Abstract: The invention relates to an electronic ballast for operating a discharge lamp LA, in which a pump circuit D6, C8, C9, L1 charges an intermediate circuit capacitor C6 from the AC voltage of a converter V1, V2. A voltage limitation circuit R8, R3, D5, R4, R5, C3, SD is connected in parallel with the intermediate circuit capacitor C6. A dissipation element R8 in the voltage limitation circuit R8, R3, D5, R4, R5, C3, SD converts electrical energy into thermal energy when a maximum value for the voltage across the intermediate circuit capacitor C6 is exceeded. The current through the measuring resistor R3 is measured as the voltage UC3 across the measuring resistor R3, is detected in a delay circuit R4, R5, C3 and is used to control a shutdown device SD for the converter V1, V2.

Abstract: In the case of an apparatus for providing a sinusoidally amplitude-modulated operating voltage, two switches are arranged in the form of a half bridge, and an LC element is arranged downstream of the half bridge. The first switch is driven by a first square-wave signal in a clocking with the amplitude modulation frequency per clock cycle, and the second switch (QLOW) is driven by a second square-wave signal, which is shorter than the first signal, with a temporal offset with respect to the first signal in each clock cycle. The LC element (LMOD, CMOD) acts as a filter for the signal resulting from the driving of the switches at a connection point (K) between the switches and allows a DC voltage component and a sinusoidal component of the signal with the fundamental frequency of the clocking to pass through, but substantially filters out harmonics.

Abstract: The present invention relates to a circuit arrangement for driving a gate of a transistor, in particular a MOSFET, which is arranged in an electronic ballast, the circuit arrangement (2) being designed for the variable driving of the gate (221) as a function of the operating state of the electronic ballast. The invention also relates to a method for driving a gate of such a transistor.

Abstract: The elongate bulb (1) of a lamp, which defines a longitudinal axis (A), is closed at mutually opposite ends by sealing parts (6; 32), in which foils are inserted. The foils are axially folded, the cross section of the foil having the shape of a W with three bends, at least the central bend having a radius of curvature of from 0 to 0.6 mm.

Abstract: The invention relates to a method for varying the power consumption of capacitive loads, in particular compact fluorescent lamps which are operated using a phase-gating dimmer by means of a converter (step-up converter). According to the invention, in the case of a nonconducting dimmer (i.e. no system power supply to the load), the switch (T1) in the converter (step-up converter) is closed. In the case of a conducting dimmer (i.e. when a system voltage is applied to the load), the step-up converter operation takes place until a predetermined maximum voltage is reached across the smoothing capacitor of the load.

Abstract: The invention relates to a novel operating circuit for a low-pressure gas discharge lamp 1 in the case of which a digital controller 12 is designed such that by gradually lowering the operating frequency in the ignition procedure it initiates shutdown operations of a safety shutdown device for excessive currents through a lamp inductor 10 in order thereafter to increase the operating frequency somewhat. It is possible overall in this way to achieve an ignition, for example by repeated pulsed ignition operations as far as shutdown operations, or else by a continuous ignition operation at a minimum frequency at which no shutdown operation occurs. The invention has the advantage of being insensitive to temperature fluctuations and component tolerances and, moreover, of permitting the lamp inductor 10 to have comparatively small dimensions.

Abstract: In order to improve the starting of a dielectric barrier discharge lamp it is proposed to provide means for igniting an auxiliary discharge inside the exhaust tube (5) of the lamp.