Electronic ballast for fluorescent lamps

摘要

Since the DC voltage of the DC voltage source (9) builds up only slowly after switching on, in the case of the electronic ballast, the push-pull switch arrangement (12, 13) is not activated until the DC voltage has reached a specific minimum value. As the DC voltage builds up, it charges an energy store (24) whose charging time constant is much shorter than the time constant of the build up in the DC voltage (Ug). When a threshold value is reached at the output (29) of the energy store (24), the switching element (30) (diac) switches on and switches the transistor (12) into the conductive state. The fluorescent lamp (19) is initially pre-heated by the oscillations of the operating tuned circuit (LC) and is then reliably started. Flickering during starting of the fluorescent lamp is prevented. <IMAGE>