Russell McMahon wrote:
> >
> > i need to get a stable 12v supply (at least 1amp, peaks might=20
> > be higher) from a 8..16v source (car battery) to run a harddisk.
> > what's the best / easiest way to do this?
> >
>=20
> EASIEST way is to have a separate battery charged from the=20
> main one via a Schottky diode or a FET rectifier followed by a=20
> low dropout regulator. (A power MOSFET can be switched to=20
> provide almost no voltage drop when conducting.)
>=20
> Suitable filtering for spikes etc will be eased but not eliminated=20
> by the separate battery. Battery will charge at most times when=20
> vehicle is running.
>=20
> Without such an arrangement you need a buck-boost regulator.=20
> MANY designs available but some learning needed in most cases.


Some great net surfer posted two months ago (guess who):
++++++++++++++++++++++++++++++++++++++++++
"[EE:] Miniature PC motherboard madness ... Power supplies"

Ultra tiny automotive power supplies for new ultra tiny ATX motherboards

Also ultra-tiny Compact Flash to IDE interface PCB.

    http://www.via.com.tw/en/VInternet/power.pdf

++++++++++++++++++++++++++++++++++++++++++


P12C508A based automotive power supplies with the schematic and code.

Mike :-)

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