Making a Wooden Comp Case, Static Concerns ???

jtice

Flashaholic
Joined
May 21, 2003
Messages
6,331
Location
West Virginia
I am in the middle of a new computer project, involving the use of a wooden case.
I was just wondering if there are any static or electrical concerns I should have.

I never understood why fragile electrical components of a computer are placed in a metal case in teh first place, just doesnt make sence.

But, it has been brought to my attention, that the components of the computer will now not have any common ground.
It this a problem with modern equipment?
Personally, I think killing a computer with static from touching it, is slightly over rated, yes, its possible, but doesnt seem to happen often.

Any tips would be greatly appriciated.

Heres some info on the project.
~~~ Project ECHELON ~~~

~John
 

LukeK

Enlightened
Joined
May 30, 2003
Messages
529
Location
TX
Yeah you aren't going to break a computer with normal amounts of static electricity. What would be much more likely is to damage a stick of ram while transferring it from one PC to another etc. RAM is especially sensitive, while other components are more resiliant. What you could do, is have the motherboard standoffs screw into a metal plate as opposed to the wooden wall of your case, then perhaps ground everything through that (grounding wires or something to that effect). You probably thought of that already, but I figured I'd mention it.
 

Steve K

Flashlight Enthusiast
Joined
Jun 10, 2002
Messages
2,786
Location
Peoria, IL
The reason computers have a metallic housing/case can be summed up in three little letters: "F", "C", and "C".

Digital circuitry is very very fast, and produces lots of high frequency noise. The FCC restricts how much of that noise a device can transmit. The metal housing on the computer keeps all/most of the noise inside, and out of your radios & tv's (and cordless phones and cell phones??).

Static electricity is a concern, but the risks are reduced if you can't physically touch the parts. Mostly, static is a concern when handling the IC's themselves, since most boards are designed to tolerate some static. Even some IC's are intended to tolerate a modest shock or two.

You should also be aware that static electricity poses a hazard other than sudden death. A shock can damage a part so that it fails early, but not immediately.

I'm involved with designing electronics for heavy-duty vehicles, and it has to pass the SAE test for ESD (electrostatic discharge). This involves zapping the device with static charges repeatedly, with up to 15,000 volts! It's not too difficult to design stuff to handle this, but a lot depends on where you can get that spark to hit on the device. A PC should have a much more gentle existance.

good luck,
Steve K.
 

jtice

Flashaholic
Joined
May 21, 2003
Messages
6,331
Location
West Virginia
Thanks for the info guys,

The motherboard will be mounted to a plexiglass sheet, that is positioned in the middle of the case, that plexiglass sheet is attached to a regular rear motherboard panel (the metal part in the back of a computer that holds the PCI cards, etc)

I have thought alittle about the FCC, but I dont know how much of an issue that really is, and how much a case really blocks it.
Todays cases have huge windows taking up most of the sides, that cant be helping any.

Is there any way to block this, short of linning the case in metal?
It is made of 3/4" thick Oak finished Plywood.

~John
 

jtice

Flashaholic
Joined
May 21, 2003
Messages
6,331
Location
West Virginia
.... /ubbthreads/images/graemlins/icon6.gif your lucky im not a moderator Zack /ubbthreads/images/graemlins/twakfl.gif
 

MoonRise

Enlightened
Joined
Feb 9, 2004
Messages
542
Location
NJ
You want the chips on the computer to be protected from outside emissions and so that your computer isn't blasting the area with its own emissions.

It's called EMI (electro-magnetic interference) and a metal 'cage' is the way to do it. Sheet metal or aluminum foil will work, ground the shielding and watch out for gaps and seams. The foil could be easily damaged in handing or servicing things, and grounding it wil be iffy.

You really do need a metal case. It would really be a bummer if you make this wooden case and invest time and money and find out that the computer is wonky because:

you get a call on the house cordless phone;
someone drives past with a cell phone;
there is a cell tower somewhere;
there is a radio station antenna somewhere;
someone with a transmitter (RC, garage door opener, CB, ham, police, taxi, FRS/GMRS, etc) is nearby;
your TV goes wonky when you turn on the computer;
your garage door opener opens all by itself;
etc, etc, etc.

Watch out for outgassing of the plywood or the finish gunking up or corroding things on the computer.

I'd suggest making the wooden box/shell and putting the entire metal-cased computer inside that. Remember to allow for cooling and airflow.
 

Zackerty

Enlightened
Joined
Oct 28, 2004
Messages
386
Location
New Zealand
jtice,
I am sorry, I was being sincere.
I did not read your post before mine clearly enough, as you did say, "short of lining the case in metal"

Stuart /ubbthreads/images/graemlins/crazy.gif
 

DanM

Newly Enlightened
Joined
Sep 2, 2003
Messages
192
Location
MN
Make sure you have good cooling, a wooden case will hold more heat than a metal case.
 

LukeK

Enlightened
Joined
May 30, 2003
Messages
529
Location
TX
[ QUOTE ]
PlayboyJoeShmoe said:
I have seen Plexiglass cases. That can't be exactly as good as metal, and yet big time modders do it...

[/ QUOTE ]

That's a very good point.
 

Lynx_Arc

Flashaholic
Joined
Oct 1, 2004
Messages
11,212
Location
Tulsa,OK
If you want a wooden case the best thing to do is to buy a metal case slightly smaller than the wooden size and use thin wood panels attached to the metal case itself. Removing the front of the case and making a wooden front and keeping the back of it as is for I/O and cooling. The case will appear as wood from all but the back side, but have all the advantages of metal.

One common concern about non metal cases is that processor chips can create radio interference as they do oscillate at high frequencies. I haven't figured out the frequencies but if you listen to short wave I would guess it may be in that range. I used to have a web page that sold wooden cases bookmarked.
 

snakebite

Flashlight Enthusiast
Joined
Mar 17, 2001
Messages
2,721
Location
dayton oh
my neigbor had a lexan cased pc.
i got tired of hearing it on my 2m rig and started pointing a 13b2 that direction and running a 1 kw amp.they put it into a metal case real quick.
i could lock it up at will.
 

Lynx_Arc

Flashaholic
Joined
Oct 1, 2004
Messages
11,212
Location
Tulsa,OK
[ QUOTE ]
snakebite said:
my neigbor had a lexan cased pc.
i got tired of hearing it on my 2m rig and started pointing a 13b2 that direction and running a 1 kw amp.they put it into a metal case real quick.
i could lock it up at will.

[/ QUOTE ]

If that trick would only work on people that play their crummy music too loud in traffic or while driving by....
 

whiskypapa3

Enlightened
Joined
Nov 6, 2002
Messages
475
Location
Western Maryland
Short of lining it with metal? Not hardly.
Snakebite, MoonRise and Zack above have it right. I built one in a wooden case to fit into a bookcase for my wife back in the late 80s, paid much attention to heat removal, noise and RF shielding as it was going in the family area. All I needed for adequate shielding was lining the inside and cover with aluminum foil and ferrite chokes on leads giong to the line, printer and monitor. I could operate my ham gear without any interferance from this computer but could hear any of my other computers and the neighbors on ocassion. As for cooling and noise, large quiet fans worked well, Ran for forteen years as wifey's wordprocessor (until I finally dragged her (kicking and screaming) into the Magical World of Windows).
 

jtice

Flashaholic
Joined
May 21, 2003
Messages
6,331
Location
West Virginia
Stuart, no problem, I was just giving you a hard time /ubbthreads/images/graemlins/wink.gif

Damnit, guys, you have me slightly worried here,,,,

This case will be in a room with a home theater system, 3 monitors, and a TV, not to mention 100 other litte gadgets.

The case is already cut out, and will begin assembly this week,
the side panels have 3 large mindows in each, and the top has a large window, so, im not goning to be able to do much lining.
I dont think there is much sence in me lining what little of the sides and top are left, if there are going to be huge unlined windows.

So... basically, I cant do anything about this, and will just hope it works lol.
I have had trouble in the past with magnetic fields, but not the other things mentioned here.
My last case sat on the floor with both side panels off of it all day.

Is there a way of at leat helping it out, if I cant line it?
I will try to find time to upload the pics of the cutout panels tonight, so you can get more of an idea of how open this case is.

I have noticed that my cell phone can make my home theater system kinda,, make a low tones chirp. But i have to be closer than 5 feet.

~John
 
Top