[sdiy] DC wallwart +/- on-board V Reg ?

[Joe Frey]

I concur. The noise from mine is subdued, not removed.

On Mar 6, 2015 5:02 AM, Andre Majorel <aym-htnys at teaser.fr> wrote:
>
> On 2015-03-05 17:07 +0000, Tom Wiltshire wrote: 
> > On 5 Mar 2015, at 16:35, Justin Owen <juzowen at gmail.com> wrote: 
> > 
> > > I was hoping to get some advice on the potential 
> > > advantages/disadvantages/benefits/costs of circuits that use 
> > > a DC wall wart adapter (e.g. 9V boss-style adapters) to 
> > > power a voltage regulator (e.g. LM317) which then powers the 
> > > circuit - versus designs where the circuit is powered 
> > > directly from the wall wart (e.g. guitar pedals)? 
> > 
> > Noise is the biggest issue in my view. 
> > 
> > With a 9V-from-external-wallwart, you have no idea what the 
> > power looks like. If you've got a regulator in between, you 
> > can be reasonably sure you're getting clean voltage of the 
> > right level. 
>
> About 10 years ago, I read something to the effect that getting 
> rid of the noise of a switch-mode power supply by following it 
> with a linear voltage regulator does not work. Not as well as 
> people think it should, anyway. 
>
> Sorry for making unsubstantiated claims but I cannot find the 
> source now. I think it may have been some app note mentioned 
> here. Anyone remember which ? 
>
> -- 
> André Majorel http://www.teaser.fr/~amajorel/ 
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