I have an old Asus Eee that I'm using for digital modes. Its power brick generates 9.5V @ 2.5A -- where can I find schematics that will help me design a power supply that can use my shack's 13.8VDC to drive this thing? Bonus points if RFI is kept to a minimum.
Go to any of the major semi manufacturer's websites (e.g. www.national.com www.ti.com
etc.), select power management, select either linear or switching, you'll get a little screen where you put in Vin, Vout, and current, and then get a menu of parts.
Or... go to any online marketer and buy a car charger for your Eee, put a cigarette lighter jack on your 13.8V shack supply, and you're golden.
With most laptops the constraining factor isn't the electronics in the converter itself, it's the weird-ass coaxial DC power connectors.