AH> I agree. How about, using a 12V and a 6V battery in series,
AH> giving 18V in total. That would still be enough to step down
AH> to 12V regulated, without wasting quite as much power.
This has some advantages, since it would reduce the dissipation in the
regulator needed to get to 12V, but has the disadvantage of complicating the
charging circuit. Unless you take great care to select the batteries
appropriately, you cannot just put a charging voltage across the two batteries
in series and expect them both to come up to full capacity. If you have two
more or less identical batteries, then this is a lot easier to manage.
AH> I agree with all this. The box I would be putting this on
AH> only consumes 13W, so I can't see any point designing one
AH> that can supply 200W, as long as I know its limitations, and
AH> don't try to power ten full height 5 1/4" MFM hard drives
AH> from it ;)
Assuming about 50% excess capacity for hard drive motor start and some future
expansion, you are almost dead on the 20W design target I suggested.
-- Mike