Monitoring operation of electrical loads, esp. vehicle lamps - using current dependent sensing resistance driving failure warning device

摘要

A device (100) for monitoring the functioning of electrical loads, esp. vehicle electric lamps, uses an electrical resistor (12) in the load current circuit which has a control switch (10). The resistance voltage drop controls a failure warning device. The device contains few components and can thus be cheaply produced. It is compact and can be produced as an integrated circuit if required. The sensing resistor has an impedance ranging with current. It is pref. a pyroelectric conductor and its voltage can drive the warning device directly. Alternatively, a current limiting resistor may be included.