4 ms·

Cars are a terrible ESD and EMC environment and safety critical at the same time. Computer equipment usually does pretty well, especially after installation (w

by mlyle 4y ago

Cars 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 4y 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 4y ago
That 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 4y ago
As 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 4y ago
  I 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 4y ago
  I 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 4y ago
My 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 4y ago
  One 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 4y ago
    One 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 4y ago
      I’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 4y ago
    We 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 4y ago
A 100W transmitter is a crapload of energy, way beyond most consumer and industrial EM immunity requirements.
- mlyle 4y ago
  Yup, though I was also nowhere close. It may have been conducted EMI.
Eduard 4y ago
TVS == Transient-voltage-suppression diode? https://en.m.wikipedia.org/wiki/Transient-voltage-suppression_diode https://en.m.wikipedia.org/wiki/Transient-voltage-suppressio...
- mlyle 4y ago
  Yup, 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 4y ago
    Old school sensitive CMOS chips pretty much made the market for "wrist strap" ESD.
ansible 4y 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 4y ago
Saitek (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.

by mlyle 4y ago

Eduard 4y 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 4y ago

That 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 4y ago

As 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 4y ago
I 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 4y ago
I 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 4y ago

My 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 4y ago
One 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 4y ago
  One 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 4y ago
    I’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 4y ago
  We 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 4y ago

A 100W transmitter is a crapload of energy, way beyond most consumer and industrial EM immunity requirements.

mlyle 4y ago
Yup, though I was also nowhere close. It may have been conducted EMI.

Eduard 4y ago

TVS == Transient-voltage-suppression diode? https://en.m.wikipedia.org/wiki/Transient-voltage-suppression_diode https://en.m.wikipedia.org/wiki/Transient-voltage-suppressio...

mlyle 4y ago
Yup, 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 4y ago
  Old school sensitive CMOS chips pretty much made the market for "wrist strap" ESD.

ansible 4y 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 4y ago

Saitek (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.