Does anyone know of a spray or something to stop static. We have a swivel chair, one of those well padded Executive sort in fake leather, probably pvc of some kind, and it seems whatever clothing I wear, when I've been sitting in it a while and get up the first large chunk of metal I touch gives me a shock,a and its so loud people can hear it across the room it even goes through painted surfaces. The other thing which is causing it is a cushion which seems to be filled by a kind of fibrous material often used in Duvets, which also crackle as you take the covers off of course so must be prone. Now I know all about negative and positive ions and how the imbalance causes a charge etc, but short of soaking everything in slightly saline water, I really do need to try to cut it down. I myself don't care, but some of the more delicate people swear its faulty wiring or something which it is not. Brian
The recent run of very dry weather has led to much lower levels of humidity which would assist static build-up. You could try a humidifier to see if that helps.
I once had this problem with a car. Get out, close the door, and get nasty shock. I found two answers. (1) close the door using the window glass and (2) hold on to metal frame of door before putting foot to ground. This latter may be of use to you
My old Sierra went though a phase of high levels of static buildup and in that case it was down to the tyre compound (low carbon content)?
I used one of those semi conductive rubber straps bolted to the towbar frame that used to 'fly' off the ground once moving (so didn't wear out or make a noise) but would touch the ground (and so earthing the car) when stopped. I think some people used light chain.
It did eventually wear short so might then only touch if you had some extra weight onboard but it worked very well till then (and I would certainly know when I had stopped with it clear of the ground).
I think that in ESD sensitive environments if they don't want the restrictions of wrist bands I think I have seen a form of dangling ankle strap on a semi-conductive mat ... that keeps the charge levels low but allows freedom of movement.
I wonder if brian put some silver foil on his chair then joined that to some dangling plug chain that touches the floor via a 10k resistor (or whatever resistance is normal on such things)?
In the days of old televisions, anti-static furniture polish used to be available.
If you don't mind sliding off your fake-executive chair, Mr Sheen apparently is anti-static and shifts shields and shines in sheconds, or CPC have Ambersil anti-static spray, part number SA02315
(reposted via Solani) The recent run of very dry weather has led to much lower levels of humidity which would assist static build-up. You could try a humidifier to see if that helps.
There's a different product for treating carpeting. (I hate products you keep having to apply over and over and over again.)
If you're making homemade ESD straps, the dissipation resistor you want is in the 1 megohm to 22 megohm range. The 1 megohm one is easier to verify occasionally with your multimeter, that it's still working. The purpose of the resistance value, is to reduce the "peak current" discharged into any semiconductor junctions. The 22 megohm value is the highest resistance value commonly available at retail.
Aren't there testing stations they use for checking the viability of ESD gear in such environments?
Sure.
The purpose of the resistance <g> is to allow a slower dissipation of the charge energy to minimise high current shock loads AND to ensure the operator isn't connected to ground with a low resistance path to increase the risk of electrocution from some live equipment.
I know it can be surprisingly high (in normal electronic circuit terms) because all it needs to do in most cases is 'leak charge' away from the user, or any charge differential between isolated components in a safe way.
There was an ESD module in the Novell 'Service and Support' (5 day) course I used to present when I was a CNI and I used to continually monitor their use of ESD gear after that module and throughout the rest of the course.
Roughy ever other week for about 7 years I had 8 delegates strip a PC down (they worked in pairs) and that included removing the CPU and RAM from the MOBO and the MOBO from the case etc.
I was away for a week and they got a contractor in. The next week came in to present another S&S and found 2 of the 4 PC's were dead. (When you finish presenting your course you reset the room ready for whatever is going to be in there the next week [1]. If both instructors are present on the last day then you generally prepped your own).
I happened to see one of my previous delegates that I'd taken on another Netware module and he had been on the contractors S&S course the previous week. I asked if they had been presented with the ESD module, been issued the ESD kits or been asked to use them during the course and he said no. As it happened he was a reasonable tech, I had spare motherboards (as yet unneeded for 7 years) and he helped me get the two PC's working again with nearly no delay to the start of that weeks course.
Now, do I know it was poor ESD that killed the two boards? No, but it's funny they had been ok for all that time before ... ?
Cheers, T i m
[1] The admin staff would come round with a pack of CD's marked to match the PC's in the room and you would re-image all PC's from the CD's (it was quicker than pulling the images down from the server).
p.s. If I'm building a PC from scratch I will generally use an ESD wristband and strap and an ESD mat. If I'm doing general maintenance on my own gear I will often take a shortcut and just ensure there is no chance of any static charge differential between any components I am going to bring together (by having contact to both) and leaving the machine plugged in but not turned on at the wall.
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