A method and a circuit arrangement are described for operating a discharge lamp is described, especially a high-intensity discharge lamp or lamps (HID) or UHP [ultra high performance]-lamp, which is/are distinguished by a first and a second operating phase with a higher first or a lower second frequency of the lamp AC, wherein the operating phases are activated alternatingly at defined intervals and for defined periods of time, in order to achieve a stable arc discharge and only a low burnout or rise in burning voltage of the lamp during its life by configuring certain forms of electrode tips. Furthermore, are described an illumination unit with a discharge lamp and such a circuit arrangement as well as a projection system with a projection display and such an illumination unit.