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knotimpressed commented on Miles from the ocean, there's diving beneath the streets of Budapest   cnn.com/2025/08/18/travel... · Posted by u/thm
ramses0 · 3 days ago
My first cavern dive was with a VERY experienced cave cartographer (Yucatan Cenotes, https://www.filoariannadive.com/alex.html ). Cavern is where technically "you can see the light", but if you turn a corner and can't see the surface then it converts into "cave" diving.

For the rank amateur that I was, being able to turn around, orient myself and see a sliver of light ~100ft behind me... yeah, "technically a cavern dive".

I tried to do a "buddy check" w/ him before beginning the dive and he almost pushed me away... the stories of him diving with side-by-side tanks, then pushing each of them through a gap in front of him, one by one, and then wriggling his body through. :insert-shocked-emoji:

Always remember: "Are you a diver, or a dummy?" ...what would a DIVER do? [don't panic, fall back to your training] Good to have that sense of self an security in lots of cases!

knotimpressed · 2 days ago
Why’d he push you away during the buddy check?
knotimpressed commented on Fire hazard of WHY2025 badge due to 18650 Li-Ion cells   wiki.why2025.org/Badge/Fi... · Posted by u/fjfaase
Cyan488 · 17 days ago
As an electronics designer myself, I would find it hard to trust the AliExpress board.

Without the design files, running a failure modes and effects analysis on the board is difficult.

There's also no guarantee that each board you get is built identically. Some parts or the whole design could be changed between orders.

If I was designing a power bank board professionally, I'd be putting it through the ringer - environmental, mechanical, component level short circuit, load short circuit, load power injection, input over-voltage, input transient, RFI/EMI susceptibility, etc. Do you trust that all that has been done on a board that is representative of what you've received?

knotimpressed · 16 days ago
Definitely agreed on the lack of consistency between orders and even between boards in the same order. I’m doing very low volume for myself and not giving anyone else the banks, so I’m more than happy to check over all the boards for visually obvious issues with a loupe.

As another commenter said, is there anything beyond short circuit/overcurrent for the load side, and undervoltage/overcurrent protection on the cell side that’s crucial for a non professional bank? I’m happy to pop a few boards testing them myself.

knotimpressed commented on Fire hazard of WHY2025 badge due to 18650 Li-Ion cells   wiki.why2025.org/Badge/Fi... · Posted by u/fjfaase
Eduard · 17 days ago
it helps if you give us links and model numbers
knotimpressed · 16 days ago
Well, there’s only one real part (the cells are interchangeable, and reclaimed) https://a.aliexpress.com/_mKNNnGZ I’ve gone with the purple C and U model.
knotimpressed commented on Fire hazard of WHY2025 badge due to 18650 Li-Ion cells   wiki.why2025.org/Badge/Fi... · Posted by u/fjfaase
ranger207 · 17 days ago
There is a subreddit dedicated to 18650s where people make power banks and the like, https://old.reddit.com/r/18650masterrace/ . Off the top of my head I remember reading about making sure you use the same set of cells together so you don't get unwanted current flow from highly-charged cell to low-charge cell, but I'm sure there's other details too
knotimpressed · 16 days ago
Absolutely, I’ve browsed that sub a bunch but frankly I trust the opinions here more. I’m using matched reclaimed cells that I’ve tested to make sure they’re still healthy.
knotimpressed commented on Fire hazard of WHY2025 badge due to 18650 Li-Ion cells   wiki.why2025.org/Badge/Fi... · Posted by u/fjfaase
knotimpressed · 17 days ago
Braving potentially getting spit roasted to ask:

If I'm making my own 18650 USB C power banks, are there any easy to miss risks? I've got the cells in holders, not welded, but the holders are specc'd above the current I need. The cells are unprotected, but the Aliexpress listing for the power management board says specifically to use unprotected cells, as at 6A draw most protection boards don't do well (dubious). The cells are tested and mechanically protected by a thick enclosure. The only EE work I'm doing is soldering 2 high gauge wires from the holder to the board that's doing everything else. I know Aliexpress isn't a bastion of quality, but the seller has good feedback and I checked over the board to make sure there's at the very least a good counterfeit battery protection IC included.

Currently, the concerns I have are: - the holder relies on good contact to deliver 6A without developing hotspots on the terminals - the board from Aliexpress perhaps should not be trusted

If there's anything else anyone can think of, I'm happy to hear it.

knotimpressed commented on Volvo delivers 5,000th electric semi   electrek.co/2025/06/29/vo... · Posted by u/JumpCrisscross
neom · 2 months ago
fwiw and not to diminish your point, semi trucks in Canada are rarely heard, they mostly drive along our massive highways, they are generally not allowed in cities, and you can drive from one end of Canada to the other (east <> west) on Highway 1 without entering cities/big towns, the most populated area you have to drive through is at the Ontario/Manitoba border. (Source, I've driven Canada fully, end to end e->w)
knotimpressed · 2 months ago
I mean, they’re rarely heard by people, but they’re certainly heard by everything else trying to live near the highway that as you said, cuts across the entire country.

Now, not to say you don’t make a good point, but noise pollution is pollution, and reducing it does have benefits.

I severely underestimated how loud a single semi was until I was camping 5km from a highway and couldn’t hear the cars, but could certainly hear the trucks.

knotimpressed commented on Backlash to artificial dye grows as Kraft ditches coloring for Kool-Aid, Jell-O   washingtonpost.com/busine... · Posted by u/bookofjoe
mrguyorama · 2 months ago
You should note, that Republicans only decided to go after artificial colors after the industry had already solved this "problem" for a hundred other countries.

Meanwhile, all this hubbub over "artificial" vs "natural" colors is fucking nonsensical. Very very few of the "artificial" colors have some evidence of maybe causing some harm from chronic exposure. Not that you should have chronic exposure to any of these foods in the first place since the sugar and fat and salt content alone is unhealthy and will cause you significant chronic health problems unless you exercise for a couple hours a day.

But it doesn't matter whether a chemical is produced by some process in nature or some process in a lab. What matters is how the human body reacts to it. Do we have tomes of evidence that eating "natural" colors is actually safe? No, we do not. Most of them are just GRAS (Generally recognized as safe, which is an outright misnomer) and therefore have no evidence of any safety other than "We used in the 50s so whatever".

Nevermind that "natural" food dyes aren't even! To make "natural red #4" involves taking large amounts of carminic acid from some bugs and reacting that with aluminum or calcium salts. In fact in the US, you can do pretty much whatever you want to a naturally sourced chemical and still call the product of that chemistry "natural".

Replacing well studied, simple, dyes with less studied dyes just because a core part of their chemistry was able to be sourced from """Nature""" is utterly stupid and pointless and meaningless. What actually matters is replacing ingredients that show some toxicity to chronic exposure with ingredients that have significant data to show they are not chronically toxic. There's no structural system in "natural" dyes to actually do that.

This push will not stop Dupont from extracting curcumin from turmeric, massively modifying it to make it easier for an industrial process to use without fouling up their equipment, accidentally make it cancerous after you eat it for 20 years, and poison us all with a "natural" chemical for decades.

"Natural" has no structural overlap with "Isn't unhealthy". Organic Ricin will kill you just as dead.

knotimpressed · 2 months ago
I despise the labeling around "Natural" and "Artificial" Colours|Flavours|etc. It's downright misleading to call one highly processed compound natural, while calling another equally processed compound artificial. I absolutely do not care what the feedstocks used were, I care about what the final product is.

On that note, I wish that food companies were forced to disclose which "flavours" they added to their products. Some of the artificial flavourings are the exact same compounds as natural ones (vanilla, cherry, and cinnamon are I'm pretty sure, they're just one isolated compound of many), and some of them absolutely are not. It would be really nice to know what I'm actually putting into my body, especially since so many flavourings are added to "natural" products like tea.

Does that kind of labeling exist in any country? I've never seen it on imported goods I don't think.

knotimpressed commented on Interferometer Device Sees Text from a Mile Away   physics.aps.org/articles/... · Posted by u/bookofjoe
knotimpressed · 3 months ago
I wonder if the requirement to rotate the target is inherent, or if it could be optimized away eventually?
knotimpressed commented on Strain gauge made out of PCB   github.com/vapetrov/PCB_s... · Posted by u/dr_coffee
knotimpressed · 3 months ago
For a long time I've been trying to make a DIY milligram-accurate scale, and milligram-accurate strain load cells are expensive. Does anyone know if the resolution of this is high enough?
knotimpressed commented on From: Steve Jobs. "Great idea, thank you."   blog.hayman.net/2025/05/0... · Posted by u/mattl
jrockway · 4 months ago
They must have learned from your experience. When we were acquired by HPE they did not let us choose and our director of engineering got an email address that misspelled his name... fixing it involved him being locked out of all systems while the people trying to fix it emailed someone else with a similar name about it. His advice for other team members in the same spot was "if you don't like your email address, do not attempt to fix it."

HPE was truly a trip. I paid $2000 to be able to disparage them online and it was worth every penny.

knotimpressed · 4 months ago
What were the details of paying $2000?

u/knotimpressed

KarmaCake day49April 2, 2024View Original