Abstract: The invention relates to a circuit arrangement for igniting and operating a high-pressure discharge lamp provided with a control circuit which limits the voltage to a value Vb across the output terminals of the circuit arrangement such that:Vla<Vb<Vi.wherein Vla is the nominal lamp voltage and Vi is the threshold voltage across the output terminals at which the ignitor starts.

Abstract: A circuit arrangement which is provided with an up-converter (3) which comprises at least an inductive device (31), a switch (32), and a capacitive device (34) which in the operational state is periodically charged with a charging current in dependence on periodic switching of the switch. The switch is switched to the conducting state periodically during a substantially constant time t.sub.on. The circuit arrangement is provided with detection circuitry (I) for direct detection of the charging current. As a result, a load current which has a sinusoidal shape by good approximation is drawn from a connected AC voltage supply source by the circuit arrangement.

Abstract: A DC-AC converter for igniting and supplying a gas discharge lamp (1). The converter has two input terminals (C, D) to be connected to a DC voltage source. The input terminals are interconnected by means of a series arrangement that includes a load circuit comprising at least the lamp (1) and an induction coil (5), and a first semiconductor switching element (6) including a freewheel diode. The load circuit is bridged by a circuit including a second semiconductor switching element (7) with a freewheel diode. The semiconductor switching elements (6, 7) are provided with control circuits for rendering said switching elements alternately conducting. The control circuit (9) of switching element (7) has a voltage measuring point which is connected via a rectifier element (10) to the control circuit (8) of the first switching element.