f2 by holding the output frequency of the converter 20 and of the oscillator 10 to a predetermined low value this value lies near the resonance frequency f0 with which the still undamped the lamp has not yet ignited resonance circuit supplies high ignition voltage after successful ignition the effect of the monostable flip flop 11 on the oscillator 10 is removed so that the steady operation i e the modulation and pulsation of the current can be utilized the ignition achieved in this way corresponds to a cold start if desired hot start can be provided by utilizing the ignition capacitor c1 as shown in fig1 if the pulsed mode operation of gas discharge lamps allows a change in their characteristics and an improvement in their light output this is achieved according to the exemplary embodiments of fig3 and appropriate control of the device shown in fig1 and 2 by retaining a single choke and by an alternating astable exchange between two frequencies this frequency modulation leads to a change in the effective reactance f l1 which gives rise to a current main pulse with low frequency and a holding current pulse with high frequency f2 the respective amplitudes and intervals t1 t2 of the pulses are tuned so that averaged over time t the lamp is supplied with the power p n the direct change of the lamp current by frequency modulation.