Signal status detecting arrangement has switching units for lamps, voltage detectors, summing units and inverter

摘要

The signal status detecting arrangement has switching units (2 to 4) for the lamps (5 to 7), the voltage detectors (8,9), summing units (10,11,14) and an inverter. The voltage provided by the switching units is detected by the voltage detectors. The reference voltage (20) is always greater than the values determined by the voltage detectors at the switching units.