Pic Dude wrote:

> > > I need to build a power-supply to run a PC in a car,

> > You'll need a Low DropOut regulator.
>
> Among other things, since a low dropout still needs overhead
> voltage above 12V.  Figure 1V (just a guess since I haven't
> yet investigated this).  So I need 13V min at all times in the
> car.  If the current requirement for the 12V portion is low
> enough (to be determined), I could regulate 12V to 8V, run that
> thru a doubler to get 15-16 volts, and regulate that to 12V.


How about this idea; build a simple SMPS that
generates 3v and has an isolated output, and put it
in SERIES with the 12v car supply. Done right, it would
BE the regulator and self-adjust to maintain 12v to
the PC. So input voltage can be 8v to 15v, and the
output is always regulated 12v. The total SMPS power
only needs to be 1/4 the power of the total supply,
unlike all other solutions which require the SMPS
to supply 100% of the power. :o)
-Roman

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