Abstract: The application relates to a ballast for the pulsed-mode operation of gas discharge lamps (EVG) and a use of a self-excited or externally controlled half or full bridge circuit for the same purpose. An EVG of the mentioned kind has a buffered feed d.c. voltage (U.sub.dc, udc) from which the utilized power for the GE lamp or GE lamps can be derived. The load circuit in which the GE lamps are provided has a series-connected choke (L1), if necessary a capacitor (C1) can be connected in parallel to the lamp for ignition purposes. Such a circuit is to be so configured that it is possible to change the characteristic light values, i.e. the light output and the color temperature of the gas discharge lamps (GE). This is to be realized without mechanical choke switching and is achieved in that at least one electronic switching element (S1) or at least one such switching element pair (S1, S2, S3, S4) are provided which supply the choke (L1) and the GE lamp periodically with voltage pulses (u.sub.ac).