Abstract: A circuit arrangement has a drive circuit for a lamp having a first connection for a first filament of the lamp and a second connection for a second filament of the lamp, a protective circuit, coupled on the output side to the drive circuit and on the input side to the first connection for the first filament and the second connection for the second filament such that a first signal correlated with an operational parameter of the first filament, and a second signal, correlated with an operational parameter of the second filament, can be transmitted to the protective circuit. The arrangement also includes a modification apparatus connected between the protective circuit and the first connection and/or the second connection, the apparatus designed to modify the first signal and/or the second signal and to make them available to the protective circuit as a modified first signal and/or a modified second signal.