Author Topic: Faraday Cage? (Read 4860 times)

FrizzleFried · « **on:** February 16, 2007, 06:01:13 pm »

Anyone know of a simple, inexpensive way to create a Faraday Cage? I am having a problem with one of my cabs EFI...when I run the damn thing, my garage door doesn't work VIA remote. My neighbors garage door doesn't work via remote. My 3 neighbors across the street's garage doors don't work with their remotes. My remote for my ceiling fans don't work. My keyless entry and my wifes keyless entry for our vehicles don't work.

I have tested by driving the car in 10 feet or so increments and believe it or not, it takes about 50 FRIGGIN' YARDS before the damn keyless entry will work!

I turn off the cab, all works fine.

I've swapped CPUS, hard drive, etc...no luck. It's the motherboard for sure. I need to block this EFI...my neighbors get quite pissed off when they come home and can't open their garage doors!

HELP!

Jeff AMN · « **Reply #1 on:** February 16, 2007, 06:04:30 pm »

Holy smokes, are you powering that thing with nuclear energy or what? I've never heard of such a crazy thing.

FrizzleFried · « **Reply #2 on:** February 16, 2007, 06:07:23 pm »

It's a Gigabyte Nforce 3 motherboard...powering an Athlon 3200. At first I thought it may be because of my overclock...but even at stock speed...same problem.

I am afraid of what it may do to the poor old dude with a pacemaker who may walk down my street!

Jeff AMN · « **Reply #3 on:** February 16, 2007, 06:08:14 pm »

Do you have to press a button every 180 minutes like they do in Lost?

RandyT · « **Reply #4 on:** February 16, 2007, 06:12:52 pm »

Just out of curiousity, any odd controls on your cabinet? Weird HV lighting? Anything attached with long wiring that might act like an antenna?

Have you tried powering down / disconnecting everything but the computer to make sure you aren't barking up the wrong tree?

RandyT

GoPodular.com · « **Reply #5 on:** February 16, 2007, 06:34:23 pm »

Microwave oven = faraday cage.

Something is wrong if it's doing that. By design, PC's are supposed to be the victim of EMI, not a producer. They fall under the Class B section of the FCC. They're tested inside of a case though.

Here's what I'd try:
1- First, try plugging into a different circuit of the house.
2- Then try the PC inside a case.
3- Check if it's a combination of PC+marquee light, or something.

It'll probably be cheaper to fix the problem then try and compensate for it.

Kevin Mullins · « **Reply #6 on:** February 16, 2007, 07:27:33 pm »

Do you have anything "wireless" running in your cab?

That would be the only thing actually "producing" a signal of any kind.

FrizzleFried · « **Reply #7 on:** February 16, 2007, 07:42:03 pm »

Nope nope and nope. I am 100% certain it is the PC. Why may you ask? Because this is the motherboard that I stopped using in my main PC rig a year ago before I got in to MAME....why did I stop? Because it was causing my garage door to not open in my condo. At the time though, my computer was RIGHT ABOVE (we lived above the garage) the garage door opening...I had no idea the problem extended so far.

I have no wireless devices hooked up to it. Only a CPU, RAM, and HD. Hell, I don't even use a separate sound card. I have tried swapping CPUS to no avail. It IS the motherboard producing this problem...I am certain of it. I will try to put the MB in a PC case and see if that will block the EMI (EFI?). If that doesn't work, I guess I will be in the market for another AMD 939 motherboard.

johnm160 · « **Reply #8 on:** February 16, 2007, 07:59:08 pm »

I saw an episode of mythbusters where they used a copper mesh wire that looked like chicken wire stapled to a wooden frame to make a Faraday Cage.

I have also read that you can use mylar space blankets. That might be a quick and easy test. Toss a space blanket over the motherboard and see what happens.

CheffoJeffo · « **Reply #9 on:** February 16, 2007, 08:10:47 pm »

Quote from: FrizzleFried on February 16, 2007, 07:42:03 pm

Nope nope and nope. I am 100% certain it is the PC. Why may you ask? Because this is the motherboard that I stopped using in my main PC rig a year ago before I got in to MAME....why did I stop? Because it was causing my garage door to not open in my condo. At the time though, my computer was RIGHT ABOVE (we lived above the garage) the garage door opening...I had no idea the problem extended so far.

Let me get this straight, you took a motherboard that was causing your garage door not to open and put it in a cab in your garage?

You GOTTA be working for NASA!

FrizzleFried · « **Reply #10 on:** February 16, 2007, 08:34:29 pm »

Quote from: CheffoJeffo on February 16, 2007, 08:10:47 pm

Quote from: FrizzleFried on February 16, 2007, 07:42:03 pm
Nope nope and nope. I am 100% certain it is the PC. Why may you ask? Because this is the motherboard that I stopped using in my main PC rig a year ago before I got in to MAME....why did I stop? Because it was causing my garage door to not open in my condo. At the time though, my computer was RIGHT ABOVE (we lived above the garage) the garage door opening...I had no idea the problem extended so far.

Let me get this straight, you took a motherboard that was causing your garage door not to open and put it in a cab in your garage?

You GOTTA be working for NASA!

Hahahahaha...I don't use my garage door opener and wasn't aware of how far reaching the problem was. But yes...I am a genius!

CheffoJeffo · « **Reply #11 on:** February 16, 2007, 08:52:08 pm »

SOOPER GENIUS!

fjl · « **Reply #12 on:** February 16, 2007, 10:06:55 pm »

Enclose the mobo in aluminum foil.

Tailgunner · « **Reply #13 on:** February 17, 2007, 12:47:07 am »

I'd tend to think the power supply was a more likely culprit, but anything is possible.

One of my dedicated cabs has a foil covered cardboard box that the the PCB is mounted inside of.

leapinlew · « **Reply #14 on:** February 17, 2007, 01:06:25 am »

Quote from: FrizzleFried on February 16, 2007, 07:42:03 pm

It IS the motherboard producing this problem...I am certain of it.

Sounds like a shlemiel field to me. I can't wait to hear how this one turns out.

johnperkins21 · « **Reply #15 on:** February 17, 2007, 01:09:44 am »

Quote from: leapinlew on February 17, 2007, 01:06:25 am

Quote from: FrizzleFried on February 16, 2007, 07:42:03 pm
It IS the motherboard producing this problem...I am certain of it.

Sounds like a shlemiel field to me. I can't wait to hear how this one turns out.

It could be a shlimazl field as well. But that's just what my friend LaVerne suggested.

GoPodular.com · « **Reply #16 on:** February 17, 2007, 02:13:39 am »

I was thinking about this today and don't those anti-static bags you get electronics equipment in operate just like faraday cages? Might be able to put the mobo in a case and then cover the case with some of them taped together. You'll have to pipe in some fresh air for the fans though.

JustMichael · « **Reply #17 on:** February 17, 2007, 04:40:45 am »

FrizzleFried, do you happen to live on or near a military base? The reason I ask is that a lot of the frequencies that garage door openers use has been allocated to the military now by the FCC.

daywane · « **Reply #18 on:** February 17, 2007, 06:59:56 am »

you can send the cab to me.
My house is on a slab foundation, and made of cinder blocks, and stucco over that

I can not get a signal into my house let along one out.

SavannahLion · « **Reply #19 on:** February 17, 2007, 10:28:17 am »

You have to have a case in order for a motherboard to qualify as an FCC Class B device. Those cutaway side panel with plexiglass windows or those whole plexiglass cases don't pass FCC testing, so don't bother using them.

This paper has a nice description on how to handle and reduce EMI fields http://www.amd.com/us-en/assets/content_type/white_papers_and_tech_docs/26003.pdf
It points out some details even I wasn't aware of. Such as it's the length of the gap in the case not the width that causes problems and grounding heat sinks.

FrizzleFried · « **Reply #20 on:** February 17, 2007, 10:33:51 am »

Quote from: JustMichael on February 17, 2007, 04:40:45 am

FrizzleFried, do you happen to live on or near a military base? The reason I ask is that a lot of the frequencies that garage door openers use has been allocated to the military now by the FCC.

Nope...closest base is in Mountain Home some 40-50 miles away. This issue also happened in San Diego, but I WAS much closer to a military base there (15 miles or so).

FrizzleFried · « **Reply #21 on:** February 17, 2007, 10:35:11 am »

Quote from: SavannahLion on February 17, 2007, 10:28:17 am

You have to have a case in order for a motherboard to qualify as an FCC Class B device. Those cutaway side panel with plexiglass windows or those whole plexiglass cases don't pass FCC testing, so don't bother using them.

This paper has a nice description on how to handle and reduce EMI fields http://www.amd.com/us-en/assets/content_type/white_papers_and_tech_docs/26003.pdf
It points out some details even I wasn't aware of. Such as it's the length of the gap in the case not the width that causes problems and grounding heat sinks.

Thank you VERY much...this info is EXACTLY what I was looking for. I will report my results when I get a chance to work on that cab....

fixedpigs · « **Reply #22 on:** February 17, 2007, 11:28:48 am »

Quote from: FrizzleFried on February 17, 2007, 10:33:51 am

Nope...closest base is in Mountain Home some 40-50 miles away. This issue also happened in San Diego, but I WAS much closer to a military base there (15 miles or so).

heh...i used to live at mountain home afb back in '84-'86...!

this whole emi thread is very interesting...i never knew...

here's a couple of questions...
when should i be concerned about this...?
how do i know if it's a problem...?

FrizzleFried · « **Reply #23 on:** February 17, 2007, 12:00:20 pm »

Quote from: fixedpigs on February 17, 2007, 11:28:48 am

Quote from: FrizzleFried on February 17, 2007, 10:33:51 am
Nope...closest base is in Mountain Home some 40-50 miles away. This issue also happened in San Diego, but I WAS much closer to a military base there (15 miles or so).

heh...i used to live at mountain home afb back in '84-'86...!

this whole emi thread is very interesting...i never knew...

here's a couple of questions...
when should i be concerned about this...?
how do i know if it's a problem...?

I just picked up my Basset Hound puppy from the base (well, just outside of the base)...

I found out it was a problem when I couldn't open my garage door when my PC was on. I became concerned about it when my NEIGHBORS couldn't open THEIR garage doors when the PC was on.

tikbalang · « **Reply #24 on:** February 17, 2007, 01:12:34 pm »

try enabling "spread spectrum" in the bios. this is supposed to reduce emi.

FrizzleFried · « **Reply #25 on:** February 17, 2007, 02:38:20 pm »

Tried it before...no go.

<sigh>

Havok · « **Reply #26 on:** February 17, 2007, 02:43:55 pm »

Man, I would be more concerned about your exposure to this EMI than a stupid garage door opener problem. If you're convinced it's the motherboard, try another motherboard and see if that resolves the problem. I have an AMD motherboard mounted in my cab - no case, and we have wireless internet, cordless phones, etc and no problems. I can't believe that a modern mobo is the cause - there must be something wrong with the PSU, that would be the more likely culprit in my mind...

FrizzleFried · « **Reply #27 on:** February 17, 2007, 02:56:43 pm »

Quote from: Havok on February 17, 2007, 02:43:55 pm

Man, I would be more concerned about your exposure to this EMI than a stupid garage door opener problem. If you're convinced it's the motherboard, try another motherboard and see if that resolves the problem. I have an AMD motherboard mounted in my cab - no case, and we have wireless internet, cordless phones, etc and no problems. I can't believe that a modern mobo is the cause - there must be something wrong with the PSU, that would be the more likely culprit in my mind...

Nope...not the PSU...as it is a different PSU than when I was having problems in San Diego. That PSU is still in my main PC in my bedroom. I too have MULTIPLE computers running fully exposed without any issue. It is very strange indeed. It's also strange that it effects ONLY wireless garage door remotes, keyless entry remotes, etc. No issues with any radios, TVs, monitors, or any other devices when the cab is running.

I am going to try a few things to block the EMF...if they fail, it's time for a new motherboard. For now I am unable to run the damn cabinet until late at night in fear of my neighbor coming over bitching she/he can't get in the garage again.

Kevin Mullins · « **Reply #28 on:** February 17, 2007, 03:04:04 pm »

Quote

For now I am unable to run the damn cabinet until late at night in fear of my neighbor coming over bitching she/he can't get in the garage again.

So your neighbors already know you are the cause?
Bummer....

I still can't fathom a PC motherboard or a particular component installed on it producing THAT much interference.

FrizzleFried · « **Reply #29 on:** February 17, 2007, 03:22:18 pm »

Quote from: Kevin Mullins on February 17, 2007, 03:04:04 pm

Quote
For now I am unable to run the damn cabinet until late at night in fear of my neighbor coming over bitching she/he can't get in the garage again.

So your neighbors already know you are the cause?
Bummer....

I still can't fathom a PC motherboard or a particular component installed on it producing THAT much interference.

Yah...I made the mistake of letting my next door neighbor know what was going on when I saw him out messing with his garage door opener. That was when i realized the effect was so broad and started doing tests. PC on, no work... PC off, work.

It sure is friggin' strange (and quite a pain in the ass).

SavannahLion · « **Reply #30 on:** February 17, 2007, 05:54:36 pm »

Quote from: Havok on February 17, 2007, 02:43:55 pm

Man, I would be more concerned about your exposure to this EMI than a stupid garage door opener problem.

Given that our daily lives are swamped in a sea of EMI radiation, an errant motherboard is hardly going to be cause for concern. The constant pounding we receive from our cell phones and our WiFi access points probably cause more cell mutations.

grundle · « **Reply #31 on:** February 19, 2007, 09:35:23 am »

I actually registered just to reply to this...I actually design electronics enclosures for work and one of our biggest concerns is EMI (electro magnetic interference.)

First, Make sure everything has a common ground point. What I would do is run wire from the power supply chassis to a mounting point on the motherboard and any other boards in there that aren't plugged to the motherboard directly. This should help a lot.

If this isn't enough, there are some paint on EMI shields that you could paint the inside of the cab with. Wood doesn't block anything...
http://www.lessemf.com/paint.html

Good luck!

SavannahLion · « **Reply #32 on:** February 19, 2007, 10:35:40 am »

HOLY SMOKES!!! $159.95 for a quart of the stuff?

Wouldn't it be way cheaper and just as effective to line the insides with copper mesh or some sort of metal sheeting? You would have to ensure contact between moveable panels such as the door anyways, so you might as well tackle it then.

Hi, welcome to the forums!

Teebor · « **Reply #33 on:** February 19, 2007, 11:02:09 am »

Is the computer actually inside a case?? as said somewhere above the case has to meet or exceed certain regulations and that on its own should cut down any EMI produced at all. (or at least spare your neighbours some headache)

Otherwise tin foil can work but make sure that it is grounded to the power supply or some other earth.

Are you sure that any power strips are earthed properly?

on a side note changing the Spread Spectrum in the BIOS is meant to help the motherboard to resist interference produced by any nearby sources or itself :/

grundle · « **Reply #34 on:** February 19, 2007, 11:23:59 am »

I've used the spray paint...$25 for a can (partway down the page.). Admittedly, I wasn't paying, it was for work.

Thanks for the welcome, I hope to be building a cab in the next few months...

Quote from: SavannahLion on February 19, 2007, 10:35:40 am

HOLY SMOKES!!! $159.95 for a quart of the stuff?

Wouldn't it be way cheaper and just as effective to line the insides with copper mesh or some sort of metal sheeting? You would have to ensure contact between moveable panels such as the door anyways, so you might as well tackle it then.

Hi, welcome to the forums!

xmenxmen · « **Reply #35 on:** February 19, 2007, 01:21:38 pm »

Ever tried contacting Gigabyte to see if they will exchange it for you. Generally if a manufacturer cares even a bit, they will take care of U especially when it comes to these type of problems. Give tech support a call even if it's not under warranty.....

Otherwise, throw it out, cheaper to replace the motherboard then then make all the changes to try to eliminate the EMI.

Crowquill · « **Reply #36 on:** February 20, 2007, 11:53:34 am »

Quote from: xmenxmen on February 19, 2007, 01:21:38 pm

Ever tried contacting Gigabyte to see if they will exchange it for you. Generally if a manufacturer cares even a bit, they will take care of U especially when it comes to these type of problems. Give tech support a call even if it's not under warranty.....

Otherwise, throw it out, cheaper to replace the motherboard then then make all the changes to try to eliminate the EMI.

Right. They may swap you a motherboard just to have yours to research the problem. I don't know that much about wireless frequencies, but it seems like with all the different types of devices affected that it would be interfering with devices using a range of frequencies. Very odd indeed.

Just the fact that it causes this much interference would cause me to search out a new mobo. I think I'd definitely get a different model if not one from a different manufacturer.

danny_galaga · « **Reply #37 on:** February 21, 2007, 06:57:33 am »

i have it on good authority that a faraday cage made of aluminium foil, and roughly conical in shape placed on your head will stop these problems. please post pic when you are successful (",)

Teebor · « **Reply #38 on:** February 21, 2007, 08:14:36 am »

ALIENS!!!!!!!!!!!!!!!!!!!!!!! ALIENS!!!!!!!!!!!!!!!

FrizzleFried · « **Reply #39 on:** February 21, 2007, 09:54:46 am »

I think I may go the "talk to Gigabyte" route. If that fails, I'll likely replace the motherboard. But who knows, tinfoil hats have worked in the past for the alien cat problem I was experiencing back In San Diego. Damn KittyBorg were everwhere.


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