[Piffpaffpoltrie] had a 20-year-old Acer flatbed scanner that they just couldn’t justify keeping. But it does seem a shame to throw away a working piece of gear. Instead, the old scanner became a light table. We’ll admit, as projects go, it isn’t the most technically sophisticated thing we’ve ever seen, but we do think it is a worthy way to upcycle something that would otherwise be filling up a landfill.
The scanner was old enough to have a CCFL light source inside. However, it was too small, so it came out along with many other components that may yet find use in another project. If you didn’t know , scanners are good sources for small stepper motors, straight rods, and first-surface mirrors.
The visual arts are a broad field, encompassing everything from the chiselling of marble sculptures to the creation of delicate landscapes in charcoal on paper. However, [Evelyn Rosenberg] has experimented with some altogether more radical techniques over the years, creating her explosively-formed detonographs.
The process of creating a detonograph starts with sketching out a design, and using it to create a plaster mold. The mold exists as a bas relief, upon which metal sheets are laid on top. Various different metals may be layered up to create varying effects, and other objects like leaves, branches, or lace may also be included in the stack up.
Rosenberg’s piece titled “Enchanted New Mexico.”
Then, the metal plate sitting atop the mold is covered with explosive powder. When this is detonated, it smashes everything together with great force. The metal sheet takes on the negative form of the bas relief mold, while also picking up imprints from any leaves or other objects included in the various layers. Dissimilar metals included in the stack-up may also weld together during this process.
With some post-processing like polishing and chemical treatments, the result is a beautiful metal artwork full of dimension and detail. It’s somewhat like an artistic take on the industrial process of explosive welding. Video after the break.
What’s the size of an AA battery and can run an ARM Cortex M0+ for six months? Well… probably an AA battery, but obviously, that wouldn’t be worth mentioning. But researchers at Cambridge have built a cell of blue-green algae that can do the job.
As you might expect, the algae need light, since they generate energy through photosynthesis. However, unlike conventional solar cells, the algae continue to produce energy in the dark at least for a while. Presumably, the algae store energy during the day and release it at night to survive naturally-occurring periods of darkness.
Generating power from photosynthesis isn’t a new idea since photosynthesis releases electrons. A typical cell has gold electrodes and a proton exchange membrane of some kind. You can see a video from Cambridge below about generating electricity from photosynthesis. Keep in mind, of course, that the Cortex M0+ is capable of very low power operation. Don’t look for that algae-powered spot welder anytime soon.
People tend to get fixated on electricity as energy, but there are other ways to harness photosynthesis. For example, we’ve seen algae fueling a chicken hole in the past. Not to mention we’ve seen algae used to power a robot in a novel and non-electrical way.
Guitars are most typically built out of wood. Whether it’s an acoustic guitar with a big open cavity, or a solid-body electric, there’s generally a whole lot of wood used in the construction. However, [Mattias Krantz] shows us that alternative construction methods are entirely possible, by building his own balloon guitar.
The balloon guitar still has a neck, bridge, and strings just like any other. However, in place of the resonant cavity of an acoustic guitar, there is provision to install a large balloon instead. It’s actually quite interesting to watch — with the balloon installed, the guitar delivers much more volume than when played without a resonant cavity at all.
The guitar was actually built to test if swapping out air in the balloon for helium would shift the pitch of the sound. Of course, a guitar’s pitch comes from the tension on the vibrating strings, so changing the gas in the resonant cavity doesn’t directly affect it. Instead, much like inhaling helium to affect the human voice, the change is to the timbre of the sound, not the fundamental pitch itself. It sounds as if the guitar has been given a subtle treble boost.
It’s a fun build, and one that shows us that it’s possible to build musical instruments in many ways, not just using traditional techniques. If you want to further play with your guitar’s sound, though, consider turning to the world of machine learning.
Between the era of the CD and the eventual rise and domination of streaming music platforms, there was a limbo period of random MP3 players mixed in with the ubiquitous (and now officially discontinued) iPod. In certain areas, though, the digital music player of choice was the MiniDisc, a miniature re-writable CD player with some extra digital features. Among them was the ability to transfer music to the discs over USB, but they did not feature the ability to transfer the songs back to a computer. At least until now, thanks to this impressive hack from [asivery].
Although it sounds straightforward, this trick has a lot of moving parts that needed to come together just right. The MiniDisc player uses a proprietary encoding format called ATRAC, so a codec is needed for that. The MiniDisc player stores data from the disc in a 40-second buffer when playing, so the code reads the data directly from DRAM in 40-second chunks, moves the read head, repeats the process as needed, then stitches the 40-second parts back together. It can work on any Sony NetMD portable, if you are lucky enough to still have one around.
The project is a tremendous asset to the MiniDisc community, especially since the only way to recover data from a MiniDisc player prior to this was to use a specific version known as the RH-1. As [asivery] reports, used RH-1 players are going for incredibly high prices partially because of this feature. Since this new method demonstrates that it’s possible to do with other devices, perhaps its reign in the MiniDisc world will come to a close. For those still outside the loop on this esoteric piece of technology, take a look at this MiniDisc teardown.
[Li Zhang] and his colleagues at the Chinese University of Hong Kong (CUHK) have developed a blob of goo that can navigate complex surroundings, grow an ‘arm’, grasp a wire and move it, encapsulate a small object and carry it. As explained in the research paper, the secret is in the non-Newtonian material the bots are made of.
You can make a similar concoction at home, usually called “slime”, with corn starch and water. Deformed slowly, it will move like a fluid. Deformed rapidly, it behaves like an elastic solid. CUHK’s version is polyvinyl alcohol, glass coated NdFeB microparticles (neodymium magnets), and borax.
This dual behavior lets the robot do amazing things. Placed on a surface, they made the blob extend pseudopods by dragging underneath with a magnet, then used a circular field to make it grasp and transport a wire. They used a similar technique in the other axis to swallow an object. The CUHK group are promoting this as a way to retrieve foreign objects in the body (like an accidentally swallowed button cell).
Researchers will need to develop a non-toxic coating before it can be used in the body.
Nd magnets are made by sintering Nd2O3 or NdFeB in a strong magnetic field. Nd2O3 is available from SigmaAldrich at only slightly eye watering prices. Polyvinyl alcohol and borax are easily available. This seems like a hobbyist do-able project (Nd is toxic, use precautions).
The team from the Sensing, Interaction & Perception Lab at ETH Zürich, Switzerland have come up with TapType, an interesting text input method that relies purely on a pair of wrist-worn devices, that sense acceleration values when the wearer types on any old surface. By feeding the acceleration values from a pair of sensors on each wrist into a Bayesian inference classification type neural network which in turn feeds a traditional probabilistic language model (predictive text, to you and I) the resulting text can be input at up to 19 WPM with 0.6% average error. Expert TapTypers report speeds of up to 25 WPM, which could be quite usable.
Details are a little scarce (it is a research project, after all) but the actual hardware seems simple enough, based around the Dialog DA14695 which is a nice Cortex M33 based Bluetooth Low Energy SoC. This is an interesting device in its own right, containing a “sensor node controller” block, that is capable of handling sensor devices connected to its interfaces, independant from the main CPU. The sensor device used is the Bosch BMA456 3-axis accelerometer, which is notable for its low power consumption of a mere 150 μA.
User’s can “type” on any convenient surface.
The wristband units themselves appear to be a combination of a main PCB hosting the BLE chip and supporting circuit, connected to a flex PCB with a pair of the accelerometer devices at each end. The assembly was then slipped into a flexible wristband, likely constructed from 3D printed TPU, but we’re just guessing really, as the progression from the first embedded platform to the wearable prototype is unclear.
What is clear is that the wristband itself is just a dumb data-streaming device, and all the clever processing is performed on the connected device. Training of the system (and subsequent selection of the most accurate classifier architecture) was performed by recording volunteers “typing” on an A3 sized keyboard image, with finger movements tracked with a motion tracking camera, whilst recording the acceleration data streams from both wrists. There are a few more details in the published paper for those interested in digging into this research a little deeper.
