To Kill A Blockchain, Add Naughty Stuff To It?

March 25, 2021 by 65 Comments

Even if not all of us are blockchain savants, we mostly have a pretty good idea of how they function as a distributed database whose integrity is maintained by an unbroken chain of conputational hashes. For cyryptocurrencies a blockchain ledger stores transaction records, but there is no reason why the same ledger can not contain almost any other form of digital content. [Bruce Schneier] writes on the potential consequences of content that is illegal or censored being written to a blockchain, and about how it might eventually form a fatal weakness for popular cryptocurrencies.

It’s prompted by the news that some botnet operators have been spotted using the Bitcoin ledger to embed command and control messages to hide the address of their control server. There have already been cases of illegal pornography being placed within blockchain ledgers, as well as leaked government data.

[Schneier] uses these two content cases to pose the question as to whether this might prove to be a vulnerability for the whole system. If a government such as China objects to a block containing censored material or a notoriously litigious commercial entity such as Disney objects to a piece of copyrighted content, they could take steps to suppress copies of the blockchain that contain those blocks. Being forced by hostile governments or litigious corporations to in effect remove a block from the chain by returning to the previous block would fork the blockchain, and as multiple forks would inevitably be made in this way it would become a threat to the whole. It’s an interesting possible scenario, and one that should certainly be ready by anyone with an interest in blockchain technologies.

Only a few weeks ago we looked at another threat to blockchain technologies – that they might be legislated out of existence by environmental rules.

A Raspberry Pi Tablet, With A DSI Screen

March 24, 2021 by 36 Comments

Since the Raspberry Pi arrived back in 2012, we’ve seen no end of interesting and creative designs for portable versions of the little computer. They often have problems in interfacing with their screens, either on the very cheap models using the expansion port or on more expensive ones using an HDMI screen with associated controller and cabling. The official Raspberry Pi touchscreen has made life easier with its DSI convector, but as [jrberendt] shows us with this neat little tablet, there are other DSI-based options. This one uses a 5″ DSI touchscreen available through Amazon as well as a Pi UPS board to make a tablet that is both diminutive and self-contained.

Having fooled around ourselves in the world of Pi tablets we like this one for its clean look and a bezel that is little bigger than the screen itself. As is the case with so many Pi tablets though it has to contend with the bulk of a full-sized Model B board on its behind, making it more of a chunky brick than a svelte tablet. The screen has potential though, and we can’t help wondering whether there’s any mileage in pairing it with a much thinner Pi Zero board and a LiPo board for a slimmer alternative.

Probably the nicest Pi tablet we’ve brought you was this one, which managed to remain impressively slim despite its HDMI screen.

PCTG Filament Has Interesting Properties

March 24, 2021 by 37 Comments

Early 3D printers used ABS, but bad fumes and warping made most people go to PLA. However, PETG has a lot of the great properties of ABS along with some of the ease-of-use of PLA. According to a recent [VisionMiner] video, however, PCTG — Polyethylene Terephthalate-Glycol — could be the next filament of choice. The filament itself is from Essentium, but it appears that [VisionMiner] is a reseller of the filament (along with other engineering plastics). Thus the video below has a bit of marketing speak in it, but it also has good information and examples of using PCTG.

The plastic is relatively inexpensive, but still not as cheap as PLA or even PETG. A 750g roll is about $40 The benefits? According to the video, this plastic is stronger, tougher, and clearer than other common options.

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Coil Winding Machine Makes It Easy

March 24, 2021 by 19 Comments

[Mr Innovative] needed to wind some coils, and decided to make a machine to do the work. Making such machines has become a lot easier over the years. There was a time when we might probably have had to hack an old printer or scanner to get linear rods and stepper motors. Now, thanks to widespread 3D printing, we can order parts like that from lots of places. The 3D printing helps, too, to fabricate all the little custom widgets you need to put something like that together.

The machine looks great. It uses a number of parts that would look at home on a 3D printer or CNC build. We thought his Chinese mini table saw did a great job cutting the aluminum extrusions, but we did worry about the safety of his fingers. We’ll admit we are generally lazy and buy the extrusions precut.

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A Simple But Effective High-Flow Oxygen Concentrator From Hardware Store Parts

March 24, 2021 by 76 Comments

To say that a lot has happened in the year since the COVID-19 pandemic started is an understatement of epic proportions, so much so that it may be hard to remember how the hardware hacking community responded during those early days, with mass-produced PPE, homebrew ventilators and the like. But we don’t recall seeing too many attempts to build something like this DIY oxygen concentrator during that initial build-out phase.

Given the simplicity and efficacy of the design, dubbed OxiKit, it seems strange that we didn’t see more of these devices. OxiKit uses zeolite, a porous mineral that can be used as a molecular sieve. The tiny beads are packed into columns made from hardware store PVC pipes and fittings and connected to an oil-less air compressor through some solenoid-controlled pneumatic valves. After being cooled in a coil of copper pipe, the compressed air is forced through one zeolite column, which preferentially retains the nitrogen while letting the oxygen pass through. The oxygen stream is split, with part going into a buffer tank and part going into the outlet of the second zeolite column, where it forces the adsorbed nitrogen to be released. An Arduino controls the valves that alternate the gas flow back and forth, resulting in 15 liters per minute of 96% pure oxygen.

OxiKit isn’t optimized as a commercial oxygen concentrator is, so it’s not particularly quiet. But it’s a heck of a lot cheaper than a commercial unit, and an easy build for most hackers. OxiKit’s designs are all open source, but they do sell kits and some of the harder-to-source parts and supplies, like the zeolite. We’d be tempted to build something like this just because the technology is so neat; having a source of high-flow oxygen available isn’t a bad idea, either.

30-Year-Old Macintosh SE/30 Gets A Brand New Logic Board

March 24, 2021 by 36 Comments

Some time ago, [Bolle] got the idea to redraw the Macintosh SE/30 schematics in Eagle. Progress was initially slow, but over the past month (and with some prodding and assistance from fellow forum frequenter [GeekDot]), he’s taken things a step further by creating a fully functional replacement Macintosh SE/30 logic board PCB.

By using the available schematics, the project didn’t even require much reverse engineering. Though he plans for more modernization in later iterations, this design is largely faithful to the original components and layout, ensuring that it is at least basically functional. He did update the real time clock battery to a CR2032 and, as a benefit of redrawing all the traces, he was able to use a 4-layer PCB in place of the costly 6-layer from Apple’s design.

The board came back from fabrication looking beautiful in blue; and, once he had it soldered up and plugged in, the old Mac booted on the very first try! A copy-paste mistake with the SCSI footprints led to some jumper wire bodging in order to get the hard drive working, but that problem has already been fixed in the next revision. And, otherwise, he’s seen no differences from the original after a few hours of runtime.

Recreating old Macintosh logic boards almost seems like its own hobby these days. With the design and fabrication capabilities now accessible to hobbyists, even projects that were once considered professional work are in reach. If you’re interested in making your own PCB designs, there are many resources available to help you get started. Alternatively, we have seen other ways to modernize your classic Macs.

[Thanks to techknight for the tip!]

Ask Hackaday: How Do You Prepare?

March 24, 2021 by 140 Comments

Last month, large parts of the southern United States experienced their coldest temperatures since the 1899 Blizzard. Some of us set new all-time lows, and I was right in the middle of the middle of it here in Southwestern Oklahoma. Since many houses in Texas and Oklahoma are heated with electricity, the power grids struggled to keep up with the demand. Cities in Oklahoma experienced some short-term rolling blackouts and large patches of the Texas grid were without power for several days. No juice, no heat.

In places where the power was out for an extended period of time, the water supply was potentially contaminated, and a boil order was in effect. Of course, this only works when the gas and power are on. In some places, the store shelves were empty, a result of panic buying combined with perishables spoiling without the power to keep them cold. For some, food and drinkable water was temporarily hard to come by.

There have been other problems, too. Houses in the south aren’t built for the extreme cold, and many have experienced frozen pipes, temporarily shutting off their water supply. In some cases, those frozen pipes break open, flooding the house once the water starts flowing again. For instance, here’s an eye-witness account of the carnage from The 8-bit Guy, who lives at ground zero in the DFW area.
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