Bitcoin’s Double Spending Flaw Was Hush-Hush During Rollout

October 2, 2018 by Pedro Umbelino 15 Comments

For a little while it was possible to spend Bitcoin twice. Think of it like a coin on a string, you put it into the vending machine to get a delicious snack, but if you pull the string quickly enough you could spend it again on some soda too. Except this coin is worth something like eighty-grand.

On September 20, the full details of the latest fix for the Bitcoin Core were published. This information came two days after the fix was actually released. Two vulnerabilities were involved; a Denial of Service vulnerability and a critical inflation vulnerability, both covered in CVE-2018-17144. These were originally reported to several developers working on Bitcoin Core, as well as projects supporting other cryptocurrencies, including ABC and Unlimited.

Let’s take a look at how this worked, and how the network was patched (while being kept quiet) to close up this vulnerability.

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Pirates Don’t Stand A Chance Against This 3-D Printed Pan-Tilt Gimbal

October 2, 2018 by Dan Maloney 11 Comments

Attention: No ~~pirates~~ maritime wealth redistribution agents were harmed in the making of the video below.

Some projects are for work, some are for fun, and some, like this entirely 3D-printed camera pan-tilt gimbal, start out as work and then turn into fun. As professional digital FX artist [FlorianH] tells the tale, he was in need of such a rig for some motion-control work. Buying off the shelf is always an option, except when it’s boring, so [Florian] invested an untold number of hours in front of Fusion 360 meticulously designing every last part, except for some bearings, the NEMA 17 steppers, and some fasteners. ~~Ten~~ One hundred hours of printing later and the device was ready for assembly and a quick test, which showed that this thing is smooth as silk.

And the pirate snuff-vid? That was just for fun, and we enjoyed it immensely. [Florian] assures us that none of the explosions were added in post; all are practical effects, done with flash cotton and a bit of powdered charcoal. We asked – you know, for reference.

We’ve featured lots of pan-tilt rigs before, using everything from hobby servos to purely mechanical linkages. But this one has a certain flair to it that we really like.

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Tiny WiFi-Enabled ARM MCU For Tiny Projects

October 2, 2018 by Maya Posch 62 Comments

Ever since the ESP8266 WiFi-enabled microcontroller came on the scene, it seemed like suddenly everyone came up with WiFi-enabled projects. But the ESP8266 is not the only game in town! Reader [PuceBaboon] notified us of a new product released by Seeed Studios: the imaginatively called Air602 WiFi Development Board.

The core of this board is the tiny WinnerMicro W600 MCU, which integrates a 32-bit ARM Cortex M3 CPU, along with dual UARTs, I2C, SPI and I2S interfaces, as well as a real-time clock (RTC). Add to this hardware crypto, seven I/O pins (five broken out on the development board) and you have a very capable WiFi-enabled MCU which can be programmed using the usual ARM development tools (e.g. Keil) using the provided SDK.

The W600 module can be bought by itself, in all its diminutive 12 mm x 10 mm glory, for a mere $1.90 as of time of writing – without antenna – as noted in [PuceBaboon]’s thoughts on this MCU and the development board.

VinylVideo Is Literally Video On Vinyl

October 1, 2018 by Drew Littrell 25 Comments

It’s often said that the music etched into a vinyl record takes on a transcendent quality that you simply can’t find in a digital recording, but does that still apply when you add motion picture? The collaboration of [Sengmüller and Diamant] sure think so, because they are offering a new experience for the turntable with the introduction of their VinylVideo pre-amplifier. No tape reels here, this project shows the extend of what is possible through analog video.

While all record players capable of playing back 7 in. 45 RPM are compatible with the system, the VinylVideo records themselves specially cut in order to generate the video signal. Each of the custom records has room for a 4-minute music video on the A-side, and the single on the B-side. Videos play back in black & white, sub-standard definition with mono audio, and run around 12 frames per second. The pre-amp takes in the analog signal from regular audio cables via RCA jacks or 3.5mm headphone jack, and then a Raspberry Pi model A+ handles the analog-to-digital conversion. Video out options include HDMI and composite video via a 3.5mm TRSS jack.

The current VinylVideo pre-amp is actually a refinement of the original project from the mid ’90s where it was a part of folk art exhibits. The legacy website (circa 1999) is still live, so you can give it a visit. However, for the most authentic experience you may want to fire-up a virtual machine with Netscape Navigator and Real Player installed.

For a more in-depth look at the VinylVideo in action there is a great video below from [Techmoan]:

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inside shot of a refrigerator with water bulk tank and seltzer pump

Continuous Seltzer Deployment System Solves Our Bubbly-Water Sourcing Problems

October 1, 2018 by Brian Boucheron 19 Comments

Seltzer water – that bubbly, carbonated water that disappoints sugar-craving children everywhere – has experienced a steady rise in popularity over the past few years. This is perhaps partly fueled by the availability of countertop carbonators such as the SodaStream.

Not satisfied with the tedious and pedestrian process of manually carbonating individual bottles of water, [piyoman] has instead built a tidy little tap of unlimited cold, filtered seltzer. It’s no easy gag. The build uses a commercial carbonator pump, reverse osmosis water filter, bulk tank, and a standard CO2 cylinder to create a constant source of carbonated water. Most of this setup is stuffed into a dorm-sized fridge (tetris-style) and topped with a fancy beer faucet to dispense the resulting bubblewater.

At roughly $800 for the documented system, you need to have a great reason to build your own. But [piyoman] provides detailed instructions, a parts list, and suggestions for cost savings and future improvements if you do take on a system like this for your seltzer needs.

Cheaper Carbonation Options

While looking at how DIY carbonation has been done in the past we found [Richard Kinch’s] Carbonating at Home with Improvised Equipment and Soda Fountains page which dives into many other options. His site – a wonderful, dense demonstration of the beauty of “web 1.0” – walks through the basics of carbonated water, discusses CO2 tanks and gauges, and shows how to build a simple carbonation cap for making seltzer in standard PET soda bottles.

Add Some Edge To Your Blades With Blown-Arc Plasma

October 1, 2018 by Dan Maloney 8 Comments

If you polled science fiction fans on what piece of technology portrayed by the movies that they most desire, chances are pretty good that the lightsabers from the Star Wars franchise would be near the top of the list. There’s just something about having that much power in the palm of your hand and still needing to be up close and personal to fight with it. Plus being able to melt holes in bulkheads is pretty keen, as are the cool sounds.

Sadly, the day we can shape and contain plasma in a blade-shaped field is probably pretty far off, but that didn’t stop [Alan Pan] from trying the next best thing: a handheld plasma-projecting blade. He starts with a basic Jacob’s ladder. We’ve seen many of these before, but the basic idea is to ionize the air between two parallel, vertical conductors; the hot plasma heats the air causing it to rise until it reaches the top and snuffs itself out, starting the process over again at the bottom. His twist is to force the plasma into a sheet between the electrodes with air from a leaf blower, forming a blown-arc plasma. That’s pretty cool looking by itself, but he also stretched the electrodes along razor-sharp wood planer blades, for extra danger. We have to admit that the thing looks pretty intimidating, even if the plasma doesn’t really pack bulkhead-melting thermal power. Check out the results in the video below.

We’d love to see [Alan] make good on his promise to make the whole thing self-contained with an electric ducted fan or mini jet engine. Even as it is, it’s still pretty neat. It’s not really his first lightsaber rodeo, but at least this one doesn’t need butane.

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High Detail 3D Printing With An Airbrush Nozzle

October 1, 2018 by Tom Nardi 38 Comments

On a fused deposition modeling (FDM) 3D printer, the nozzle size dictates how small a detail you can print. Put simply, you can’t print features smaller than your nozzle for the same reason you’d have trouble signing a check with a paint roller. If the detail is smaller than the diameter of your tool, you’re just going to obliterate it. Those who’ve been around the block a few times with their desktop 3D printer may have seen this come up in practice when their slicer refused to print lines which were thinner than the installed nozzle (0.4mm on the vast majority of printers).

Smaller nozzles exist for those looking to improve their printer’s detail on small objects, but [René Jurack] wasn’t happy with just putting a finer nozzle on a stock E3D-style hotend. In his opinion it’s still a hotend and arrangement intended for 0.4mm printing, and doesn’t quite fully realize the potential of a smaller diameter nozzle. After some experimentation, he thinks he’s found the solution by using airbrush nozzles.

As [René] sees it, the hotend is too close to the subject being printed when using nozzles finer than 0.4mm. Since you’re working on tiny objects, the radiant heat from the body of the hotend being only a few millimeters away is enough to deform what you’re working on. But using the long and tapered airbrush nozzle, the hotend is kept at a greater distance from the print. In addition, it gives more room for the part cooling fan to hit the print with cool air, which is another critical aspect of high-detail FDM printing.

Of course, you can’t just stick an airbrush nozzle on your E3D and call it a day. As you might expect, they are tiny. So [René] designed an adapter that will let you take widely available airbrush nozzles and thread them into an M6 threaded hotend. He’s now selling the adapters, and judging by the pictures he posted, we have to say he might be onto something.

If you’re more about brute strength than finesse, you might be interested in outfitting your E3D with a ruby nozzle instead.

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