Abstract: A circuit arrangement for igniting and operating at least two discharge lamps. the circuit is provided with input terminals (K1,K2) for connection to a supply voltage source and a circuit I (SC, S1, S2) coupled to the input terminals for generating a high-frequency voltage from a supply voltage delivered by the supply voltage source. A load branch B is coupled to the circuit I and comprising a first branch A including first terminals (K3,K3') for accommodating a discharge lamp and a first inductive element L1, and a second branch C shunting the first branch A and comprising further terminals (K4,K4') for accommodating a discharge lamp and a second inductive element L2 which is magnetically coupled to the first inductive element L1. A circuit II limits the voltage across branch A and branch C to a first value during the ignition of the discharge lamps.

Abstract: The invention relates to a switching device for operating a lamp by means of a high-frequency current, which switching device comprises a DC-AC converter whose oscillation frequency is determined by a timer circuit comprising a resistor and a capacitor. In accordance with the invention, the timer circuit also comprises a chain C which includes a switching element and which is used to increase the RC period of the timer circuit during ignition of the lamp, thereby increasing the amplitude of the voltage across the lamp.

Abstract: A circuit arrangement for igniting and operating a discharge lamp (1) comprising inductive means, which include a primary winding (PRIM) which passes a high-frequency current during ignition and during lamp operation, and a secondary winding (SEC) which is magnetically coupled to the primary winding and electrically coupled to an impedance M (C1, C3) for limiting the current passed by the secondary winding. The current through the secondary winding generates a DC voltage via rectifying means, by which current a part of the circuit arrangement is supplied. The circuit arrangement is also provided with apparatus X (R, S1) for increasing the impedance value of the impedance M after ignition of the discharge lamp. The amplitude of the DC voltage is thereby at a desired level both before and after ignition of the discharge lamp, while no major power dissipation takes place during stationary lamp operation.