>
i need to get a stable 12v supply (at least 1amp, peaks might be higher)
from a 8..16v source (car battery) to run a harddisk.
what's the best / easiest way to do this?
>

EASIEST way is to have a separate battery charged from the main one via a
Schottky diode or a FET rectifier followed by a low dropout regulator. (A
power MOSFET can be switched to provide almost no voltage drop when
conducting.)

Suitable filtering for spikes etc will be eased but not eliminated by the
separate battery. Battery will charge at most times when vehicle is running.

Without such an arrangement you need a buck-boost regulator. MANY designs
available but some learning needed in most cases.


        Russell McMahon

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