Building a Faraday's cage ?

[John Larkin]

"John Larkin"


You were a born pedantic, autistic IDIOT - Larkin.

Well, if I was born that way, I can't help it, can I? So I may as well
relax and go with it. And (just to be pedantic) I'm bipolar, not
autistic.

When you die is the only time that will change.

Gotta hand it to you there!

Hope for the sake of humanity it is real soon.

It sure sounds like you need a break, to get away from things and
relax a little.

Really, all that anger will kill you a lot faster than having fun will
kill me. And if you intend to be angry for the rest of your life,
you're sort of dead already.

John

 

[Phil Allison]

"John Larkin Congenital Fuckwit "

And (just to be pedantic) I'm bipolar, not autistic.

** So John Larkin is an admitted Manic / Depressive as well as
congenitally autistic.


Head shrinkers never reveal the full extent of a patient condition - even
to them.

Professional ethics - "do no harm".

To their patient that is.

**** the rest of society.







...... Phil

 

[Jim Thompson]

Well, if I was born that way, I can't help it, can I? So I may as well
relax and go with it. And (just to be pedantic) I'm bipolar, not
autistic.


Gotta hand it to you there!


It sure sounds like you need a break, to get away from things and
relax a little.

Really, all that anger will kill you a lot faster than having fun will
kill me. And if you intend to be angry for the rest of your life,
you're sort of dead already.

John

As one with an autistic grandson I resent Phil's rants... BIG TIME!

I guess I'm a bit slow, I should have realized before that there's a
really simple solution to disposing of Phil.

I'll have the Autism Society here in Phoenix contact its counterpart
in OZ.

Since parents and grandparents of autistic children have rather strong
feelings about autism, it wouldn't surprise me if there wasn't an
attitude-adjusting "visitation" right away ;-)

...Jim Thompson

 

[John Larkin]

"John Larkin Congenital Fuckwit "





** So John Larkin is an admitted Manic / Depressive as well as
congenitally autistic.

I freely acknowledge the bipolar part, "know thyself" and all that,
but I'm certainly not autistic... I'm too empathic, if anything. My
wife is a speech pathologist and works with autistic kids daily, so
she would know. We do have a common interest in the possible causes of
autism, including the geek-mating effect, about which I posted a link
recently.

**** the rest of society.

Tall order.

John

 

[John Larkin]

As one with an autistic grandson I resent Phil's rants... BIG TIME!

It's not logical to me to insult people for what they are... autistic,
stupid, black, gay, female, any of that.

I guess I'm a bit slow, I should have realized before that there's a
really simple solution to disposing of Phil.

What Phil really needs is for somebody to kidnap him and show him a
good time.

John

 

[Jim Thompson]

It's not logical to me to insult people for what they are... autistic,
stupid, black, gay, female, any of that.


What Phil really needs is for somebody to kidnap him and show him a
good time.

John

Yes, a gang gay rape should do the trick ;-)

...Jim Thompson

 

[Phil Allison]

"John Larkin Congenital Fuckwit "

I freely acknowledge the bipolar part, "know thyself" and all that,
but I'm certainly not autistic.

** Well, you would say that wouldn't you.

.. I'm too empathic, if anything. My
wife is a speech pathologist and works with autistic kids daily, so
she would know.

** What pathetic drivel.





....... Phil

 

[John Larkin]

** What pathetic drivel.

She's not pathetic, she's nearly the ideal woman: smart, skinny,
funny, feminine, and makes a lot of money. If you had a woman this
good, you wouldn't be so crabby. Or vice versa. Whatever.

John

 

[Phil Allison]

"John Larkin"

She's not pathetic, she's nearly the ideal woman: smart, skinny,
funny, feminine, and makes a lot of money. If you had a woman this
good, you wouldn't be so crabby. Or vice versa. Whatever.

** Snipping and posting irrelevant responses is CLASSIC autistic behaviour.

Doing that same thing over and over is even more classis.

QED.




........ Phil

 

[Ken Smith]

I'm a complete ignorant in this matter - can you please explain why two not
one and what material and how thick (copper is pretty expensive here) ?[/QUOTE]

Per inch, aluminum is only twice as bad as copper but way less expensive.
Per pound it is better than copper.

If you are having problems with 60Hz, I wouldn't use either. Magnetic
materials like iron do way better.

I seriously doubt the claim of 150dB with two layers of iron. If that
was true there wouldn't be a market for 6 layer shield cans.

How thick ?

If this is a home project, I'd use thin "tin plate". Tin plate is tin
plated iron. You can hook it together by soldering.

You may want two layers with a spacer between.

To see why work out the ouput voltage for these two circuits:

--the air ---
100K 1K
100V ---/\/\---/\/\----+----+---- Out
! !
\ \
1.0 / / 1.0 <- the iron
\ \
! !
GND GND


Vout = 100 * 0.5/(101K + 0.5) = 0.5mV (Near enough)



100K 1K
100V ---/\/\-----+--/\/\--+---- Out
! !
\ \
1.0 / / 1.0
\ \
! !
GND GND


Work out the combined resistance of 3 on the right:

Ra = 1.0 * (1000 + 1.0) / (1.0 + 1000 + 1.0) = 0.999

Vout = 100 * (1.0/(1000+1.0)) * Ra /(100K + Ra) = 1uV near enough

Note how arranging the same parts in the second way make the signal much
lower. It works that way with magnetic materials.

 

[Phil Allison]

"Ken Smith"

If this is a home project, I'd use thin "tin plate".

** Laughable nonsense.

Tin plate is a completely ineffective magnetic shield.


Did you read the OP's original idea at all?

" I'm planning to build a 2m x 2m Faraday's cage/booth to protect active
electric guitar pickups from external electrostatic and electromagnetic
noise 20hz-96khz "

The booth is the size of a toilet cubicle intended for a guitarist to sit in
while he plays .


The OP is deluded plus has grossly exaggerated the hum problem.




........ Phil

 

[Ken Smith]

It clearly has a big effect on power wires in my walls - i can hear a loud
noise if i put my emg707 very close to a wire in my wall and that noise gets
much quieter if i turn my guitar 180 degrees to face away from the wall and
hold the pickup at the same distance to the wire.[/QUOTE]

That sounds like electrostatic pick up is at least part of the problem.
In the classic magnetic case, the signal nulls at 90 degrees and is
inverted at 180.

 

[Ken Smith]

In the USAF, in avionics, they were routine. At one base where I worked,
the whole shop was a screen room, (which they called 'shield room') to the
extent that they used incandescent lights and the air conditioning was
woefully inadequate. The wall paneling, ceiling, and floor were sheet
metal.

It was pretty quiet (electrically), however.

Now you can get the first bit of AC power shielding from a system with
magnetic sensors and bucking coils. They don't spec. the noise however.

 

[Ken Smith]

"Ken Smith"



** Laughable nonsense.

Tin plate is a completely ineffective magnetic shield.

That is simply false. Tin plate I've tried was magnetic enough to provide
shielding.

Did you read the OP's original idea at all?

" I'm planning to build a 2m x 2m Faraday's cage/booth to protect active
electric guitar pickups from external electrostatic and electromagnetic
noise 20hz-96khz "

The booth is the size of a toilet cubicle intended for a guitarist to sit in
while he plays .

So, that is what he is planning on doing. If he was building one the size
of a coffin it wouldn't have changed the answer.

 

[Phil Allison]

"Ken Smith"

That is simply false.

** It is completely true.

Tin plate I've tried was magnetic enough to provide
shielding.

** Bollocks !!!

Magnetic shielding requires special materials, like Mu-metal.

What do you think is used around CRTs inside scopes and for microphone
transformers ?

Tin plate ??????

So, that is what he is planning on doing. If he was building one the size
of a coffin it wouldn't have changed the answer.

** So says an asinine, posturing fool.





........ Phil

 

[Phil Allison]

"Ken Smith"

That sounds like electrostatic pick up is at least part of the problem.

** Those "emg" pickups are dual coil magnetic - you ass.

Look them up .




........ Phil

 

[Ken Smith]

"Ken Smith"


** It is completely true.

It was false when you first posted it and it remains false.

** Bollocks !!!

Magnetic shielding requires special materials, like Mu-metal.

This is also simply not true. Any material that has a mu greater than
free space will act as a shield. The higher the mu the better, provided
it does not saturate.

Even fairly open structures like the body of a car, reduces the amplitude
of the AC field seen inside.

 

[Ken Smith]

"Ken Smith"




** Those "emg" pickups are dual coil magnetic - you ass.

And you claim this explains the 180 degrees exactly how?

A dual coil pick up will still have its minimum and maximum at 90 degrees
to each other unless you are claiming that the OP removed the strings and
dug into the wall to make the distances small enough.

 

[Phil Allison]

"Ken Smith Sniping Lying Fuckwit "

It was false when you first posted it and it remains false.

** This asinine Smith fool has no bloody idea.

This is also simply not true.

** The ASININE snipping Smith Fuckwit has no case.

" What do you think is used around CRTs inside scopes and for microphone
transformers ? "

Any material that has a mu greater than
free space will act as a shield.

** Supposition - not fact.

Do some real tests.

Do a simple Google Search.

Or go get totally fucked you


PITA DAMN LIAR !!!





......... Phil

 

[Phil Allison]

"Ken Smith PITA Fucking Moron "


** Those "emg" pickups are dual coil magnetic - you ass.

Look them up YOU FUCKING IDIOT !!!!


The OP's story is a total crock of SHIT.






......... Phil