A circuit for driving and monitoring a light signal, in particular an LED signal, has an actuating part for outputting a process voltage, and a signal transmitter for setting current windows for daytime operation and nighttime operation. In order to achieve a high degree of independence between the circuit and variable parameters, in particular the power consumption of the lighting elements, the signal transmitter has a regulator which is connected to the monitoring logic via brightness sensors for measurement of the brightness of the light signal, with the monitoring logic producing a daytime or nighttime nominal value of the current window for the regulator.