[sdiy] newbie bead question

[Happy Harry]

Ferrite bead.  Its a small 'lossy' inductor that will prevent
very high frequencies from entering or leaving the board ...

these would actually ride on the outer skin of the conductors
and are otherwise hard to trap or filter.

In many cases they are just a 'good idea'... but sometimes they
are very necessary. I had a problem with radio frequencies riding
into a (commercial) mixer via the ground sheild. Even SHORTING the
input to ground did not help (as the signal was on the OUTSIDE of
the ground sheild.

Ferrite beads (a big one in this case) sponged up that unwanted
RF energy....

H^) harry


>From: Bob Roesler <bobo at decapod.net>
>To: sdiy <synth-diy at dropmix.xs4all.nl>
>Subject: [sdiy] newbie bead question
>Date: Mon, 20 May 2002 09:23:34 -0700
>
>Hi all,
>
>In a couple if mixer circuits I've looked at from Ken Stone and Tony 
>Allgood
>there is a bead used in series where +/- power enters.
>
>What exactly is a bead, and why is it used? I've looked in the index of The
>Art of Electronics, and find no reference to such a thing. Nor in any other
>publications I have laying about.
>
>Can someone enlighten me here?
>
>Thanks,
>Bob
>
>




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