positive voltage regulator that can work maximum with 24 volt I have aUsing a linear regulator for 50V in and 5V out is a bad idea, since you will get a loss of 88.9% min.
http://www.datasheetcatalog.com/datasheets_pdf/L/7/8/0/L7805C-V.shtml (http://www.datasheetcatalog.com/datasheets_pdf/L/7/8/0/L7805C-V.shtml)
Where I can buy a positive voltage regulator that can work with 50 volt
also I search after a driver that can control a motor that work with 110 volt and 50 ampereI'm afraid that you'll have to device one yourself to keep it from being really expensive.
the system work with 50 [hz]