0
It will be 7805 in which 7 is company code; 8 means positive voltage & 05 is amount of positive voltage output.
http://en.wikipedia.org/wiki/Alternating_currenthttp://upload.wikimedia.org/math/d/7/f/d7f393582339f50cba0a11328ee51e6b.png
.7
7
.7 volts