What I want to do is build a 12V lead acid battery maintainer to keep the charge topped off while I intermittently draw up to 5A from the battery. For about $71, I can buy a battery tender that will meet for my needs. http://www.google.com/products/cata...a=X&ei=u4WLTfe3NMiitgeGu5WDDg&ved=0CCgQ8wIwAw# However, I already have a suitable transformer, 5A diodes, regulators (7812 and 317), a good assortment of caps and resistors, and a couple of 2N3055 transistors with heat sinks. Can someone supply a circuit for me? Thanks.