I have a device that requires an AC adaptor rated at 120V AC input, with 21.5V, 300mA DC output. Seems this is a bit unconventional as I can't find anything like this anywhere, and I'm wondering if there's a way to make one. I was thinking that I might somehow combine a couple 12V adaptors, it doesn't have to be pretty at all. I'm good with a soldering iron, but bad with the physics. Can anyone help me?