I Am NXT 3-Point Bend Tester. Please Insert Girder.

Learning with visuals can be very helpful.  Learning with models made from NXT Mindstorms is just plain awesome, as [Rdsprm] demonstrates with this LEGO NXT 3-point bend tester that he built to introduce freshmen to flexural deflection and material properties. Specifically, it calculates Young’s modulus using the applied force of a spring and the beam’s deflection. [Rdsprm] provides a thorough explanation in the About section of the YouTube video linked above, but the reddit comments are definitely a value-add.

[Rdsprm] built this from the Mindstorms education base set (9797) and the education resource set (9648). Each contestant endures a 5-test battery and should produce the same result each time. The motor in the foreground sets the testing length of the beam, and the second motor pulls the spring down using a gearbox and chain.

This method of deflection testing is unconventional, as [Rdsprm] explains. Usually, the beam is loaded incrementally, with deflection measured at each loading state. Here, the beam is loaded continuously. Vertical deflection is measured with a light sensor that reads a bar code scale on the beam as it passes by. The spring position is calculated and used to determine the applied force.

[Rdsprm] analysed the fluctuation in GNU Octave and has graphs of the light sensor readings and force-deflection. No beams to bend with your Mindstorms? You could make this Ruzzle player instead.

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NeverWet On Electronics?

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Does NeverWet work on electronics? The team over at Adafruit just had to find out — and to an extent, it does work!

But wait, what’s NeverWet? It’s Rust-Oleum’s miracle water-repelling coating which is super hydrophobic. It actually works, and we’re kind of surprised we haven’t seen it used in a hack yet! Anyway, let’s start this hack with a quick disclaimer. NeverWet is not designed for waterproofing electronics.

But when has that ever stopped the pursuit of science!?

The experimenters chose a few electronic guinea pigs to test out NeverWet’s capabilities. An Arduino Micro, a FLORA LED broach, and a Raspberry Pi. Using the proper application method they coated the unlucky electronics with a few generous layers of the product. Using plain NYC tap water they tested each component. The FLORA LED broach (shown above) lasted underwater for about 4 hours before it died. The Arduino Micro fared similar, however the Wet Raspberry only booted once before losing connection to the SD card.

For full details check out the full experiment or stick around after the break to see a video of the tests.

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Direct, Wall-Mounted Storage With Lasers And Polymorph

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We’re sure everyone could use some more storage and organization in their workshop. [Nixie] is no exception, though he also hates sacrificing tabletop space for boxes. His solution was to attach them to the wall directly by hacking together some brackets. This hack allowed him to hang everything without using internal screws which were a pain to get at if he need to removed the boxes from the wall to take with him.

[Nixie] started by laser-cutting a negative pattern for a mounting bracket that would fit the dovetail rails already on the sides of the boxes. He then pressed a piece of polymorph into this mold, slid the bracket along the side of the box…and realized it wouldn’t work. The piece wiggled around too much because it did not sit firmly in the rail. Back at the drawing board, [Nixie] split the project into two steps. He cast the screw-hole portion of the bracket in its own separate mold, then cast the railing part of the bracket directly in the dovetail section of the box, providing him a much higher degree of accuracy. After joining the two pieces, [Nixie] had a sturdy support bracket that he duplicated and attached around the rest of the bins.

Impersonating FBI Agents And People Who Can Solder

[Dale Botkin], [N0XAS], is a competent designer for the amateur radio crowd and has a part-time business on the side selling a few kits. As anyone who owns a business, works in retail, or simply interacts with the general population will know, eventually you’ll have to deal with one of those customers. [Dale]’s latest horror story (here’s the coral cache but that doesn’t seem to be working either) comes from someone who bought a little repeater controller. You’re looking at this customer’s handiwork above. It gets worse.

After this customer completely botched an assembly job, he contacted [Dale] for some technical assistance. [Dale] graciously accepted a return and received the above mess of solder, wires, and parts. Then an email disputing the Paypal charge arrived. The customer wanted a refund for the original kit and the cost of shipping it back.

Oh, but it gets better. After posting this story, [Dale] received yet another email from an FBI agent demanding that his original post be taken down. The email from the FBI came from a Czech domain, so of course this is a totally legit demand.

So there’s your, “worst customer ever” story from the world of kit electronics. The assembly is impressively bad, even for something that was ‘professionally installed by an electrician’, but mail fraud and impersonating federal officials just takes this over the top.


Quick note: any doxxing in the comments will be deleted, so just don’t do it.

Ambient Computer Noise Leaks Your Encryption Keys

[Daniel, Adi, and Eran], students researchers at Tel Aviv University and the Weizmann Institute of Science have successfully extracted 4096-bit RSA encryption keys using only the sound produced by the target computer. It may sound a bit like magic, but this is a real attack – although it’s practicality may be questionable. The group first described this attack vector at Eurocrypt 2004. The sound used to decode the encryption keys is produced not by the processor itself, but by the processor’s power supply, mainly the capacitors and coils. The target machine in this case runs a copy of GNU Privacy Guard (GnuPG).

During most of their testing, the team used some very high-end audio equipment, including Brüel & Kjær laboratory grade microphones and a parabolic reflector. By directing the microphone at the processor air vents, they were able to extract enough sound to proceed with their attack. [Daniel, Adi, and Eran] started from the source of GnuPG. They worked from there all the way down to the individual opcodes running on the x86 processor in the target PC. As each opcode is run, a sound signature is produced. The signature changes slightly depending on the data the processor is operating on. By using this information, and some very detailed spectral analysis, the team was able to extract encryption keys. The complete technical details of the attack vector are available in their final paper (pdf link).

Once  they had the basic methods down, [Daniel, Adi, and Eran] explored other attack vectors. They were able to extract data using ground fluctuations on the computers chassis. They even were able to use a cell phone to perform the audio attack. Due to the cell phone’s lower quality microphone, a much longer (on the order of several hours) time is needed to extract the necessary data.

Thankfully [Daniel, Adi, and Eran] are white hat hackers, and sent their data to the GnuPG team. Several countermeasures to this attack are already included in the current version of GnuPG.

A Weird Kind Of Printer

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[Benjamin] is just putting the finishing touches on his home-made, paper-stabbing, needle-printer!?

From a distance, it looks like the bare bones of a regular inkjet printer, but it’s not. Instead of an ink-head it features a needle — It’s kind of like a dot-matrix (hole-matrix?) printer. He’s using it for silk-screening masks, which we have to admit, must be pretty handy — it certainly makes soldering SMT’s less scary! It could also be used for embossing or even braille printing.

The frame of the printer is laser cut out of clear plastic, and two Nema 17 steppers drive the X & Y axes. A simple solenoid actuator provides the needle-stabby action. He’s controlling the whole thing using an Arduino, and sending the data to it using a call-and-response protocol to avoid any data losses. It was built for just shy of $200, which was his original goal for the project.

Check it out after the break!

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Thermochromic Imaging

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[clarii_d] is currently finishing up her thesis project on thermochromic pigment to silkscreen receipts. The idea behind it is that when a receipt is touched, part of it fades revealing a hidden message.

As you can guess, thermochromic paint is a type of substance that changes color when introduced to heat — or in this case, fades altogether. Remember when mood rings were all the rage? Same thing.

In her project she is using silkscreening to transfer text onto the back of receipt paper using regular ink. Once dried, she silkscreens an image over top of the message, this time using a thermochromic pigment. The result is a slightly obscured image, but after holding it for a few seconds, it disappears and only the text remains.

Color-changing anything is a bit gimmicky, but we think [clarii_d’s] project is a pretty cool and unique application of it. A few years ago we shared another interesting project utilizing thermochromism; a color-changing clock face that utilized the heat given off by resistors!