Circuit arrangement for protecting a filament lamp against failure, in particular for motor vehicles and traffic light systems

摘要

A circuit arrangement is specified for protecting a vehicle lamp against failure, having two incandescent filaments (2, 3), arranged in a common lamp bulb, in which the first incandescent filament is connected via a coil (10) in whose magnetic field a magnetically controllable resistor (9) is located which is part of a resistor bridge. The bridge voltage preferably controls the circuit of the second incandescent filament of the two-filament bulb via an operational amplifier (5) and a transistor (4) connected downstream. As soon as the first incandescent filament is interrupted, as a result the second incandescent filament is switched on via the transistor (4) as a replacement due to the change in the bridge voltage. A relay can also be used instead of a semiconductor switch. <IMAGE>