Archived from groups: alt.comp.hardware.homebuilt (
More info?)
In article <t0q490lilra8tcb48o98deea9o1bo6pbuo@4ax.com>,
donut <donut@glazed.com> wrote:
>if i get the thinner case i can save some money
>but is i going to interfere with the tv reception?
>
>asus a7n266vm
>amd 2000+ xp
>onboard video audio lan
>wd 10gb
>wd 30gb
>mitsumi 3.5
>sony cdrom
>
>On 30 Apr 2004 10:42:38 -0400, adykes@panix.com (Al Dykes) wrote:
I think the answer is that the thinkness of the metal won't make the
difference, other features of the case may. I doubt if you'll
have a problem.
Most of the RF in a PC is in the GHz range, well above the TV bands.
>
>>In article <44tkc.504828$B81.8946718@twister.tampabay.rr.com>,
>>Patrick <pberry26@yahoo.com> wrote:
>>>donut wrote:
>>>> is a computer case with .7mm thickness steel as good as a .8mm?
>>>> is there more emi/rfi in the thinner case?
>>
>>The short answer is No. Is this a general inquery or are you trying
>>to solve a problem ?
>>
>>What are you trying to shield ?
>>
>>Are you trying to prevent interferance from getting in or out ?
>>
>>Frequently interferance gets in or out via the wires you connect to
>>the PC, which is why VGA monitor cables and USB cables frequently hove
>>those lumps on them. If a consmer device causes interferance
>>in can come under FCC regulations.
>>
>>FWIW I have the cover off my desktop PC right now. I just carried
>>an AM/FM radio over to it and tuned the bands. There is a tiny
>>bit of interference what drops to nothing at 6 ft seperation.
>>
>>
>>>In all wires, or metal conductors, electricity follows the "Skin Effect"
>>>in that all electron flow of electricity is in the first molecule of the
>>>outermost skin.
>>
>>To be precice, the Skin Effect is only for alternating current, and it's
>>not "the first molecule. Frequency determines the current density
>>on the crosssection. It's insignificant until you get into the 10's
>>of Mhz.
>>
>>>
>>>The greater flow of a #4 guage wire, over a #14 guage wire is due to the
>>>vastly greater skin area of the #4 wire.
>>
>>
>>
>>>
>>>If we are dealing with a flat area, there is no significant difference
>>>between a 10 guage steel sheet, and a 6 guage steel sheet, provided they
>>>are both used predominately in their flat sheet shape!
>>>
>>>We often use screen mesh, in blocking EMI/RFI, and you might see
>>>multiple layers of screen, folded, used as a gasket, in some computers
>>>from the 1980's. The screen may permit emission of some higher
>>>frequency energy.
>>>
>>>In fact, if you examine your Microwave Oven, you will see the 'screen'
>>>of punched holes in the door window, where the holes are smaller than
>>>the wavelength of the tuned microwave frequency, effectively blocking
>>>it, while allowing visual range 'light' frequencies to pass!
>>>
>>>
>
--
Al Dykes
-----------
adykes at p a n i x . c o m