> The 12v laptop power is also more efficient. Fewer power conversion steps.
No, that's not true. All these PSUs are switch-mode; their efficiency is dictated by the design and the selection of components. Even linear regulators are no longer that fussed about the overall drop across them - as most of them are actually hybrid, with a switch-mode supply doing the bulk of the conversion, and a linear reg on the end to get the low ripple/noise rejection etc. There are very few volts dropped across the linear part, so little power wastage. Vic. -- Please post to: Hampshire@mailman.lug.org.uk Web Interface: https://mailman.lug.org.uk/mailman/listinfo/hampshire LUG URL: http://www.hantslug.org.uk --------------------------------------------------------------