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Zapping Things With ESD Ė Just One More Service I Offer

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mhrackin
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Re: Maybe...
mhrackin   8/13/2014 3:45:57 PM
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I don't know what flavor notepad you are using, but I have a number of Lenovo Thinkpad power supplies on my desk right now, and i noticed that they have a TWO-WIRE UNGROUNDED (and unpolarized) AC plug.  I also have some ancient Dell ones with 3-wire cords.  Obviously, there's no point in ohming out the Thinkpad ones as there is NO input ground.  The Dells do have the ground continuous (1.2 ohms) to the shell of the DC power plug.  However, these are REALLY old (from XP PCs) so your results may differ.

Max The Magnificent
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Re: consumer versus industrial
Max The Magnificent   8/13/2014 2:41:38 PM
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@dt_hayden: If you grab the "ground" to make your connection, you could potentially make a direct discharge at that point.

Good point

Max The Magnificent
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Re: Notebook??
Max The Magnificent   8/13/2014 2:39:47 PM
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@Antedeluvian: I hope I am not alone in noticing that a notebook can run on batteries, in which case you have no ground at all.

True, but I never use it that way -- I always have it plugged in when I'm working on a hobby project.

dt_hayden
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CEO
consumer versus industrial
dt_hayden   8/13/2014 2:37:02 PM
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In general, grounding yourself through a piece of (consumer grade) electronic equipment for ESD control seems like a not so good idea.  You are making assumptions about the goodness of that ground and assuming the equipment can withstand discharges into that point.  If you are sure only the wriststrap connection touches the "ground" point, then currents are limited by the resistor in the strap anyway and less of a worry.  If you grab the "ground" to make your connection, you could potentially make a direct discharge at that point. 

Having said that, Tek scopes I have used in the past had a "grounded" banana jack on the front panel which I plugged into for ESD management.  My thinking was since it was industrial gear, Tek designs robust equipment, and the point was probably put there for that purpose, it was fine. 

If you are only dealing with isolated portable gear, I think it is more important to equalize potential to the gear, rather than to ground.  .I have clipped onto grounds of gear in these cases.  In this case, some (all?) soldering ground tips are grounded, so beware when soldering.

Max The Magnificent
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Re: Maybe...
Max The Magnificent   8/13/2014 2:34:55 PM
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@Crusty: I get over stretching the colied cable of the wristband by having a multiple socket strip...

Actually, that's not a bad idea -- I usually have a couple of these lying around -- but I'm going to check the USB thing first...

antedeluvian
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Notebook??
antedeluvian   8/13/2014 2:34:46 PM
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Max

I hope I am not alone in noticing that a notebook can run on batteries, in which case you have no ground at all.

Crusty1
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CEO
Re: Maybe...
Crusty1   8/13/2014 2:28:15 PM
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Hi Max : I get over stretching the colied cable of the wristband by having a multiple socket strip, on a lead from the wall socket, in England these are very cheap from Ikea. The soldering Iron and powers supply go into two of the free sockests leaving me with two other sockets for wristband and antistatic mat.

This approach any use?

Max The Magnificent
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Re: Maybe...
Max The Magnificent   8/13/2014 1:57:42 PM
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@Duane: In most US wall sockets, the screw that holds the outlet plate on is grounded. If that's the case, you could just connect to that screw for your earth ground.

But they I still have the probem that the wall socket is quite a way from the table -- unless I attach a loong piece of wire -- and I don;t fancy attaching and detaching that wire each time I want to play with my electronics...

Max The Magnificent
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Re: Maybe...
Max The Magnificent   8/13/2014 1:55:34 PM
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@Duane: Just to be sure, I ran it past a couple of my ESD experts here [...] if it's less than 1 ohm, you're good to go.

Potential Happy Dance -- I'll check thsi as soon as I get home this evening an report back in the morning...

Duane Benson
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Re: Maybe...
Duane Benson   8/13/2014 1:54:46 PM
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In most US wall sockets, the screw that holds the outlet plate on is grounded. If that's the case, you could just connect to that screw for your earth ground.

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