On Wednesday, in article
<eQVaNE2C8$ id>
Don' "Jim Crowther"
wrote:
> In demon.tech.pc, on Tue, 7 Jul 2009 19:28:29, andrew fox wrote:
>
> >i was thinking of the magnetism being a bad thing to electrical
> >thingumies
> >
> >any way of checking on magnetic levels?
>
> I suspect it depends on whether you believe copper bracelets relieve
> rheumatism.
I recall there being something about the permanent magnet in a speaker
being able to damage a CRT monitor by distorting the aperture grill in
the tube. And, of course, you have speakers in TVs, and add-on speakers
for home cinema, and they're safe.
A permanent magnet doesn't cause any electrical interference, that would
only come from the current through the speaker coil, creating a varying
field, which would induce a current in a nearby circuit. Same physics as
a transformer, but...
1: A speaker's coil is pretty well blocked from affecting the outside
world by the permanent magnet.
2: Getting a significant current would need a coil very close to the
speaker's coil, not just a pcb track in the router box.
3: Very low-level analogue signals, usually called "noise", are just
what digital circuits ignore.
Conclusion: no risks.
--
David G. Bell -- SF Fan, Filker, and Punslinger.
On the horizon, a carrier task force of the Salvation Navy was
turning into the wind, preparing to launch Zeppelins.
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