An electric power unit selectable and usable a plurality of electric sources, including an electric source-discriminating device to detect attached electric sources of the plurality of electric sources, an electric source-selecting device to select one of the attached electric sources as a using electric...http://www.google.com.au/patents/US7414332?utm_source=gb-gplus-sharePatent US7414332 - Electric power unit and electronics device obtaining power from a plurality of power sources
