This Power Strip Is A Fire Starter

October 27, 2017 by Adam Fabio 114 Comments

A few weeks ago I needed a power strip in my home office. The outlet in question is located behind a filing cabinet so it would need a low profile plug. I jumped on Amazon to buy a surge suppressor strip. That’s when I noticed strips with rotating plugs. I’ve always had some apprehensions about plugs like that, though I could never quite put my finger on why. Looking at the reviews on this particular plug, I found some scary issues. Photos of melted plugs, melted outlets, and cries of “fire hazard”. So I did what any crazy hacker would do – bought two power strips. One with a fixed right angle plug to use in my office, and one with a rotating plug to tear down.

Surge suppressors, power strips, outlet strips, they have many names. Underwriter’s Laboratories (UL) calls them “Relocatable power taps”. They all have several outlets, most have a circuit breaker of some sort inside, and some have circuits for surge suppression. These are some of the most common devices to find in the modern home. Many of our houses were designed and built before surround sound, cable boxes, computers, modems, cell phone chargers, tablet chargers, and all our other modern conveniences. There weren’t as many electrical loads, so the houses didn’t have many outlets. Power strips solve this problem.

After a couple of days, I had my strips in hand. I expected the plug to rotate once – maybe 270 degrees. That would indicate there were wires connecting the rotating head to rest of the plug. Not so – this plug would spin round and round all day long.

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DIY Barometer: It’s For Your Health!

October 27, 2017 by James Hobson 13 Comments

[Taciuc Marius] and his colleague noticed that days with low atmospheric pressure plus caffeine in their system meant a spike in blood pressure. Considering how this might impact his cardiovascular health, he decided to make a relative pressure barometer out of a jar to help him decide whether he should really have another cup of coffee.

Aside from a 3D printer, you’ll need to assemble a small jar with a lid, some screws, lock washers, nuts, and a flexible membrane — a piece of a rubber glove or balloon will do nicely. [Marius] details the build process on his project page, advising others to print the parts at 0.2 resolution — potentially even upping the extrusion multiplier to 1.1 — to prevent gaps in the print that would compromise the airtight seal needed for the barometer to work properly.

Additionally, thick glue or epoxy is recommended for the rest of the assembly process — it doesn’t have to be pretty, but it does need to be sealed! The final product can be easily tested by simply holding the jar.

While this barometer helps one make healthy choices, not all are created equal. This one tells you flat out how you should consider getting to work, while others have been tricked into behaving like touch sensors.

How To Bend PVC The Nice Way

October 27, 2017 by Lewin Day 32 Comments

PVC pipe is a valuable material to the backyard hacker. It’s cheap, readily available, and comes in a range of different sizes. However, what do you do if you need to bend it? The typical approach would be to grab a heat gun or blowtorch, warm it up, and go from there. These methods can get messy however, with kinks and melted surfaces spoiling the final result. Now [Linn] has released a video with a method that delivers impressively neat results.

A bending jig can help create repeatable results.

The method is simple, using that classic hacker staple — duct tape. The end of the pipe is taped off, and the pipe filled with sand. With the correct amount measured out, the sand is heated on a cooktop, then poured back into the pipe. After giving the heat some time to soften the plastic, the pipe can then be manipulated into the desired shape.

[Linn] does a great job of explaining the process in a clear and concise manner, and shares tips on how to use a bending jig to guide the final shape. Results are best with smaller pipes that are easier to heat through, but larger sections can be manipulated with patience.

We can’t wait to see what [Linn] builds with this new technique. The possibilities could be further expanded by combining with these PVC fittings designed just for building stuff.

[Thanks to George for the tip!]

Skynet Will Have Bobcats

October 26, 2017 by Pedro Umbelino 40 Comments

There are so many autonomous devices nowadays that can run Skynet Inside^(TM) that it’s hard to keep track. But one was still missing: the versatile Bobcat. When we say “Bobcat”, we mean track loader — it’s just one of those things that the name and the brand stoke together so strongly that it’s hard to actually recall the technical name. A company by the name of Built Robotics is betting on autonomous track loaders as being a big part of the future of construction.

The tractor can navigate, excavate, and carry a 1,000 pound load with 1 cm precision using its LIDAR, specially designed to work with high-vibration, high-impact environment of construction excavation. Additionally, the lasers also allow the robot to measure the amount of material it has scooped up. But the precision does not come from the LIDAR alone. To position the robot, Built Robotics uses augmented GPS, which combines an on-site base station and GPS satellites to produce accurate location data.

It is supposed to be completely autonomous: given a location and holes to dig, it can plan and execute the work. It resembles a self-driving car, but the challenges are actually quite different. Cars are mean to drive around and reach a destination without touching anything. Like the CEO of Built Robotics says:

“If a car is changing the environment around it, then something’s gone really wrong.”

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Hollow State Memory

October 26, 2017 by Al Williams 12 Comments

A lot of people like tubes either for their audio sound or their collectible value. [Uniservo] likes oddball tubes. His recent video (see below) shows a radechon — a computer memory tube. These were apparently widely used in RADAR sets until recently and has some similarity to a Williams tube.

The tube is essentially a CRT that illuminates a sheet of mica or another dielectric instead of a phosphor screen. The dielectric has a fine mesh grid in contact with it. By depositing charge on the mica, the tube can store an analog value. In theory, the tube could store about 16 kbits of information, but in practice, the resolution was less.

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Thermite Creates A Sword

October 26, 2017 by Brian McEvoy 26 Comments

Thermite can cut cars in half but [TheBackyardScientist] relies on its ability to create rather than destroy. In fact, thermite was the key component when he casts a solid metal sword. The casting doesn’t require a furnace since the heat is produced by the thermite itself.

In case it wasn’t abundantly clear: this procedure is not without risk.

[TheBackyardScientist] compares two types of iron oxide, red and black, then judges their usability based on the post-ignition mass. His goal is to get the most metal from a single reaction. He also adds some stainless steel beads to improve the quality of the casting and to utilize some of the excess heat.

With encouragement from his neighbors and a couple of trials with fire bricks, buckets, and sand, [TheBackyardScientist] is successful. The resulting sword is treated, given a handle, sharpened, then scientifically tested with a variety of things found in a regular kitchen.

If you look in the background of [TheBackyardScientist]’s workshop, you may notice his molten PEWter gun. This steel sword is an upgrade from his recycled pewter sword a few years ago.

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Reconstructing A Blurry QR Code

October 26, 2017 by Lewin Day 4 Comments

QR Codes are a two-dimensional type of matrix barcode that are used for a variety of uses. They’re one way of turning a long piece of string data into an easily machine-readable format. For this reason, they can be used to store private keys for encryption and crypto-currency purposes. [Roger Ver] attempted to use a QR code containing a private key to give away some cryptocurrency on TV, but the code was blurred out by the broadcaster. Not ones to give up easily, [Michael] and [Clément] decided to see if they could reconstruct it anyway.

The work begins, as so many cryptographic exploits do, with the collection of as much of the plaintext key as possible. By stepping through the footage frame by frame, small pieces of the unobscured QR code were found, as well as some of the private key itself. By combining this with enhanced images of the blurred code, the team were able to put together less than one third of the QR code. The team had other tricks up their sleeve though – they knew the QR contained a private key of a particular format, and were able to figure out the QR code was 41×41 pixels.

By using this data along with a careful study of the QR code format, the team were able to put together some code in Python to brute force the key. After 838849 trials, the key was found, and the team were able to claim the prize. It’s a great example of cryptographic analysis – and so is this story on hacking your own password.

[Thanks to Esko for the tip!]