Patent ID: 7456578

Claim:
A circuit arrangement having a drive circuit ( 12 ) for a lamp ( 10 ) having a first connection ( 11 ) for a first filament (W 1 ) of the lamp ( 10 ) and a second connection ( 13 ) for a second filament (W 2 ) of the lamp ( 10 ); a protective circuit ( 16 ), which is coupled on the output side to the drive circuit ( 12 ) and on the input side to the first connection for the first filament (W 1 ) of the lamp and the second connection for the second filament (W 2 ) of the lamp such that a first signal, which is correlated with an operational parameter of the first filament (W 1 ), and a second signal, which is correlated with an operational parameter of the second filament (W 2 ), can be transmitted to the protective circuit ( 16 ), characterized in that the circuit arrangement also comprises a modification apparatus ( 22 ) which is connected between the protective circuit ( 16 ) and the first connection ( 18 ) and the second connection ( 20 ), the modification apparatus ( 22 ) being designed to split the first signal and the second signal into a DC component and a AC component for the purpose of providing a modified first signal and a modified second signal.