Antistatic Desk Strip
I work at my desk on prototype electronic devices. To the left of my keyboard is an antistatic mat that usually contains embedded prototypes and other electronic devices. The antistatic mat protects those devices from static discharge when I touch the mat before handling the device. Sometimes, though, I will handle the device right at my desk while I’m doing embedded design work.
I don’t like to be tethered by an antistatic wrist strap. I would much rather put a big old mat over the surface of my desk. The trouble is – antistatic mats make poor desk surfaces.
So I decided that the best solution would be a static discharge strip right on the front edge of my desk surface. I couldn’t find anyone that made such a beast, so I made my own. And I did it for about two dollars.
Below is a picture of the front edge of my desk without a strip:
My desk surface is made from a six foot long counter top from a home center. It has a smooth writing surface.
The strip is made from a disposable wrist strap from Digikey that is about $1.50:
The antistatic wrist strap is meant to be used once and tossed. It has static conductive material running the length of the strip that is wrapped around your wrist and then the other end is attached to a grounded metallic surface.
If you unwrap the strap, the leading edge has the conductive strip of material that should be put in contact with your wrist skin. On either side of the conductive strip is adhesive material much like athletic tape. The strip continues “bare” for a little it – long enough to wrap around your wrist. Then the conductive strip is covered by the adhesive material forming the “cord” just like the cord of a regular wrist strap. At the far end of the strap is a bare and sticky sheet of copper to adhere to a grounded surface.
To use the strip, I want to get rid of the adhesive tape material. The strip pulls away easily:
But when you get partway down the length of this disposable wrist strap, the conductive material is cut in a zig-zag pattern. No doubt this is to make the strip longer electrically to increase resistance:
There is just no way to make use of this section of the strip. It just stretches out like the photo below:
Luckily this section is only near the wrist end of the disposable wrist strap. I just cut the strip off at this point and I only lose a bit over a foot of conductive material.
The adhesive tape is removed all the way to the end where the sticky copper connects to the conductive strip:
Once the adhesive tape is removed from the strip, there is nothing sticky about the strip. So on the edge of my desk I ran a length of double-sided cellophane tape. The double-sided tape is a little wider than the conductive strip:
The copper end of the strip is wrapped around the bare end of a wire that leads from the side of my desk to a ground point:
The strip is then run from one end of my desk about 30 inches to the middle. This puts the strip directly in front of me while I work. Since the double-sided tape is slightly wider than the conductive strip, I used an Exacto blade to cut off the excess tape:
The strip sets in front of my keyboard – a place that I touch frequently with my arms:
This has saved my bacon more than once. I know that shifting around in my chair I can conjure up a significant static charge. With the strip there I am constantly at ground potential.
Many years ago my mom “grounded me for life”. I’m just fulfilling that command. :-P
Please post any questions you may have.
Update:
LifeHacker (http://www.lifehacker.com) just pointed to this article. I appreciate the attention – I read Lifehacker every day. I want to clear up their text, though. “He had an antistatic mat, but it was on the small side, and expanding it to the size of his work surface was out of the question due to cost and space needs.” I’m not sure how that conclusion was drawn. I have mats to the side of my desk and I didn’t want the mat surface for my desk. Antistatic mats are a poor writing surface. And, Ladies, there is nothing small about my mat size. Wink. *cough* *snort*
On a serious note is the concern about resistance to ground. If you work on live circuits, you do NOT want to be well grounded. I wrote “The copper end of the strip is wrapped around the bare end of a wire that leads from the side of my desk to a ground point.” and in my setup my ground point is my static mat connection. If you implement this desk strip, you should consider adding a series 1 mega ohm resistor in the line (the wire) if you connect directly to an earth ground connection. Play it save – do NOT ground yourself when working with any circuit that is live.
Stay safe!
=Gizmo=
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[...] check out his full write up. Got an alternative neutralizing trick? Do tell in the comments. Antistatic Desk Strap [via [...]
This may be a silly question, but I am just beginning to fiddle with electronics and am slowly climbing the learning curve. I was wondering if the anti-static mat that you have acts as a ground or is it connected to ground?
I understand the idea behind voltage only being a potential DIFFERENCE and how you can virtually ground yourself by just being the same charge as what you are working on. I was wondering if the mat you use acts as an actual ground (connected to Earth in some way) or can simply contain and disperse enough charge within itself to work safely.
Oh, and I’m sure your mat size is more than adequate, because its not the size of the mat, but what you do on it ;).
The mat I have just to the side of my desk (and the ones I have in my lab) are all connected to ground. And the strip on the edge of my desk connects to the mat.
Not all grounds are the same. You can have two grounds in the same building that are at different potentials.
Yes, the idea is to not cause a potential difference across areas of the circuit.
My wife gave me a little static for my comment…
[...] Luckily, fellow shockaholic anonymous Rob Severson found a way to build grounding into his desk, which would automatically activate even before he’d touch his laptop/desktop keyboard. It involved peeling the conductive strip of a 3M anti-static strap, and securing it on the front edge of a desk with some double-sided tape. The copper end of the strip was then hooked up to a grounding wire neatly tucked away. Easy as pie, so long as you have the patience to carry it out. Full details here. [...]
This is the best thing ever. I don’t work on computers, but my office builds up incredible static, and I get huge zaps all the time. I followed your directions and have a strip on my desk now, and it’s made my enjoyment of work go up dramatically. Thank you!
I’m glad that I could help, Hannah!
[...] Luckily, fellow shockaholic anonymous Rob Severson found a way to build grounding into his desk, which would automatically activate even before he’d touch his laptop/desktop keyboard. It involved peeling the conductive strip of a 3M anti-static strap, and securing it on the front edge of a desk with some double-sided tape. The copper end of the strip was then hooked up to a grounding wire neatly tucked away. Easy as pie, so long as you have the patience to carry it out. Full details here. [...]
[...] check out his full write up. Got an alternative neutralizing trick? Do tell in the comments. Antistatic Desk Strap [via [...]