Someone uploaded #Derctuo to a place called Dokumen.pub, which says it’s by a guy named Michael Browner in Montreal but for some reason has its UI in Polish, German, and broken English.
this somewhat sketchy site claims to compress #PDF files. Dokumen.pub links there, so I wonder if it also adds them to Dokumen.pub.
#News from 02002 about "necklacing" making a return to #South-Africa. “In scenes reminiscent of the highly controversial necklace attacks by anti-apartheid youths on collaborators with the apartheid regime in the 1980s, the three men had tyres placed around their necks and were then doused with petrol before being set alight.” After a trial in an informal justice system, though.
metal oxide semiconductor (#MOX) gas #sensors #electronics #hardware #tutorial
02025 #paper “A Review: Applications of #MOX #Sensors from Air Quality Monitoring to Biomedical Diagnosis and Agro-Food Quality Control” #CC BY kind of #vapid in a way that suggests AI slop
#Witchcraft-and-Alchemy #video about #bootstrapping thinner aluminum #foil material for a ribbon microphone, noting that the usual stuff is about 10μm, testing with a micrometer, while ribbon-microphone #sensors are ideally 1.5–3μm. He reduces the thickness of household foil by etching the foil with NaOH #materials, 4g dissolved in 200mℓ of water (½ molar, he says), which evidently thins the foil fairly evenly. He glued foil to some plastic roundrects to hold it in place during the process. There’s a point where the foil becomes a very fine mesh, some time before being ripped apart by the hydrogen bubbles after about half an hour. He did a 4-liter test to try to hold temperature more constant. I suspect you could get smoother dissolution with the proper regime of #electrolysis, reducing asperities, but he didn’t try that. For thickness measurement, he did the same repeated-folding-in-half thing that I did, but with a micrometer instead of calipers or a ruler to measure the result. He says some of the foil had “the structural integrity of a wet paper towel,” making the process more difficult. The thinnest acts like gold leaf, sticking to his tweezers. The data shows a linear decline in thickness from 10μm at 5 minutes to 0 at 40 minutes, with a 35-minute sample being 2.2μm thick.
So he made some more samples; he tried to etch them for 32 minutes (before a citric-acid stop bath and water rinse) but they fell apart at 25 minutes.
In order to compensate for unknown temperature and agitation variations, he decided to measure the foil’s resistance during the etch process with a constant current. For #metrology, he amplifies the voltage drop across the foil with a differential-to-single-ended converter based on a LM833 dual op-amp #electronics, with an LM317 set up as a 100mA constant-current source, and a couple of relays set up to reverse the current direction through the foil to eliminate any offset errors, including from any unintended galvanic cells. Also he used an angle grinder to cut some blank PCB into a four-wire Kelvin probe so he’s only measuring the resistance of the foil itself, not the resistance of the copper leading down to the foil. The copper is painted black, presumably to protect it from the NaOH. And he’s using something like a Black Pill to record the data.
The 10μm foil is about 70mΩ (=7mV) at first, decreasing roughly linearly with less than 10nm of noise, enabling thinning the foil down to under a micron before it broke.
If you were doing this electrolytically, you could presumably stop the etch directly from the microcontroller with a transistor or even directly from a GPIO.
Then he repeats the etching with a large sample in the same bath with the thin foil strip whose resistance he’s measuring. And then he corrugates his foil ribbon microphone ribbons before etching them to thin them, which answers a burning question I had, and then he recorded the video with the resulting microphone!
An amusing editing trick is that he recorded himself erasing a whiteboard drawing line by line with his finger, then played the video backwards with a voiceover to make it look like he’s drawing with his finger.
Amazing #embroidery #video doing kintsugi on a hole. #fiber-arts
#Video from last year by #Stealth-camping celebrity #Steve-Wallis in a plywood “fort” designed to blend in under a bridge in Yarmouth, Nova Scotia.
He took some peeling paint from the bridge to a paint store to match the bridge’s paint color, then painted the plywood with a roller in his garage. The plywood was stiffened with other boards. He installed a TV and a self-inflating air mattress. He deploys a Starlink antenna off the side of the bridge for Internet access. Some vertical plywood boards, painted gray to look like the nearby concrete (taking a concrete chip to the paint store for a match), form “ground skirting” around what I’ll call his “access shaft” from the bridge loft down to the ground, where he has also set up a camping chair, since up on top of the painted plywood loft, the roof is too low to sit up. The entrance to the “access shaft” is somewhat hidden behind bushes.
He has a propane heater and some camping propane cylinders to warm the space up (it’s 5°, with -2° expected at night — frost formed), which he warns can stimulate spider egg sacs to hatch and create an explosion of baby spiders. He also has a big fluffy sleeping bag, a coat, and jeans with a warm inside liner.
It’s pretty noisy.
His Lander-brand LED light can be dimmed from his cellphone (Bluetooth?) and is also a power bank. He struggles a bit with lightproofing the seams where the plywood panels meet the ground, one another, and the bottom of the bridge. He hangs some camo netting in the doorway to the “access shaft” to reduce the amount of cold air coming in, which presumably also helps with the light.
He cooks a meal in a skillet on a one-burner propane camping stove from ingredients brought in cans and a ziploc: chicken breast, artichoke hearts, cherry tomatoes, garlic, sauteed in olive oil with pepper and white wine, Campbell’s prediluted broth, parmesan, and finally some fusilli pasta.
Then he engages in nostalgia about his dead “crazy neighbor” Glen.
To remove the “fort”, he and a friend come back the next night wearing high-visibility vests.
27' #Applied-Science #video about copper atomic layer deposition #manufacturing #toread
#video of a stone sphere made from “yooperlite”, a granite (or actually syenite, since it contains almost no quartz) with some spectacular sodalite fluorescent crystals (under 365nm UV) included in it, using automatic rock-sphere grinding #mechanisms. #formina
#Video of long-running electrical #mechanisms (EZ-Spin motors, etc.)
#Video on different ways to use fire in the shop, such as flame cutting steel, bending steel tools, unbending bent-up pieces of steel, expanding frozen nuts, heat-treating steel, welding, fire-finishing wood with a weed burner, starting a fire in the fireplace, lighting a coke forge, etc. Annoying #clickbait title. Reasonable #manufacturing beginner #tutorial.
#Bigclive #electronics #video on an old sound-detecting dusk switch, which turns on a light when you speak near it, but only after dark. In order to be able to switch AC current with a low trigger current, it uses a unidirectional SCR thyristor across a bridge rectifier, which can be triggered with 200μA. He says it’s old, but the main diode is an A7, the microcontroller looks like a SOT23-6, and everything is SMD. But it probably predates RoHS because it has a CdS photoresistor. There’s a 6.2MΩ SMD resistor involved (“625” label on maybe an 0603) which I don’t think I’ve seen before; at first Clive thinks it’s a collector resistor, used to get a high gain out of a grounded-emitter microphone amplifier, but later he thinks it’s being used to supply almost a microamp to the transistor base to just barely bias it into conduction, which would mean that the collector resistor was just the MCU’s internal GPIO pullup. The power supply for the microcontroller is even simpler than a cap dropper: D -- 100kΩ -- (~Z(5.1V) || 100μF || 0.1μF), with a half-wave rectifying diode and only a 100kΩ resistor to limit the bias current for the 5.1V zener, so the peak current is probably (339V - .7V - 5.1V)/100kΩ ≈ 3mA. Which is a very toasty 1 watt peak on the largish (1206? which is ¼W) series resistor, but that’s only some of the time; the RMS voltage across the resistor is only half of that, which would indeed give a quarter watt.
Another #Steve-Mould #video about #Gelsight #microscopy, which uses raking light from many angles inside a transparent gel pad to scan the surface topography of small objects in 3-D.
#video on spinning top #mechanisms: it turns out that by spinning an off-center weight inside the top you can get it to keep spinning.
#Steve-Mould #video #toread on optimizing spinning Euler discs
#Strandbeest #video with #music by Jos van Hout from a few months ago
#Video #toread on triggering xenon flashbulbs with #electronics
list of high-phosphate foods for people with chronic kidney disease (CKD). #nutrition
solenoid inductance #calculator
#OpenClaw found a #security hole on this Pilates gym’s website, so it used it to book its owner a spot. I’d say “containment escape” but OpenClaw doesn’t even attempt containment. #AI
#Holograms made with a pen plotter following Bill Beaty’s approach.
#Steve-Mould #video on hand-drawn #holograms #toread
LCD voltage test screwdriver #hardware
#Video of comedian Desmond Bishop/Bi Hansheng about how he mispronounced his #Chinese name at first
in #USA #history this was the moment in 01961 when drug companies had to provide evidence of efficacy to sell their drugs
Science #fiction #video made with AI about “The Day the Pillars Fell”.