“An opportunistic lock (also called an oplock) is a lock placed by a client on a file residing on a server. In most cases, a client requests an opportunistic lock so it can cache data locally, thus reducing network traffic and improving apparent response time.”
has the published data from the Shelf Life Extension Program on 122 drugs from 02006, indicating which were still effective after their expiration date. Nothing mentioned about safety or toxicology.
#bigclive #video on the #electronics #hardware in an electric #flyswatter. The circuit is extremely simple! A transformer, a transistor (C2328A 30V 2A 1W), a 560Ω resistor, a diode, an 0.33μF 630V film storage capacitor, a 2.2MΩ bleeder resistor for it, and a probably unnecessary LED (with its own 560Ω resistor) and power button. It all runs off 3 volts from two AAs. It’s a blocking oscillator, basically a Joule Thief with a high-voltage secondary which is half-wave rectified into the storage cap; the resistor limits the current into the base of the transistor. Although I think I may have misunderstood how the Joule Thief works — he says the feedback winding turns the transistor on more until the core saturates, at which point it starts turning off. The two primary-side windings attached to the transistor are 1.5Ω each, and the high-voltage secondary is 150Ω. A commenter says his is 1500V, and he altered the output to 1μF 10MΩ for a “nice loud bang”.
older #bigclive #video on the #electronics #hardware in an electric #flyswatter, labeled as 1.5kV. It uses a (slightly weird) Cockcroft–Walton voltage multiplier on the transistor output, terminating in an 0.022μF kV cap with a 44MΩ bleeder, and has the primary side of the transformer on the (8050SS) transistor’s emitter (!) rather than its collector but otherwise a similar circuit to the later video.
another #video, by #randomtronic, of the #electronics #hardware in a 1.5kV #flyswatter. From a distance it looks like the same design as the contemporary bigclive video, but he has the transformer’s primary winding on its collector as you’d expect — but with a series resistor, which you wouldn’t. And only 7.2MΩ of bleeder resistance, and a slightly different voltage multiplier design, which he describes as “confusing as hell”. He is also skeptical of the transistor pinout he got from the datasheet, so he plugged it into his TransistorTester and found that the terminals were backwards. But the primary of the transformer is still on the transistor’s emitter, as in bigclive’s analysis, rather than its collector. His understanding of how the Joule Thief works is the same as mine and different from the explanation given by bigclive in the previous video, with the current switched by transistor turning it off rather than further on.
#randomtronic Joule Thief build recycling a common-mode choke. #hoarding #electronics #hardware #toread
#bushcraft stone house #video; not sure these adobe-mortared stone arches are really safe, especially since his adobe seems to have far too much expansive clay in it, judging by the cracks. What happens when it rains, and the wind wets one side of the building more than the other? Where did he get all those nice angular blocks of limestone of a consistent thickness? Why do I never see him use a plumb line? He uses a pair of supple saplings bent into an arch shape for his “centring” — but then never strikes it, instead plastering it with adobe. Then just in case he puts a big wood lintel over the top of the arch so it doesn’t have to bear any weight. #construction
#bushcraft stone house #video continued. He seems to have given up on arches at some point; the final window is sort of a corbelled arch, and the doorway appears to be unashamedly topped with a rather slender wood lintel. And the roof, rather than being any sort of arch or stone, is evidently corrugated sheet metal (or actually fiberboard composite?) laid over wooden poles, posing the question of why he doesn’t use glass in the windows. In this video he’s mostly adding adobe mortar and stone to chink up the gaps. #construction
#video on muscle-powered #mechanical cement-stabilized compressed soil brick #construction machine by Makiga Engineering Services of #Kenya, designed to make interlocking blocks that are stable even without mortar (though, I’d think, a bit fragile), at a rate of about one per minute with four workers. Costs 122 thousand shillings. The outside of the bricks do have beveled (chamfers) corners, but their interlocking features lack not just chamfers but even draft. #compressed-earth
#compressed-earth block #construction #video using #mechanical hydraulic cylinders to apply 1800 “pounds per square inch” (12MPa). Discusses screening (riddling?), mixing the soil with a farm-tractor-mounted rototiller, mixing in 10% portland cement, discovering you don’t have enough clay (he recommends 40% clay), making sure there’s no organics, etc. This machine (make, model, and pricing not specified) doesn’t seem to make chamfers or interlocking features.
#video on a #mechanical machine called “Blocco Mattone”, designed by Professor Roberto Mattone, RIP, which produces #compressed-earth blocks with a Lego #construction-set appearance, but for real #construction. Two rounded studs with a lot of draft (10mm tall, 38.7mm radius at top, 39.8mm radius at base) are on top of each brick, fitting into much deeper hollows in the bottom, and there’s a tongue at one end (15mm long, 40mm wide at tip, 56mm wide at base, due to the generous draft angle) and a corresponding groove at the other. There are no chamfers on the faces of the brick. The main rectangular body of the brick is 280mm × 140mm × 95mm. The stud centers are 71.5mm from the ends of the main rectangular body, and I don’t know how that’s supposed to work, since the studs in a course of bricks ought to be equidistant; maybe the hollows are larger to allow some slop. Organic material and gravel must be removed by “sieving” (riddling, I suppose; a window screen is shown being used). 6–12% portland cement. The brick press is muscle-powered; it uses a “floating mold” which can move upwards against the fixed die along with the soil within it as the movable die is pressed into it from below. A cam mechanism gradually increases the mechanical advantage toward the end of the stroke so that from 300N input force it can produce 80kN (which works out to, surprisingly, only 2MPa). By pivoting the whole mechanism onto a different cam follower, a second cam ejects the block from the top of the mold. He demonstrates a three-point bending test for fully cured blocks. I’m not a big fan of the expensive precision cylindrical movement joint used by this design, especially in an environment with sand. But I really like the idea of the interlocking blocks.
another #video on a #mechanical machine from Zhenting Machine in China costing several thousand dollars for interlocking #compressed-earth blocks for #construction. It measures the soil into the compression chamber, makes two bricks at a time, leaves hollow spaces in the bricks, and uses a hydraulic press for the compression the ejection, which is through an openable mold top like the #Blocco-Mattone machine. Although the compression work is done by a motor, the rest of the machine’s action is manual; the operator must run through a sequence of actions to make two bricks, taking about a minute — but preparing dirt is the bottleneck. The vertical and some horizontal corners of the bricks are chamfered, as are the interlocking studs, which are hollow. The horizontal corners on the ends of the brick are the ones which aren’t chamfered, an odd omission. They bought the 110VAC-powered model. (30 amps!!) Brick dimensions 300mm × 150mm × 115mm. 1½–2 buckets of dirt makes 6 bricks.
previous #video on #compressed-earth block #mechanical machine from Zhenting Machine, similar to #Blocco-Mattone machine. Ideally 10–15% portland, 30% clay. The AECT machine cost US$60k so they bought this US$5500 machine from Alibaba, “Eco Brava Burning Free Interlock” from “Shandong Weida Construction Machinery Co. Ltd.”.
Another #compressed-earth block #construction #mechanical machine #video, this one on “Verde Equipamentos” in Minas Gerais, with chamfers on 8 of the 12 cuboid edges and with hollow circular interlocking studs. No tongue and groove. This one is powered by muscle power with a toggle mechanism.
#compressed-earth blocks are supposed to be compressed with 21MPa, not 12MPa or 2MPa, which reduces the volume by half. Mentions that Raul Ramirez developed the Cinva Ram press in the 01950s driving a cam with a long lever, similar to the #Blocco-Mattone design.
#stealth-camping celebrity #Steve-Wallis livestreamed for an hour about the recent deaths of his wife Jess, his mother, and his best friend Glen, all of which could have been prevented by going to see a doctor; his baseless shame and guilt over his slipping YouTube productivity; his difficulty getting a passport; and his fruitless search for someplace that feels like home. “I’m not a YouTuber, I’m a furnace repairman.”
#electronics organ laser-cut from MDF and pink acrylic #video
#video by #gomezgimenez on #manufacturing a digital clock that works by illuminating falling sand at 10Hz, all initially controlled by an Arduino (maybe a Mega, not sure), though later he got his own board fabbed with an onboard micro, looks like a PIC18F4550 actually, then soldered the parts down with a solder-paste stencil and hotplate reflow. Demonstrates some interesting #manufacturing techniques, such as CNC-routing a PCB with a D-bit with auto-bed-leveling sensed by conduction to the (coppper-clad) workpiece. Standard captive-nut technique for screwing together FDM 3-D prints and PCBs. Not sure why each digit requires 4 pixel columns of sand instead of 3. Because he’s modulating the timing of the sand release with the (16!) solenoids rather than the timing of the light flashes, he doesn’t have to worry about leakage of light between columns. Unfortunately you’d need a higher refresh rate than 10Hz for this to be practical; a 10Hz flicker is maximally distracting. Also the sand runs out in two minutes. #electronics #hardware
#video of #gomezgimenez #manufacturing a solder-paste stencil for #electronics #hardware from an aluminum can. The cotton gloves for handling the aluminum are a good idea. He anneals it with a clothes iron on the high setting on a corkboard for 20 minutes, then removes the paint with acetone. First he tries photolithography with photoresist film. For a photomask he prints out three identical transparencies on a Brother laser printer and cyanoacrylate-glues them together. His UV source for exposing the photosensitive film is one of those nail-salon UV caves. 2% washing soda removes the unexposed film. Then he etches the aluminum with a commercial etchant of HCl and sodium persulfate (‽). To remove the exposed photoresist film and the inner epoxy liner of the Coca-Cola can he uses acetone. This produces somewhat uneven and rounded holes. Second, he tries milling with a “CNC 1419” desktop milling machine, using a 100μm conical milling cutter with a 30° included angle. His workholding is supergluing painter’s tape on the back of the aluminum to painter’s tape on a plywood spoilboard. (Stackup: plywood, stickum, paint backing, superglue, paint backing, stickum, aluminum can, air.) The calculated kerf is 207μm from the sum of the 100μm tip, the 200μm surface penetration, and the 30° included angle. FlatCAM ingests the Gerber and runs the mill. His cutting fluid is 3-in-1 oil. This one seems to be cut more precisely, though not quite as precisely as PCBWay’s laser-cut stainless stencil.
#video of #microcontroller #hardware, the #Puya PY32 Cortex-M0, with #pricing of 10¢ in quantity 500. Over ten minutes of worthless talking-head footage at the beginning of the video. 5.5 volts, reprogrammable. Part numbers sound like STM32F0 clones? PY32F0032A is 24MHz, 20KiB Flash, 3KiB SRAM, 18 GPIOs, 1 ADC, 3 timers, SPI, UART, I²C; the 30¢ PY32F030 has, among other things, 32KiB Flash, 8KiB RAM, and 48MHz; the 50¢ PY32F072 even has CAN and USB. You have to get them off LCSC. He’s using Keil and programming it with an ST-Link v2, and some people use Stm32Cube. Screenshots of py32.org, which still has Puran’s documentation for their chips. He’s only able to get the code to flash at 3.3V. He recommends reading the STM32 manual to learn how to set up the ADC, so I guess this really is an #STM32 clone. (He points at ST copyright notices in the BSD-licensed HAL source code.) He also recommends reading Puya’s example code in the zip file and the well-written PY32F030 series reference manual in English.
OpenPuya project for #Puya #microcontroller #hardware. “In order to make up for the untimely update of materials on the official website, we will serve as an unofficial repository, collecting product materials from #Puran Semiconductor Company.” Mostly only in Chinese!
this SOP-8 #Puya PY32F002 #microcontroller #hardware has #pricing of 8.26¢ in quantity 500. A 24MHz Cortex-M0(+?)
camping #video in the UK. Largely a review video for a big brown “cabin-style” tent with a fire-resistant mat where the wood stove goes. Hmm, this campfire in the middle of dry leaf litter seems ill-advised; he’s sawing firewood with his portable saw and splitting it with his camping knife. The folding camp table made out of tent poles is interesting. He demonstrated the TCES flameless ration heater used to cook a US MRE (powered by iron and magnesium). And then police were called — the week before, when he was cooking hotdogs in a fire pit with his dad, because a jogger saw them taking their shotgun out of the car into the woods. Their own woods! But not because of the cabin tent. #clickbait
#video of demodulating AM #radio with a hot dog, or rather plasma to the antenna tower from a grounded hot dog