I can't tell you how many Made by Monkeys and Sherlock Ohms postings have involved static electricity. A lot. Static electricity has been the culprit in tons of design stories. Do you have any of your own stories that involve static charges?
I had my earphones plugged into a (grounded) audio distribution system mounted on the treadmills at the local gym (so we could select and hear television audio from various overhead monitors). I was electrically isolated, in intimate contact with a hard rubber belt, moving and rubbing against another surface. I felt a periodic sharp pain in my head while walking. As a static charge built up on me, the thousands of volts eventually had enough pressure to jump the gap between the grounded earphones and my ear canal. I didn't hear it beacuse the audio was louder, but I sure felt it. It took me a few moments to analyse what was going on. On my next visit, I grounded myself to the treadmill handrail using a standard ESD wrist strap/wire. Problem went away. No wonder noboby was listening to the TVs at the treadmill station. I told manangement and they bought a bag of wired wrist straps for their clients to use.
I never really thought of a treadmill as a Van der Graph generator but when you think of it, that is what it is: a horizontal Van der Graph genrator. I would have thought that manufacturers would of put some sort of grounder idler roller to drain the static charge incorporate some sort of conductive treatment on the belt. But marketing and cost reductions have probably overruled engineering. I'll be the PCBs in the treadmill probably has good shielding and grounding to reduce warranty costs.
"I've noticed at our local Walmart that as I push some of the carts, I get a static discharge through my hands. It's really uncomfortable. Have other's noticed this same problem?"
Often you will see some versions of shopping carts with a discharge strap or small chain hanging down rubbing the ground. This also seems to be a greater problem with the newer plastic carts than the older metal carts... There has been alot of info about this problem with a specific retailer which you can find by searching: Wal-martshopping cart static electricity shock.
That was most likely due to the static charge built up on the skin of your aircraft just from airflow. Rotary wing aircraft are particularly susceptible to this issue. Don't they always have you ground the skin before you put fuel in your plane? I'm not a pilot, but I have spent more than a few hours coming and going off of vaious flight lines, usually hauling a ruck.
Years ago I worked with a SW engineer who just couldn't (or wouldn't) take ESD seriously. One of his habits that drove me up the wall was he would put an IC on his plastic notebook and just slide the chip around in a circle on the notebook (a good way to zap the chip).
We could never get him to wear ESD straps. The final straw was when he walked into a lab I was working in. We had operational equipment set up on an ESD safe bench with the covers off. He walked over to one of my modules and touched an accessible board. I heard the zap from over 10' away. He destroyed the module. He also found new opportunities elsewhere not long after (probably unrelated to the ESD event).
It amazes me how so many people (many smart Engineers) just don't understand how little static electricity it takes to destroy electronics. Probably because often the induced failures are not catastrophic (the device will even appear to continue to work). Many of the real failures are manifest as weird or mysterious problems that cannot be pinned down. Because they don't see a ZAP and then a truly dead device, they assume they've done no real damage. I'll continue to be paranoid and minimize such problems.
Yeah 3drob... We get that too sometimes. I've been told by one EE that he's never zapped a board... 'Yet' is what I replied.
We have below 1% humidity in the dryrooms and an over active air exchange in one of those creates a bit of a breeze too. We do a good job of maintaining boot straps, wrist straps, ESD Lab coats as SOP in those... and we still get the occasional fire, so far though those always seem to be non-static events. Friction; go figure.
Dwight, you write very well – great article. Your descriptions of 'back then' vs today are hauntingly familiar to me as I was right there with you both times. The various companies I've served over the years learned the same lessons you've described, and ESD prevention has steadily gained prominence to become a standard initiative in the electronics industry. But because of that, I am very surprised the new camera you bought suffered a catastrophic failure from an ESD shock. It seemed to me that EVERYBODY was designing for prevention these days.
Unfortunately adequate ESD protection does not add to the "features" of a product, and it's lack will not be obvious until after the product is purchased and used a bit. And the very short warranty period has expired. So a bargain thing will usually have inadequate protection.
Of course, the story sounds like a really large charge was delivered, probably far beyond the typical one that a minimal system would be protected against.
Remarkable, I would have thought that with modern products and the amount of ESD testing that is supposed to be done that this would be a thing of the past. I've been involved in product development for the last 30 years and we zap thing repeatedly (30 times in development and then in compliance testing another 30) with 8kV positive and negative to all metal accessible parts and we don't even see a reset let alone damage. I wonder what went wrong here?
I read William K's reply and his point really suggests that as consumers we should only buy CE marked products which actually MUST go through this testing to be allowed to apply the logo. That way the shonky operators cease to sell products and we all benefit. The purpose of the CE mark was to lift product quality to a minimum standard deemed necessary for the application. In the EU it's enforced and placing a CE mark without complying results in fines and worse a need to remove the mark. Designing for ESD places some real challenges on the designer adding great skills and improving employment prospects (at least where it's mandatory :-) ).
Before you completely give up on the camera, try something:
Remove the batteries for a week or two and then replace them. The microcontroller may have jumped to a nonvalid program location. It may be jumping around in the program. Once the internal capacitor discharges, it will reset. I have had that happen with cameras and other comsumer products.
Good idea to pull the batteries. Didn't work, though. Not sure what the right way would be to discharge the alleged capacitor. I might try to remove the batteries and then short the DC + and - together. Otherwise, I'll have to take a look inside.
We had an ESD problem with Si wafer fork robot. Not only did the computer occasionally re-boot, but spark damage occurred on wafers withdrawn and/or inserted into their plastic cassettes. The solution: Isolate the fork and connect to ground through a giga Ohm resistor.
I once worked for a contract ICT test house developing test programs and fixtures. Our test head (HP3065) and debug bench was in a "static controled" room with a disapative carpet. One day durring the winter, I walked accros that rug, reached down into the empty patch bay of the test head and drew a 1" arc to one of the test card connections; it hurt like heck and I jumped back. I immediatley grabed the diagnostics fixture, and found that we had a dead analog card. It took two day of down time for HP to find the problem and get us a replacement card. So much for the anti static carpet. We got a lot more serious about wrist staps after we learned that we could not rely on the carpet any more.
I had a Medical instrument the was reported to reboot in a Swedish operating room that had very bad static charge issues. We could not duplicate the problem with a local unit, so the aquired the Swedish unit. I could not get it to fail with my sparky stick. The only clue was it happened when it was set for full volume. The volume control was for a anoying vacume level warbler sound. (so I always set it to minimun) I finnaly tried it at full volume. As it turns out the volume control pot set at maximum allowed a spark into the A/D which latched up the CPU, While a low volume setting sent the spark into ground.
Some decades ago we computerized the admissions department at a series of entertainment venues. The initial installations were in coastal Florida, where the humidity was high and we had no problems.
At a newer site in New Jersey the installation was in the cold weather and the terminals were resetting at random. We eventually figured out that the tellers' uniforms were rubbing up a static charge as they shifted on their stools, then the terminal would get zapped as they touched it to process the next patron. The fix was to install a conductive plastic cover over the seat cushion. We also removed the rubber tips from the stools' metal legs so that the stool would ground itself to the masonry floor.
In retrospect, attaching a length of sash chain to the bottom rung of the stool might have worked as well to ground the legs. But it might have created a tripping hazard.
Fifty-six-year-old Pasquale Russo has been doing metalwork for more than 30 years in a tiny southern Italy village. Many craftsmen like him brought with them fabrication skills when they came from the Old World to America.
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