[sdiy] filter for noisy DC power supply

[rsdio at audiobanshee.com]

It's possible that your gizmo has poorly-designed ground. The battery doesn't cause a problem because it is completely floating. The wall-wart is possibly creating a ground loop. This is worst when power supply ground currents run through the same traces as audio ground currents. There's no way to filter that out - it requires changing the traces.

Does your gizmo have balanced inputs and outputs? If they're unbalanced, how do you handle ground without injecting power supply noise onto the ground line? These can be tough challenges for audio design, but you can probably find some articles online. Is this a gizmo that you designed?

Brian


On Oct 22, 2014, at 2:50 AM, David Griffith <dgriffi at cs.csubak.edu> wrote:
> My gizmo is powered by an ordinary wall-wart power supply.  This supply is giving a hum to the output.  There is no hum when powered by a battery. Would someone please point me in the right direction of some simple filter circuits to clean up the hum?
>