When hooked up to a car power system, the voltage can fluctuate between
8v and 15v from cranking to running off the alternator.

What kind of valtage regulation is done inside things like Amps, and
Headunits, DVD players (especially the more like mini computer ones)
etc.

Or are they built from components that have a fairly wide input voltage
range that won't burn out from the variances that they are likely to
face under normal use?

TIA
--
Carl Robson
(The poster formerly known as Skodapilot)
http://www.bouncing-czechs.com