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One of my first jobs 30+ years ago was ESD testing automotive and consumer electronics. I would spend a week with a discharge gun methodically running different
by yborg 3y ago
One of my first jobs 30+ years ago was ESD testing automotive and consumer electronics. I would spend a week with a discharge gun methodically running different discharge energies and waveforms both directly onto the devices as well as onto radiators at various distances from the device under test, as well as any cabling/harnessing that attached to the device.
Then the design team would figure out the reason for any resets or operational anomalies (or damaged components) and put whatever additional suppression was needed. Sometimes this required rerouting of traces to reduce coupling or redesign of the ground plane. It's a tricky business and expensive if you want to do it right. I suspect that your average $120 display does not see this kind of testing.
- mlyle 3y agoCars are a terrible ESD and EMC environment and safety critical at the same time. Computer equipment usually does pretty well, especially after installation (when there's good ground path everywhere and it's in a chassis). Between ferrite beads and TVS, there's a pretty good amount of protection, and I've seen pretty few ESD anomalies-- a reset or two when touching connectors long ago is about the extent of it. RFI and EMC is another matter. When I was operating a 100W 30MHz transmitter indoors briefly, the computers around did all kinds of wacky stuff. Flashing screens, random mouse clicks (from wired mice), transmitting packetstorms on their own, etc.
- Eduard 3y ago> When I was operating a 100W 30MHz transmitter indoors ... Ehm, can it still be considered "indoors" if it's 100W at 30MHz?
- systems_glitch 3y agoThat was my experience with the first spark gap switched Tesla coil I built. Running it in the basement would make stuff freak out on the upper floor.
- addled 3y agoAs a kid, someone gave me a toy keyboard. Checking Google, it looks nearly identical to a Casio PT-1, but was probably a clone or slightly different model. 9 year-old me was delighted to discover that it would start playing on its own when it was near the plasma globe I had bought at a science museum gift shop. I couldn't explain it, but eventually came to a vague understanding. It was semi-random, mashing together short, distorted sequences from the song bank stored in memory. Being almost recognizable made it more haunting. I remember bringing this out one night during a sleepover and we all got kind of spooked. Fun times!
- abakker 3y agoI am pretty sure I had the same keyboard and plasma globe!!!! IIRC, you could also get the keyboard to play when you set it on top of the SCSI external CDROM drive that came with my mac 2400c.
- quijoteuniv 3y agoI had that keyboard and we sat listening to the spooky random music once, i did not know you could reproduce it with a lava lamp! I loved it it was even playing notes out of the register so low that the speaker could not reproduce. Pure magic
- tinglymintyfrsh 3y agoMy dad's car had velour interior. Anytime the humidity was below 50%, expect the car to zap you and to be zapped touching door handles. I assume there are/were numerous gas station fuel fires from cars with velour upholstery.
- eitland 3y agoOne stupid little thing I realized after having sometimes been consistently zapped by mybcar door and other times not getting zapped in the same weather and humidity: If I open the door and grasp for the (metal) edge of it before I start sliding out of my seat I will be grounded and consequently not build up charge as I leave the seat.
- moron4hire 3y agoOne of the worst shocks I've received in my life was not accidentally touching one of the prongs of a half-inserted 120v mains plug, but pulling one of my fleece blankets off of the other on my bed, and then getting my shoed foot within 6 inches of my metal bed frame. I almost fell over, grabbed the upper part of the frame with my hand, and received yet another painful shock.
- mrexroad 3y agoI’ve had more than my fair share of 120v shocks, but the worst shock(s), by far, happened when blowing cellulose insulation into my attic. The 75’ (100’?) hose was a little unwieldy and I wanted more control in filling areas near eaves (small attic, lots of crawling), so I taped a 3’ section of 2” pvc pipe to the end of the hose. Holy hell… continuously, the static would build for a few minutes until it’d discharge through my gloves. First time it happened I pulled my glove off thinking it left a burn. There wasn’t really much I could do the discharge the static when I wasn’t near a vent or flue.
- iforgotpassword 3y agoWe had some carpet at my old workplace that would always charge you up and get you zapped. Whenever you touched anything metal. So the old and wise folks there immediately told you to grab your key when you get up and then use it to touch something metal, so the spark is between your key and the metal object and you don't feel anything.
- varjag 3y agoA 100W transmitter is a crapload of energy, way beyond most consumer and industrial EM immunity requirements.
- mlyle 3y agoYup, though I was also nowhere close. It may have been conducted EMI.
- Eduard 3y agoTVS == Transient-voltage-suppression diode? https://en.m.wikipedia.org/wiki/Transient-voltage-suppression_diode https://en.m.wikipedia.org/wiki/Transient-voltage-suppressio...
- mlyle 3y agoYup, explicit TVS or just diodes doing clamping or whatever. There's a fair bit of protection circuitry around. Often there's series resistors which help a lot, too. Not to mention that all modern CMOS chips have protection structures on the input (though not really as good as you'd like for something that is randomly handled by charged up humans).
- VectorLock 3y agoOld school sensitive CMOS chips pretty much made the market for "wrist strap" ESD.
- ansible 3y ago> Cars are a terrible ESD and EMC environment and safety critical at the same time. Had a bad incident a few years ago where EMI created by the windshield wiper motors on a large vehicle was causing voltage dips and spikes for our product. We had protection circuitry so that if the incoming voltage was too low, it would shut down our system cleanly.
- mrguyorama 3y agoSaitek (now logitech) sells flight simulator peripherals in the form of a throttle box and separate flight stick. They use two different USB cables and plugs instead of connecting one to the other, and they are technically two different devices. If you connect them to the same USB hub or to a USB system with not enough power, they will seem to work just fine, but will send a completely random button press or stick movement every so often. Changing ports will fix this. Another logitech one: I have a g27 steering wheel/pedal set/shifter combo. The pedals plug into the wheel, which also connects to a power supply and USB cable to connect to the computer. If you plug the steering wheel into the power and DON'T plug in the USB cable, metal parts of the pedals "leak" current, and you can feel a painful sensation if you touch the metal with exposed skin.
- m463 3y agoReminds me of woz's apple video on ESD: https://youtu.be/hLOQ7zOWGAA https://youtu.be/hLOQ7zOWGAA Personally I remember having a pickup truck with a velour seat. During winter I would slide off the seat at a gas station and the first thing I would tough would be the gas pump handle - ZAAAP. Not what you want at a gas station!
- eastbound 3y agoThat’s why in Europe the gas nozzle doesn’t have the little lock - It requires that you keep pressing it. So that you avoid going back to the car, charging static, coming back to the nozzle and having a spark.
- rft 3y agoThis is not the case for all of Europe. At least here in Germany our gas nozzles have a lock, no need to hold it.
- Gare 3y agoI've never seen nozzle without a lock in Europe (Croatia and countries close to it).
- spacemanspiff01 3y agoParts of US have this, (where it snows and is dry enough in the winter to be an issue.)
- is_true 3y agoIt's really mind blowing learning the reason behind some design "flaws", which clearly aren't flaws
- shard 3y agoThis reminds me of the 1st electronics company I worked at. We didn't have any ESD equipment, so I built a circuit which took power from a wall socket and pumped the voltage up to 2kV using diodes and caps, and sent that through a simple human body mode resistor/cap (https://en.wikipedia.org/wiki/Human-body_model https://en.wikipedia.org/wiki/Human-body_model) to do ESD testing. It worked well enough for the simple testing that we did, and was successful at finding weaknesses of our PCB layout for static protection.
- wlesieutre 3y agoExpensive screens screw it up sometimes too. LG had a $1300 5K Thunderbolt display that didn't work within 5 feet or so of a wifi router.