The generator has an operating mode detector (3) connected with a signal box (1) over an electromagnetic tolerance-protection device (2) at an input side. The detector is connected with a signal generator/driver assembly (4) and a comparator (6) at an output side for feeding current to a LED-light source (7) of a characteristics adjuster (5). The comparator compares a reference-operating mode and an actual operating mode e.g. day and night operations. A measurement value detector (8) is integrated with an evaluator (9) and the signal generator/driver assembly in a control circuit.
