Abstract: In a circuit for an inductively stabilized discharge tube (1) provided with two preheatable electrodes (2, 3) the ends of one electrode (2) are connected via a first capacitor (22) and a second capacitor (24), respectively, to the corresponding ends of the other electrode (3). The second capacitor (24) remote from the supply is shunted by a PTC resistor (23). The discharge tube (1) and inter alia the PTC resistor (23) form part of a lamp unit. The discharge tube (1) ignites readily even at low ambient temperatures. In the lamp operating condition, the influence of the PTC resistor (23) is neglible.

Abstract: The invention relates to a high-pressure sodium vapor discharge lamp which comprises a discharge tube provided with an external starting electrode. In accordance with the invention the lamp comprises a transformer wherein the secondary winding of the transformer is connected between the starting electrode and a main electrode of the discharge tube, the primary winding of that transformer being included in an oscillatory circuit including a glow starter. These further components of the starting circuit form part of the lamp. In this construction proper starting of the lamp is achieved with minimal insulation near the input terminals of the lamp.

Abstract: A device for starting a discharge lamp by means of a transistor starter provided with an auxiliary transistor for stopping the starting procedure if the lamp fails to ignite.A zener diode is included in the control circuit of the auxiliary transistor, a capacitor is connected in parallel across the lamp, and a self-inductor is included in the connection from the lamp to the main transistor. The auxiliary transistor has a second function in that, by the action of the zener diode, the auxiliary transistor delays the conduction of the main transistor so that a large rise of the voltage between the lamp electrodes is produced, which provides a more reliable ignition of the lamp within a large temperature range.