Oh, one thing I forgot to include: > a lot of the incoming power in that 30V AC has to be thrown away, in > producing +5V.
So, if my understanding is correct, the 'switching' H744 really isn't much better than a classic linear supply. It still wastes a very large amount of the input power, and it still has a massively heavy transformer in it. Yes? So I wonder what exactly the advantage was in going to the switching approach? Yes, it keeps the output voltage steadier then a pure linear supply could - but I'll bet there are analog approaches that can do the same. (They'd need something that can produce a steady reference voltage, but the switching approach needs, and has, the same thing.) Maybe the main output transistors are happier being full-on or full-off, or something like that? Noel