Abstract: A circuit for monitoring electrical loads, e.g. lamps especially in motor vehicles, comprises a power supply line (14) for supplying electric current for illuminating a lamp (10, 12), and means (58) for providing a reduced electric current through the lamp when not illuminated. A resistor (24) is in series with the lamp, and a comparator (40) is arranged to compare the potential of a point between the resistor and the lamp with a reference potential when the lamp is not illuminated for generating a warning signal in the event of lamp failure. A further power supply line (48) is also provided, and means (50) for establishing a fixed potential difference between the further and the first power supply lines. The comparator is arranged such that the fixed potential difference provides a constant voltage power supply for the comparator.

Abstract: A circuit for monitoring the voltage across a sensing resistor in series with a load, wherein two reference currents are generated, each dependent both on temperature and on the voltage on a power supply line, which voltage is also temperature-dependent and exhibits a temperature coefficient of such a sense and magnitude that the changes in a reference current due directly to changes in temperatures are substantially offset by the changes in that reference current due to changes in the voltage on its power supply line, which changes are in turn due to the same changes in temperature.