Diagrama Esquemático:
http://www.mediafire.com/view/lknjj95prt684qj/Power_Supply_Voltage_Switch_01.JPG
http://www.mediafire.com/view/w6ca2whdzie81fs/Power_Supply_Voltage_Switch_02.JPG
http://www.mediafire.com/view/cjy1p9b22vp8vhs/Power_Supply_Voltage_Switch_03.JPG