The referenced U.S. Pat. No. 4,647,817, Fahnrich et al, describes the circuit to which the present invention relates. This circuit has a heater circuit loop which includes a series circuit of two capacitors and a positive temperature coefficient (PTC) resistor in parallel to one of them. The heater circuit provides for good pre-heating of the electrodes and, therefore, rapid and flicker-free firing or ignition of the lamp, that is, discharge through the discharge space of the lamp. The circuit works well. The PTC resistor, however, remains in the circuit throughout the entire operating period of the lamp and, hence, some energy is used thereby, which is not converted into the desired light output. Continuous heating of the PTC resistor additionally thermally loads the circuit arrangement.