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

[JH.]

Amen, too.

I'm mostly using LM317, but not because of the noise.
You can improve the noise a lot on a 317 with an extra
capacitor and diode, see data sheet,  - but I rarely do this.
What I like about the 317 is that you can trim it to the exact
voltage easily.

Always design your Audio circuits as if you had a very noisy
power supply. Noise from the regulator, or spikes from
other modules, you don't want them to go into your audio.
Always filter manual CVs that are derived from the supply
voltage with potentiometers.

JH.


> Amen.  What he said !!!
>
> H^) harry
>
> Paul Perry wrote:
> >
> > 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
>