A power conversion method and apparatus convert an AC input voltage signal or a DC input voltage signal to a DC output voltage signal suitable for driving a DC load. The power converter includes a first voltage stage coupled to a first pair of input terminals to receive a rectified AC input voltage signal....http://www.google.co.uk/patents/US5414610?utm_source=gb-gplus-sharePatent US5414610 - Universal power converter with single, shared power transformation circuit
