[sdiy] Shielding

[Theo]

You may have a point there.
Theo

From: Tom May <tom at tommay.net>

> "Theo" <t.hogers at home.nl> writes:
>
> > Moho Disco said the noise was not there when the laptop ran of
batteries.
> > Think that rules out the sound card
> > and points a heavy finger to wards a ground loop.
>
> I'm clearly not an expert, but I can't buy that.  The laptop supply
> most likely has a two-prong plug and the output is isolated through
> the transformer.  At least, that's how my laptop works.  So where's
> the loop?  Or maybe the powercord is an antenna?  Does it make a
> difference whether it's plugged into the wall or not?
>
> Recently I noticed our baby monitor receiver had the same problem:
> little or no hum when running off a battery, major hum when running
> off a wallwart.  When I used better quality wallwarts on both
> transmitter and receiver, the hum was reduced substantially.  Perhaps
> the laptop has the same problem :-)
>
> Tom.