Re: [LAU] Terrible mic ground noise

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To: <linux-audio-user@...>
Date: Tuesday, April 2, 2013 - 12:32 am

On Monday 01 April 2013 19:37:44 jonetsu@teksavvy.com did opine:

> Le 01-04-2013 09:58, Gene Heskett a أ©critآ :

That depends to a surprising extent on the surroundings. If everything is
hot, then so are you by capacitative coupling from the environment, so a
shock is not real likely because the currant would have no place to go.
OTOH, if standing on a metal railing that is grounded, and bare foot too,
then touching anything electric without first probing it with one of these
sniffers could be the last thing you touch.

I have found also that even if the metal surfaces are well painted, you can
often detect a hot item by touching it very gently with the back of your
hand and sliding along it with the touch. A hot item will feel faintly as
if its vibrating, whereas the properly grounded item will have no vibration
as the back of the hand is brushed across it.

HOWEVER, if there is even a remote possibility of more than the std 127
volts of AC in the area, I don't recommend it. If the paint has a pinhole,
you can get a quite nasty buzz. In this regard, DC is the much more
dangerous situation as you probably won't feel it until it has a good grip
on you.

IOW, get the sniffer AND learn how to use it, although that part isn't at
all difficult. I don't care if you're flipping burgers at Mac's for
minimum wage, it could save your life.

Something else to consider is that there is a lethal "window" to the
currant passing directly through the heart. It can develop a rhythm loss
and go into fibrillation at currants above 20 micro amperes, a lethal
situation because its just sitting there shaking without moving enough
blood to sustain life. You have maybe 1 long minute to get that fixed else
brain damage is bound to occur. This can happen at currants so low you may
not even feel the shock. And the defib machine paddles will be needed a
very large percentage of the time as its a condition that isn't self
fixing. The shock from the defib paddles works by momentarily freezing the
heart, and when it next beats it will beat in unison with itself. Most of
the time... If not, the techs will let it charge again, and slap you 2x
harder, wash, rinse & repeat until you are either running, or the machine
has hit you with its max jolt quite a few times.

Going up in currant, at currants above 20 milliamperes the heart just
freezes. There, you have that same long minute to remove the shock before
brain damage will set in, but when the currant is removed, the heart
usually starts right back up and goes about its business as if nothing
happened. Typically the major after effects of that will be caring for the
2nd degree burns it causes, and often, because your immune system has been
knocked around pretty badly, a few days later a session of the shingles
will set in for about a 2 month visit. BTDT, ain't no way in hell you
could call _that_ fun.

This sniffer I preach about doesn't work well for high voltage DC, beeping
once or twice as its brought near, and one or 2 times as its pulled away.
The characteristic coaches whistle trill they do is because the AC field is
turning it on and off at 50 or 60 hertz. But high voltage DC isn't
normally a worry for the general public except around high power broadcast
transmitters, some of which use over 20,000 volts.

And TBT, I don't often write this stuff for its entertainment value, it is
supposed to be educational. If I throw in a little humor, its as much to
keep you reading as for the humor in it.

Cheers, Gene
--
"There are four boxes to be used in defense of liberty:
soap, ballot, jury, and ammo. Please use in that order."
-Ed Howdershelt (Author)
My web page: is up!
My views

What about WRITING it first and rationalizing it afterwords? :-)
-- Larry Wall in <8162@jpl-devvax.JPL.NASA.GOV>
A pen in the hand of this president is far more
dangerous than a gun in the hands of 200 million
law-abiding citizens.
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Messages in current thread:
[LAU] Terrible mic ground noise, , (Sun Mar 31, 2:06 pm)
Re: [LAU] Terrible mic ground noise, Len Ovens, (Sun Mar 31, 3:02 pm)
Re: [LAU] Terrible mic ground noise, , (Sun Mar 31, 4:25 pm)
Re: [LAU] Terrible mic ground noise, Len Ovens, (Mon Apr 1, 4:59 am)
Re: [LAU] Terrible mic ground noise, , (Mon Apr 1, 8:14 pm)
Re: [LAU] Terrible mic ground noise, Fons Adriaensen, (Mon Apr 1, 11:06 pm)
Re: [LAU] Terrible mic ground noise, Ralf Mardorf, (Tue Apr 2, 8:44 am)
Re: [LAU] Terrible mic ground noise, Fons Adriaensen, (Tue Apr 2, 10:45 am)
Re: [LAU] Terrible mic ground noise, Ralf Mardorf, (Tue Apr 2, 11:34 am)
Re: [LAU] Terrible mic ground noise, Gene Heskett, (Mon Apr 1, 1:58 pm)
Re: [LAU] Terrible mic ground noise, , (Mon Apr 1, 9:29 pm)
Re: [LAU] Terrible mic ground noise, Gene Heskett, (Tue Apr 2, 12:32 am)
Re: [LAU] Terrible mic ground noise, Ralf Mardorf, (Tue Apr 2, 9:23 am)
Re: [LAU] Terrible mic ground noise, Chris Bannister, (Tue Apr 2, 3:38 pm)
Re: [LAU] Terrible mic ground noise, Len Ovens, (Mon Apr 1, 3:44 pm)
Re: [LAU] Terrible mic ground noise, Fons Adriaensen, (Mon Apr 1, 9:51 am)
Re: [LAU] Terrible mic ground noise, , (Mon Apr 1, 9:14 pm)
Re: [LAU] Terrible mic ground noise, Fons Adriaensen, (Sun Mar 31, 8:25 pm)
Re: [LAU] Terrible mic ground noise, , (Sun Mar 31, 10:05 pm)