is dependent on the measurement voltage.

Abstract: A circuit for operation of a semiconductor light source having terminals for connecting a source of power and output terminals for connecting the semiconductor light source. The circuit is also provided with a controlled current generator and is also concerned with a signal head incorporating the circuit. The controlled current generator is controlled by the current flow through the semiconductor light source and the current supplied by the controlled current generator.

Abstract: A circuit for operating a discharge lamp having circut input terminals for connection to a supply voltage source and an inverter coupled to the circuit input terminals for generating an AC voltage at a frequency f from a supply voltage supplied by the supply voltage source. A piezotransformer has transformer input terminals coupled to the inverter output terminals. Terminals for lamp connection are coupled to the inverter output terminals and is provided for detecting whether the lamp has ignited. A protective device is coupled between the output terminals of the inverter and the transformer output terminals so that the inverter is effectively protected against damage due to ignition pulses generated by the piezotransformer.

Abstract: A circuit arrangement for feeding a single-phase or multi-phase load from a sinusoidal alternating voltage energy supply mains which carries an at least having a frequency for which the load has a substantially resistive behavior. The circuit arrangement includes a full-wave rectifier stage for deriving a substantially sinusoidal intermediate circuit voltage, a modulation stage, for example, a single-phase or multi-phase inverter, which generates from the intermediate circuit voltage, under the control of a control signal whose frequency is high relative to the frequency of the mains alternating voltage, at least one high-frequency supply voltage which is applied to the load. The supply voltage (voltages) is determined from the product of the control signal and the intermediate circuit voltage. A high-frequency filter stage is coupled to the full-wave rectifier stage so as to suppress interference induced into the energy supply mains in a frequency range which includes the frequency of the control signal.

Abstract: An electronic ballast having an RF resonant inverter and RF feedback from the inverter which provides power factor correction. The feedback is provided by a capacitor coupled between an RF resonant tank circuit of the resonant inverter and a low frequency point in the ballast. Such feedback integrates the power factor correction stage with the RF resonant inverter stage and eliminates a switch and its controller. Electronic ballasts operating at RF frequencies require fast switching isolation diodes. Ultra-fast silicon diodes with very short recovery times, which have been used as such isolation diodes, are sensitive to ambient temperature and deteriorate the power factor and total line current harmonic distortion of the ballast. Use of either GaAs or silicon carbide isolation diodes instead of silicon diodes provides the ballast with a high power factor and a low total harmonic distortion.

Abstract: A circuit arrangement for operating a lamp has circuit input terminals for connection to a supply voltage source. An inverter is coupled to the circuit input terminals for generating an AC voltage with a frequency f from a supply voltage supplied by the supply voltage source and includes inverter output terminals. A piezotransformer has input terminals coupled to the inverter output terminals. Terminals for lamp connection are coupled to the inverter output terminals. A detector detects whether the lamp has ignited. The transformer input terminals are connected to the inverter output terminals only by means of passive components and the inverter comprises means coupled to the detector for changing the frequency f in response to the ignition of the lamp. The circuit arrangement is simple and inexpensive and need not provide a device for switching the piezotransformer out of the circuit after ignition of the lamp.

Abstract: A ballast feedback scheme including a single stage current feedback inverter. To avoid overboosting of the voltage impressed across a buffer capacitor only a portion of the high frequency lamp current is fedback to the buffer capacitor during both ignition and steady state operation of the lamp. Ignition of the lamp is well controlled.

Abstract: A transformer, particularly for a voltage converter, has a primary winding having a predeterminable leakage inductance and at least one secondary winding magnetically coupled to the primary winding with a predetermined voltage-transformation ratio. The (primary) leakage inductance is increased as compared with a conventional transformer without violating the limits for implementing an appropriately functioning transformer, and without choosing an additional coil or a larger core than is required for the power transformation, in that the primary winding comprises at least two winding sections whose magnetic couplings to the at least one secondary winding are implemented such that they operate in mutually opposite senses and are arranged such that they are at least substantially magnetically decoupled from one another.

Abstract: A circuit arrangement for operating a lamp comprising input terminals for connection to a supply voltage source. A DC-AC converter is coupled to said input terminals for generating a high frequency signal. A piezoelectric transformer having a primary side that is coupled to the DC-AC converter and a secondary side that is coupled to terminals for lamp connection and a dimming circuit for adjusting the light output of the lamp. The DC-AC converter generates a substantially square wave shaped signal and the dimming circuit is coupled to the DC-AC converter for adjusting the lamp light output by adjusting the duty cycle of the substantially square wave shaped signal. A lamp operated by the circuit arrangement is dimmable over a wide range while the amount of power dissipated in the circuit arrangement is relatively low, even when the lamp is dimmed.

Abstract: A circuit arrangement for supplying a discharge lamp, comprising a converter for generating a high-frequency current with a frequency f from a supply voltage. The converter comprises at least one switching element which is rendered alternately conducting and non-conducting at the frequency f while the discharge lamp is being supplied. In addition a circuit portion I is provided for the low-frequency modulation of the power consumed by the discharge lamp through an adjustment of the conduction period of the switching element. As a result, instabilities in the discharge lamp plasma, such as striations and moding, are suppressed to a considerable degree.

Abstract: A circuit for supplying a discharge lamp, comprising a converter for generating a high-frequency current at a frequency f from a supply voltage and a circuit portion I for adjusting the power consumed by the discharge lamp through adjustment of the frequency. The circuit portion I is provided with a circuit portion II for low-frequency square-wave modulation of the frequency f and for the adjustment of the duty cycle of the square-wave modulation. As a result, the discharge lamp can be dimmed over a very wide range without striations or moding occurring and without undesirable shifts in the color point of the light.