[sdiy] RC, LC we all c RFin HiZ

[Roy J. Tellason]

On Tuesday 13 July 2004 12:44 am, mark s wrote:
> let's start with an ideal (wish):
>
> is there an effective way to eliminate, at the input of the circuit, all
> frequencies above, say 50kHz, leaving the audio band untouched ? placed at
> the input of a circuit, it would prevent all the bad stuff from getting in
> through the input cable, at least.
>
> ok now go ahead and school me :^)  but please share your techniques for
> reducing AM, FM and the rest of it.
>
> i'll ante: a 10nF or even better 20nF cap across the input jack has worked
> wonders for me. but sometimes you need more....

I'll do that,  and also put a ferrite bead on the wire.  It's worked wonders 
in those stereotypical situations where you get police radio coming through 
on church sound systems...	:-)

Good groundhing helps,  too.