>> You might take a look at Roman Black's regulator, if I remember correctl= y, it is >> very close to what you need. Roman's circuit is too hard to get reasopnable regulation with in serious u= se. When utter simplicty is needed it may be OK. 'My' GSR with 3 transistors would do the job BUT I did not mention it as the MC34063 has more bells and whistles, costs very little and is readily available. > I was thinking of Olins regulator using a 10F2xx device ... Yes.Olin's PIC based regulators would be OK if topology suits. I liked his high side drive circuit. R --=20 http://www.piclist.com PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist .