A circuit arrangement for revealing light signal errors, in particular for railway safety systems, includes an electronic signal generator, which can be disconnected in a reversible manner in the event of an error, and a control part, configured for incandescent lamps, for controlling and monitoring the signal generator. The device for revealing errors includes an error differentiator between the line-related interference voltage and error of the signal generator. The reliability of the error differentiation is improved and rendered independent of capacitive intermediate energy storage devices, in that the signal generator is connected to a resistance arrangement such that the signal generator voltage is greater, in high-resistance signal generators, than an interference voltage.