Another Static Electricity Question...

[Super TWiT]

What I was wondering about was why can't you have your wrist strap clipped to your case, but just not have it plugged in. Electrons would just build on the case right? If so, what's the problem with that?

[guest7146]

By the way, if anyone has any doubts about the damage that can be caused by static electricity try the following:

1. Set up a simple CMOS IC based circuit on breadboard.  A simple binary counter circuit or something like that.  You'll find such circuits in any beginner's electronics book.

2. Check the circuit to make sure it works.

3.Take the CMOS counter IC out of the circuit.

4. Find yourself some wooly clothing and build a static charge on yourself by rubbing the clothing together.  Alternatively you can rub your hands over an old CRT monitor while you switch it on from cold.

5. Once you've built up a nice static charge, touch one finger onto the CMOS IC.

6. Plug the IC back into your previously working circuit.  My guess is, it'll be dead as a door nail.  This is an extreme case where you've purposely built up a big static charge on yourself and immediately discharged it through an IC.  But there are many "in-between" states where you'll have inadvertently built up a charge on yourself and you compromise the device you handle instead.  It's this case that shows no immediate symptoms but reduces the life span of the device.

AH.

[Super TWiT]

I don't doubt static electricity is dangerous. I just wondered what the problem was if I didn't plug in the computer to ground while I worked on it, but had my wrist strap clipped to the case. Even though the case isn't grounded, all that would happen is electrons would build up on the case right? Where's the harm in that? They would dissipate the next time I plugged the computer into a grounded outlet.

[koaftder]

I don't doubt static electricity is dangerous. I just wondered what the problem was if I didn't plug in the computer to ground while I worked on it, but had my wrist strap clipped to the case. Even though the case isn't grounded, all that would happen is electrons would build up on the case right? Where's the harm in that? They would dissipate the next time I plugged the computer into a grounded outlet.

Electricity just wants to follow the path of least resistance to ground. The safest thing to do is just ground everything which in this case is you and the machine.

[Buzzfuzz]

I just have a power cord with only ground wire in it and this goes into the PSU and the other end in the wall socket which in the entire house are all grounded.
I keep one hand on the case when I insert or take out a card and I haven't blown any of my own.
I have however blown a videocard in the early days on the pc of one of my friends with static.
He reteurned it and got a new one :roflmao:
 
On the Amiga the 1084 monitor is one of the main reasons for blowing Amiga's since this is only uses live and neutral and is not grounded.
And when you connect the RGB connector to your Amiga while the monitor is on you can probably see little sparks when it touches the video connector on the Amiga.

[Boudicca]

Static is serious...but..only if you are handling devices that are not "buffered", since tri-state buffering 99% of IC's arent "that" static sensitive.

Just make sure you keep the IC's in tin foil wrapped polystyrene or proper anti-static bags or conductive foam. Handle with care and ground the chip on the case or keep it in-socket and all will be well.

There is really, No need for straps or other crazy mats or stuff. Your more likely to break the pins or bend them the wrong way, because your wrist strap snags on a case

[xyzzy]

One small point, if you're going to ground yourself to a low-impedance source, like mains earth or a metal case, then do it through a high-value resistor, so that if you do accidentally touch a high-voltage circuit you don't end up fried.

Even better, use one of these:

http://en.wikipedia.org/wiki/Antistatic_wrist_strap

[Boudicca]

then do it through a high-value resistor

U have shoes don't u ?

If you are planning to commit suicide by electricity, and earth strap isn't going to stop that.

Your more likely decrease your resistance and conduct across from hand to hand through the heart. Smokin.....

Warning: For Education purposes only. Do not watch if you a minor ! Just google it later.
http://www.liveleak.com/view?i=fc0_1243424473

[motrucker]

One small point, if you're going to ground yourself to a low-impedance source, like mains earth or a metal case, then do it through a high-value resistor, so that if you do accidentally touch a high-voltage circuit you don't end up fried.

Even better, use one of these:

http://en.wikipedia.org/wiki/Antistatic_wrist_strap

Never seen a commercial wrist strap that didn't incorporate a resistor in it.  Not really for your worry though...

[Framiga]

other what already said, pay attention on what you are dressing while doing services (electronics services i mean:-))

On a side note, consider that if you are working in a known/safe enviroment (like your own bench) is a matter while if you are out for servicing fe a server or such, in an unknown enviroment (at least for you) is all another matter (above all the gears you working on, are not yours)  :-)

[Daedalus]

Static is serious...but..only if you are handling devices that are not "buffered", since tri-state buffering 99% of IC's arent "that" static sensitive.

Just make sure you keep the IC's in tin foil wrapped polystyrene or proper anti-static bags or conductive foam. Handle with care and ground the chip on the case or keep it in-socket and all will be well.

There is really, No need for straps or other crazy mats or stuff. Your more likely to break the pins or bend them the wrong way, because your wrist strap snags on a case

If you ground the chip on the case, then touch the pins with your fingers you can still destroy it. What good is grounding the chip? The chip isn't where the static is, you are! And tri-state outputs are still semiconductor driven, and can still break down very quickly when their maximum voltage is exceeded. And static is well beyond their rated maximum.

To answer the other question, if you and the case are at the same potential, i.e. you're connected to the case with a strap, then the static is not going to be a problem unless the chip or whatever comes near to contact with an actual ground while you're touching it - which is probably unlikely. It greatly reduces the risk, but to be sure you're still better off having the case and yourself grounded.

[gertsy]

I just have a power cord with only ground wire in it and this goes into the PSU and the other end in the wall socket which in the entire house are all grounded.
I keep one hand on the case when I insert or take out a card and I haven't blown any of my own.
I have however blown a videocard in the early days on the pc of one of my friends with static.
He reteurned it and got a new one :roflmao:
 
On the Amiga the 1084 monitor is one of the main reasons for blowing Amiga's since this is only uses live and neutral and is not grounded.
And when you connect the RGB connector to your Amiga while the monitor is on you can probably see little sparks when it touches the video connector on the Amiga.

Grounding the whole unit this way is the safest for your computer.  But you've gotta be 100% sure you are safe yourself. Even having an AC plug with an earth only (to ground your unit for maintenance) has a certain level of risk

[Buzzfuzz]

Grounding the whole unit this way is the safest for your computer. But you've gotta be 100% sure you are safe yourself. Even having an AC plug with an earth only (to ground your unit for maintenance) has a certain level of risk

I'm a certified engineer in replacing electric meters and gas meters, I'm used to working with live wires that supply 3 x 400 volt and between neutural 3 x 230 volts, so I know a bit about voltage and currents and static electricity
Have had my share of shockings.