Abstract: A circuit arrangement suitable for operating a high-pressure discharge lamp (80) in conjunction with a controlled current limiter (6) by means of a control signal which is at least composed of the sum of a lamp-voltage-dependent signal part and a lamp-current-dependent signal part. The invention, the absolute value of the lamp-current-dependent signal part is chosen to be smaller than the absolute value of the lamp-voltage-dependent signal part. The circuit arrangement provides a rapid control, which keeps the lamp voltage substantially constant.

Abstract: A circuit arrangement for operating at a supply voltage V.sub.n a high-pressure sodium discharge lamp (4) having a lamp voltage V.sub.la in conjunction with a current limiter circuit (3) and a first controlled semiconductor switching element (1). The circuit arrangement comprisesa first part of comparing a proportional part of the lamp voltage V.sub.la with a reference voltage V.sub.r anda second part for comparing a proportional part of the supply voltage V.sub.n with the resultant of the first comparison. The circuit arrangement makes it possible to operate the lamp so that the lamp voltage V.sub.la is substantially constant.

Abstract: An energization arrangement for a discharge lamp includes a DC/AC converter to which a discharge lamp (81) is connected. The lamp is shunted by a relay contact (90) to obtain an electric circuit through which two electrodes (83, 84) of the lamp can be preheated. It is advantageous to insure that the relay contact is closed before a voltage occurs between the electrodes of the lamp. This prevents the lamp from exhibiting a transient flash at too cold electrodes. A timing circuit (40-47) ensures that the relay contact remains closed for about 1 second, after which the lamp ignites with warm electrodes. No electrical losses occur in the relay winding (30) during operation of the lamp.

Abstract: The invention relates to a d.c. to a.c. converter comprising two transistors (22, 25) and an output transformer (21). This converter also includes an auxiliary d.c. voltage source (43) and is provided with an auxiliary winding (40) of the transformer (21) which connects the base of one transistor (22) to the base of the other transistor (25).According to the invention, the combination of the auxiliary d.c. voltage source (43) and a control circuit of the two transistors (22, 25) comprises a current blocking means (44) such that the converter can be supplied with a pulsed d.c. voltage. Consequently, that converter can be operated from a low frequency a.c. voltage mains via an auxiliary full-wave rectifier (5 to 8), which does not need to have a high value smoothing capacitor.