I need to covert 12vdc from lead storage battery to 5.0 vdc for use as a USB source. I have 7850s lying around. Will they work, and if so, will some kind soul please tell me how to do it. I'm not a total moron, just no EE.

Thanks Much
Jm

Old post, just saw it, I think you mean a 7805, 78 meaning a positive regulator, the 79 is a negative voltage regulator. 05 is the voltage.
:http://www.electro-tech-online.com/attachments/electronic-projects-design-ideas-reviews/4953d1118218789-need-help-about-7805-regulator-circuit-boosted_lm7805.png