EEVblog #768 - Cordless Anti-Static Wristbands BUSTED!

[apis]

Anyone who works with ESD sensitive stuff would realise this won't work so I'm wondering who's buying these? 

Anyway, nice demonstration!

[foxx_hun]

Why did they even bother putting the 1 meg resistor in the wristband?  Did someone at the chinese "factory" actually believe in this? I can not understand the philosophy that underlies in chinese "products".


(I'm new at the forum, watching Dave's videos for ages )

[PA0PBZ]

Never stood on an IC, can't imagine it being worse than standing on lego though.

14 little razor blades > 6 blunt plastic bumps.

Don't underestimate the pain of standing on lego.

At least the lego detaches when you lift your foot, you have to remove the dip yourself -> double pleasure.

[linux-works]

I've reported these sellers to amazon so many time, but they do nothing.  some idiot kept trying to argue with me and it got funnier and funnier (well, sad, really).

ah, the corona effect.  yeah, that's it.

(sigh).

it does speak poorly of amazon when they allow BS like this to be sold.

ebay: that is the wild wild west and I gave up trying to care about ebay; but amazon does have real customer service folks who seem to care.

but even if I link to this thread, the amazon guys will NOT stop sales of this crap.

morale: sellers who give a cut to a business get to make the rules; the buyers are not really part of the formula.  "don't cancel his account; he sells stuff and we make profit from it!"

sigh ;(

[zapta]

Remember, there is no such thing as absolute potential, so in the absence of a dominant reference point like a planet, all you need to do is equalise charge with the other craft in a non-destructive manner.

Which brings the question, isn't sufficient to equalize to workbench level rather than to Earth's ground?

[TheAmmoniacal]

i think you are reading too much in this products advertisement.

it is exactly what it states : a cordless antitstatic wristband. 

it comes without a cord. you need to provide your own ... just list the little screw, slip your cord under it and tighten the screw. the 1 meg resistor is in the case.

The eBay ads do say:

Static dissipative strap without grounding cord, convenient to operate.
Avoid the trouble of ground cord and reduce the damage of electric components accidently.

[Ian.M]

If *everything* that can come in contact with the static sensitive devices is at the same potential, then yes, you could equalize to workbench level.  However workbenches totally free of mains powered tools and test equipment are extremely rare and if the board under test was touched by any grounded probe or tool the whole bench would discharge through the board.  Even if the tool was isolated, if mains powered, its typical capacitance to earth or neutral is usually high enough that a large ESD discharge would occur, charging up the capacitance.

Occasionally it is expedient to work on equipment using equipotential ESD precautions.  e.g. a simple wrist strap connected to an otherwise isolated PC chassis is adequate for working on it as long as you don't place or pick up any parts other than from within the chassis or conductive surfaces directly connected to it (e.g. the top of the PSU or CD drive) once you have removed them from their antistatic containers, which must be held in your hand while removing the parts.

[Franz Zinn]

Aircrafts use sharp pointed object to dissipate static discharge into the air. I would guess they do so by building an electrical field high enough to cause breakdown into air, which dissipates the charge. I wonder if it is even possible to construct such a devise for the voltages developed in a lab.

On a different note I will be grateful if anyone could suggest how one may measure static charge in a hobbyist lab with typically available equipment, without a surface voltmeter.

[SeanB]

Aircraft typically have static discharge points on the wings and trailing edges of the airframe, where you have some carbon fibre bundles and sharp stainless steel wires attached to the frame with a very good electrical connection, so that the arc discharge from lightning strikes will vapourise this point in preference to other more vital points.

Space craft simply use discharge points outside the metal frame, so as to reduce the build up of charge. Internal systems are inside a Faraday cage made from the outer shell, you simply make sure all metal parts like antennas and solar panel mounting parts have a DC connection that can handle high current flows as they get charged from either protons or electrons floating in space, and the discharge points are there to more or less equalise the charge distribution around the craft.

If you have a long tether or arm, and place a discharge point on the end, and charge it to a high negative voltage, with the main body also having equalising discharge points, you can get a thrust from the electrons emitted from the high voltage corona, which has been used for station keeping on some craft. If you want higher thrust you use Xenon gas, and charge it positively and use an ion gun to fire it out, along with an electron gun co linear to neutralise the craft charge.

[rs20]

I'm not sure if such a thing is possible or not. I can imagine a battery powered device that generates opposite charge to the one at your wrist in order to cancel it out. I don't know how you'd go about making it, but I can imagine it.

(Wrist-mounted Van-Der-Graaf generator?)

Easy to test. Silk cloth, glass rod and a battery.
Rub glass rod with cloth and it should attract small pieces of paper, touch rod to negative terminal on battery glass rod should now be chargeless. My bet is it will still be charged

A van de Graff generator is a bit more complex than a battery...

[EEVblog]

i think you are reading too much in this products advertisement.
it is exactly what it states : a cordless antitstatic wristband. 
it comes without a cord. you need to provide your own ... just list the little screw, slip your cord under it and tighten the screw. the 1 meg resistor is in the case.

Nope, read the ad.
http://www.ebay.com.au/itm/Anti-Static-Wrist-Band-Strap-Discharge-Cord-Cordless-ESD-Ground-Grounding-/151363238201

This Advance type cordless wrist-band enables you to work without the restriction of a gorund lead

Put this unit on your wrist at least 5 minutes before working on your various electronic parts

[Ian.M]

They might as well add a magnet to it as well so it can cure seasickness and arthritis!

There's already an extreme odour of ophidian short chain lipids, and that would open up more gullible markets. 

[BobC]

They might as well add a magnet to it as well so it can cure seasickness and arthritis!

There's already an extreme odour of ophidian short chain lipids, and that would open up more gullible markets. 

I was just scrolling to the end to add this, and you beat me to it!

Everyone knows that static electricity on the body is caused by an imbalance in the Chi (Life Force) caused by all the artificial things in our environment.

It is equally well known that wearing magnets helps restore the Natural Chi Balance.

What's a real tragedy here is that wearing a "normal" anti-static strap drains the imbalance to ground, which makes your internal Chi balance WORSE, since it forces the imbalance to be purely internal, with no external manifestations.  Who would want to lose Chi by using a normal anti-static strap?

So adding a magnet to this device will not only take care of static electricity at the cause (rather than draining your Chi away to ground), but will also provide the multitude of other curative health benefits of magnets.

So, yes, the device is defective.  But adding a magnet would certainly fix it.

;^)

[John Coloccia]

Nope, read the ad.
http://www.ebay.com.au/itm/Anti-Static-Wrist-Band-Strap-Discharge-Cord-Cordless-ESD-Ground-Grounding-/151363238201

This Advance type cordless wrist-band enables you to work without the restriction of a gorund lead

Put this unit on your wrist at least 5 minutes before working on your various electronic parts

 

I take it back...what a pile of crap.  I'll bet money that this thing has some legitimate use, and he just had the bright idea to buy a bunch and sell them like this.  Unbelievable.

But I notice only 2 have sold so far.  There's yours.  I wonder who the other guy is.

[sleemanj]

But I notice only 2 have sold so far.  There's yours.  I wonder who the other guy is.

There's about a bajillion sellers of these.



218 happy customers 

[ThunderSqueak]

Dave debunks cordless anti-static wristbands you can buy on ebay for $1. Do they do anything at all?
Controlled quantitative static voltage measurements with a surface DC voltmeter are done to prove they are 100% bullshit!
And a direct comparison with a proper anti-static wrist strap and bonding point is included.

This episode really brought back memories!

I worked at an IT shop about 15 years ago and we were doing PC repair, it was a very large corporation.  One day my boss came in and gave everyone one of those  wireless straps and said "I expect you all to wear them, it is the new company policy"  I was extremely skeptical and did some testing.  It took about 1 minute to prove that they were complete bullshit   Even so we would get written up if we were not wearing them, even if you were wearing a corded one instead.   Gotta love corporate policies

Magic!

~ThunderSqueak

[bitwelder]

I wonder if in Chinese 'cordless' has a different meaning: 



(added bonus: a safety-related device by... YOLO, what more can you ask)

Aircraft typically have static discharge points on the wings and trailing edges of the airframe

Idea: replace antistatic wristbands with trendy emo/punk bracelets 

[Aaron Stein]

Not 5 minutes ago I noticed this piece of crap being used in a DEEPCOOL factory.
There's the link: https://youtu.be/VcUoHDtsD4Q?t=1m15s

[amyk]

Not 5 minutes ago I noticed this piece of crap being used in a DEEPCOOL factory.
There's the link: https://youtu.be/VcUoHDtsD4Q?t=1m15s

It's not as if fans are particularly ESD sensitive... but now I'm more tempted to say that this isn't just "lost in translation" but rather scammy, if the Chinese themselves are falling for it.

[station240]

Nope, read the ad.
http://www.ebay.com.au/itm/Anti-Static-Wrist-Band-Strap-Discharge-Cord-Cordless-ESD-Ground-Grounding-/151363238201

Some NSFW items in that sellers negative feedback, who the hell sells cheap and nasty "personal" items ?
A fake item that does nothing is just the tip of the iceberg for at least some of these sellers.

[DanielS]

Aircrafts use sharp pointed object to dissipate static discharge into the air. I would guess they do so by building an electrical field high enough to cause breakdown into air, which dissipates the charge.

The difference here is that planes have huge metallic surface area with massive airflow building up charge on the skin and no discharge path for it to leak out through grounding, so the airplane would charge to tens of kV if there weren't those sharp points providing a sharp voltage gradient to ionize air and safely dump charge back into the air stream. There still needs to be 2-3kV of voltage difference between the plane body and surrounding air for this to work though, since there is not going to be much ionization going on below that.

Wearing a strap with sharp needles poking out of it to discharge static to air would be effective at preventing you from building up more than about 3kV worth of potential, which is completely useless for working with electronics. And as Dave has shown, building up more than 2kV under typical lab conditions actually requires some effort, so you are unlikely to run into many situations where a spiky strap would be of any use.

[spackard]

Not 5 minutes ago I noticed this piece of crap being used in a DEEPCOOL factory.
There's the link: https://youtu.be/VcUoHDtsD4Q?t=1m15s

 

You have to use these things with the bluetooth-less antistatic wrist strap base station.  For only $99.95.

[poot36]

Well i think my socks are cotton and carpet is just standard stuff you would find in a house.  The humidity is usually around 60% to 80% if my humidistat is correct and the temperature is around 20C.  As far as I know I have not damaged any electronics using this setup (I work on the carpet).  I have even run desktop and laptop motherboards on the carpet and had no problems.

[lapm]

Not 5 minutes ago I noticed this piece of crap being used in a DEEPCOOL factory.
There's the link: https://youtu.be/VcUoHDtsD4Q?t=1m15s

Well at least some of those workers had proper wired grounding straps..

[amyk]

Nope, read the ad.
http://www.ebay.com.au/itm/Anti-Static-Wrist-Band-Strap-Discharge-Cord-Cordless-ESD-Ground-Grounding-/151363238201

Some NSFW items in that sellers negative feedback, who the hell sells cheap and nasty "personal" items ?
A fake item that does nothing is just the tip of the iceberg for at least some of these sellers.

Huge item diversity is normally because these sellers are dropshippers that just aggregate listings from tons of others and add their own markup.