Electric power supply device for e.g. motor vehicle, has switching equipment connecting through supply voltage at circuit, when voltage detector detects application of another supply voltage at circuit

摘要

The device has a switching equipment (3) connecting through a supply voltage (+V) at an electrical circuit (9), when a voltage detector (7) detects an application of a supply voltage (-V) at the electrical circuit, where the switching equipment is a transistor. A charge pump (4) and a voltage stabilizer (6) are provided for producing the supply voltage (-V) from the supply voltage (+V).