SV: Re: [sdiy] Linear PSU options .. 7815/7915 vs LM317/LM337 vs 723 etc

[Paul Perry]

There's another side to this regulator debate, and that is:
just how good does the regulated supply need to be?
When one looks at precision analog circuitry, you often see
power rails no better than you would get from a LM78xx,
but wherever a *really* precise voltage source is required, there is a 
precision source dedicated to just that. And it is right there on the 
board where it is wanted.
Which at a stroke solves the problem of noise generated on the 
power rails by switching transients etc.
And, speaking of transients...... anyone serious (including some
members here, I notice) have separate power rails for the digital stuff,
and for the analog that they try to keep noise free.
I personally think, the difference between the 78xx and other regs,
is swamped by these other techniques..... and if you want to go the 
whole distance, you are going to need to have precision voltage
diodes & separate analog/digital lines anyway!

paul perry Melbourne Australia