[gmat]

Originally posted by bigben2k
5% is very standard in most circuits.

Exact.

MOSFET do get an input, but it's not exactly a positive half-sine. I seem to remember (from theory) that some of those big caps are there to partly fill those voltage drops (to 0V) at 120 Hz. (60 Hx * 2)

The MOSFET is actually there to remove the 120 Hz "ripple" in an otherwise DC signal, and to level the output to selected voltages.

What's going out of the primary loop (switching) is nearly a half-sine. You're right, a first filter prevents it to drop to zero - for power purposes only, the regulators wouldnt hold otherwise.
If you look at what's given to mosfets in a PC psu you'll going to get a thrill They give a really sh*tty input to regulators. Giving a better signal at input costs a lot.
The mosfets still output good DC but the result is they'll heat up a lot.
Virtually you can give any voltage to a regulator it will always output it's rated voltage, with heat building up with differences * power drain.

The RC i mentioned was after the mosfets, to smooth out even more the output (mainly removing 100 or 120hz remains) and to prevent power spikes due to wires inductance.

-snip-
The R+C is actually a filter. (Correct me if I'm wrong here gmat, 'cause it's still early!). The combination can be calculated to filter out a specific frequency range. It is very commonly used in speakers, in the form of a cross-over, to separate the low frequency signals from the high-frequency signals, in order for the woffer/tweeter to get its rightful part of a sound.

Extacly. The RLC combo (Resistance Inductance Capacitance) is a filter. With it you can build a complex impedance to do anything you want (filtering, oscillating, etc...). Inductance is produced by coils.

I'll have to read up on switched supplies, because I haven't dealt with them in 10 years... [/b]

You have one in your own PC just crack it open and plug in your oscilloscope you're out for a thrill.
I tried that. Now i even wonder how PCs can work with such crappy PSUs.