Schaltungsanordnung zum Betrieb elektrischer Lampen

摘要

The invention relates to a circuit arrangement for operating electric lamps, in particular fluorescent lamps. The circuit according to the invention preferably comprises a free-running half-bridge invertor 2, 3 which is provided with a disconnecting device which disconnects the invertor in the case of a faulty lamp L by cutting off the control signal from a transistor 3 of the half-bridge. The disconnecting device contains as essential elements a field effect transistor 23 which is connected in parallel with the control electrode of the transistor 3, a bistable multivibrator 17, 18 which drives the gate of the field effect transistor 23, and a threshold-value switch 26 which resets the bistable multivibrator 17, 18 in the case of a faulty lamp L, leading to the field effect transistor 23 switching on and thus the invertor being disconnected.