General ESD info

I'm mainly starting this thread for another but don't want to fill it up with this. Also I figured others might find it interesting.

Here is a link to a site with instructions to make a homemade electrostatic voltage detector. It uses a fairly common audio transistor to pick these voltages out of the air. The transistor is made to respond to voltages from 9-25 volts but I found that it would pick up the static charge in the foot prints I made in my carpet from up to a foot away. It could pick this voltage in my foot prints (from walking normally on it) for up to five minutes after I made them.

Some random info on ESD:

Normal means of static generation and electrostatic voltages at relative humidity ranging from 10-20% to 65-90%

Walking across carpet
At 10-20% 35,000
At 65-95% 1,500

Walking over a vinyl floor
At 10-20% 12,000
At 65-95% 250

Moving at a desk
At 10-20% 6,000
At 65-95% 100

Opening vinyl sleeving
At 10-20% 7,000
At 65-95% 600

Picking up poly bag from a desk
At 10-20% 20,000
At 65-95% 1,200

Someone sliding in a polyurethane foam padded chair
At 10-20% 18,000
At 65-95% 1,500

This shows that electrostatic voltages can reach extreme levels under the right conditions, and also shows why most components come in ESD bags. If the above is true just imagine the charge that could be built from a component packed ontop of foam sliding back and forth against the card board box during shipping that could be generated!

ESD from a human to a material or through an electronic device can posses current values from 1 to 50 amps with a rise time from .5 to 20 nanoseconds. This discharge will be measured in milliwatts but still today’s electronic circuitry can withstand only a fraction of this amount of power.

ESD at a level as low as 25 volts can destroy most of the micro-circuitry in a home computer and it takes a discharge of up to 3,500 for the average person to even notice it. This means that most ESD mishaps will occur without the handler even noticing the discharge.

This being said compare this to some of the electronics we work (play) with.

Average processor: 1-1.8 volts (stock)
DDR RAM: 2.5-2.85
PCI: 3.3V/5V
AGP: 3.3v was agp 1.0 (2x), 1.5v was agp 2.0 (4x), .8v is agp 3.0 (8x)

This being said, what percentage of PC parts are DOA, or RMA'd after a component died during a home installed upgrade? Don't know but it's probably pretty high.
Will an ESD mishap occur even 10% of the time you work with something? No, probably not, but it is something to take into consideration when you are about to handle computer components. Just remember to ground yourself and you'll be fine. Many tech manuals will recommend an ESD wrist strap but if this is not available putting a hand on your computer case should work. I'd imagine it's what's kept most people out of trouble (including myself). After making the ESD detector from the link at the start of this thread I turned it on and immediately the LED came on. I could only hold it and detect electrostatic voltages around me by first grounding myself out which was usually done by touching my computer case which was grounded by the plug to the wall outlet.

Just some random info to think about. Let me know if you find any inaccuracies and I'll fix them first chance I get.

Edit- So far just fixed grammer and spelling.

Bump for still relevant information.

Oh yeah, something I forgot to put in the original post.... 2 and a half years ago.

Just because an outlet is a three prong outlet doesn't mean the ground is hooked up. The last owner (or current if you rent) might have just upgraded the outlet without upgrading the wiring.... for looks.

If air is pushed over an object, the object can pull electrons from the air and build up a static charge. This can be rare to encounter, but it does happen. This is why there are regulations stating that pressurized containers holding a flammable gas or liquid should be grounded when in use. Actually, this is also a big reason that many will recommend against using a vacuum cleaner in side a computer. You might get away with it, but there still is a chance; why take it?

At any rate, computers today mean air movement for cooling. If they're not grounded they can and probably will build up an electrical charge. They will operate fine with this charge. However, if it's holding a charge, you're not, and you touch lets say the RAM, there's a fair chance that you'll end up with dead RAM. This also holds true if you add a component while the case has a charge.

I wont go into the other negative effects of the a computer holding a charge; the point is, if a computer shocks you when you touch it, take a moment to assess the the situation before you proceed. You might look into finding another outlet or ensuring that you and the case are at the same potential before you do any work on it.

I only add this now as I had this exact problem. I'd edit the above to state current operating voltages in Processors, RAM, and PCI-E, but the important thing to see is the scale of difference between what you can generate, and what modern equipment roughly runs at. It doesn't matter if it's a 1v or a 12v circuit. Chances are that 25v+ will at the very least shorten it's life span and most likely kill it.