A number of driving circuits for low-pressure discharge lamps with pre-heating electrodes are known. European Patent Publication No. 0 111 296, September 1987, discloses a brightness control circuit for a low-pressure discharge lamp with two heating electrodes which are each connected to a secondary winding of a heating transformer 4. For brightness control, the lamp is connected via a ballast inductor 2 to a control device 3. Additionally, for stabilization of the possibly variable voltage of the control device 3, the lamp is connected to an auxiliary voltage source, which generates a high-voltage alternating current for maintaining basic ionization. Thus, a circuit arrangement composed of multiple complex modules is involved, which is relatively difficult and costly to manufacture.