No, I'm not giving up. But I'm still looking for an approachable Power Supply schematic, the one posted by homebrew is too overwhelming for me. I'm looking for something like the MAKE Powe Supply but safer.
The Elenco XP-720K is a very simple variable supply offered in kit form. The instructions contain a schematic. It has three supply rails. Two of them are positive and negative variable, using LM317 and LM337 regulators, and the third is fixed 5V, 3A, using LM7805 plus an additional pass transistor. The design is nothing special, and the positive variable rail (the one using the LM317) is almost straight out of the LM317 data sheet.
The mechanical construction of this kit is good, with the regulators mounted on a big heat sink that is directly exposed to outside ventilating air. The case is sturdy metal, and grounded. The mains input is fused. Unlike the MAKE supply, there are no obvious safety flaws that I can see.
This supply suffers the problem of only going down to 1.25V, like many LM317-based designs. Another obvious shortcoming is that it does not have adjustable constant current limiting -- a feature which is extremely useful.
I've built one, and while it's not an innovative design, it is a fairly well-implemented and sturdy version of the standard LM317 type variable supply. If you're thinking of building a 317-based variable supply of your own, this might be a source of ideas. If you search around the web, you can see where different people have used this as a base and added modifications, including meters, 10-turn pots, and other enhancements. The case has a fair amount of room inside for custom additions.
The assembly instructions and schematic are here:
http://www.elenco.com/admin_data/pdffiles/XP720Kweb.pdf