Ahhhhhh thanks fellas. You blokes are fantastic.
I would agree it seems silly to go 12v DC--->240v AC then back to
19v DC within the laptop PS. Probably very inefficient.
I was really sorta only worried about the shape of the square wave
in the 'modified sine wave' types and how well lappy supplies go..
As there hasn't been a wave of 'bloody thing blew up my laptop' stories,
initially I thought they must be fine.
But , yes, I suppose it all comes back to efficiency. You would want the most life in a battery from a remote site. So less steps the better.
Looks like DC to DC it is...thanks guys....off to Jaycar I go
ps: Trevor...I'd love to get the pure sinewave job but , yeah they sure are
pricey.
I'd be curious to see just what that waveforem looks like on my CRO.