Sundials, one of humanity’s oldest ways of telling time, are typically permanent installations. The very good reason for this is that telling time by the sun with any degree of accuracy requires two-dimensional calibration — once for cardinal direction, and the other for local latitude.
Switch it on, set it down, and the sundial spins around on a continuous-rotation servo until the HMC5883L compass module finds the north-south orientation. Then the GPS module determines the latitude, and a 180° servo pans the plate until it finds the ideal position. Everything is controlled with an Arduino Nano and runs on a 9V battery, although we’d love to see it run on solar power someday. Or would that be flying too close to the sun? Check out how fast this thing calibrates itself in the short demo after the break.
Is your heaving pile of electronic parts shrinking by the day as you finish old back-burnered projects and come up with new ones? Try an old pastime that never gets old: rolling your own sensors using household objects. [Nematic!] needs a way to sense vibration for an upcoming project. Instead of spending $1 plus shipping and waiting who knows how long for a spring vibration sensor to come in the mail, they made one in a matter of minutes.
A spring vibration sensor is a simple device that can be used as a poor man’s accelerometer, or simply to detect vibration. All you need is a length of conductive wire, a 10 kΩ resistor, and a way to pick up those good vibrations. For the purposes of demonstration, [Nematic!] is using an Arduino Nano in the short build video after the break.
The wire is wound around the threads of a bolt to form a coil that’s just large enough for a resistor to fit inside. One end of the coil is connected to 5 V, and one leg of the resistor connects to an input pin. Together, they form a normally-open switch. When vibrations force the free ends of both to touch, the circuit is complete and the pin is pulled high.
If you make one of these and find the sensitivity is off, just twist up a new coil with stiffer or softer wire depending on the problem. Iterating doesn’t get much cheaper than wrapping wire around a bolt. We can’t wait to see how [Nematic!] will use this sensor. In the meantime, we’re planning to use one to detect when the dryer stops running and send a text.
You may have heard about a new bill working its way through the US congress, the EARN IT act. That’s the “Eliminating Abusive and Rampant Neglect of Interactive Technologies Act of 2020”. (What does that mean? It means someone really wanted their initials to spell out “EARN IT”.)
EARN IT is a bipartisan bill that claims to be an effort to put a dent in child exploitation online. It’s also managed to catch the attention of the EFF, Schneier, and a variety of news outlets. The overwhelming opinion has been that EARN IT is a terrible idea, will make implementing end-to-end encryption impossible, and violates the First and Fourth Amendments. How does a bill intended to combat child pornography and sex trafficking end up on the EFF bad list? It’s complicated.
We’ve seen pinhole camera builds before, but this new one looks interesting. The Scura is a new open-source design for a pinhole camera that shoots on analog 35 mm film. It is all 3D printable except for a handful of screws, magnets, and the pinhole itself, which is laser cut. The cool and unusual part of the design, though, is the curved film holder, which produces 60 mm by 25 mm (2.3 in by 0.98 in) panoramic images that are sharp to the edges.
I’ve been using my Kinesis Advantage keyboard for two months, and I love it. I’ll never go back to a regular keyboard again if I can help it.
There are a few downsides to it, however. The biggest one is that split distance between the two sides is fixed. It doesn’t have Cherry MX blues (although the browns plus the firmware beeps is pretty nice). It doesn’t have layers, really — just a ten-key under the right hand. And honestly, it’s not very portable.
I took the Kinesis out to a coffee shop a few times before they all dried up into drive-thrus, and plunking it down on a four-top out in public made me realize just how large and loud it really is.
And so I’m building an ErgoDox keyboard. What I really want to build is a Dactyl — a curved variation on the ErgoDox — but I can’t just go whole-hog into that without building some type of keyboard first. That’s just my practical nature, I guess. I realize that the comparison is weak, because I’ll have to hand-wire the keyboard matrix when I make the dactyl. Assembling an ErgoDox is child’s play, comparatively. Our goal today is to lay out just what I’m getting myself into with a build like this one.
The Valve Index VR headset incorporates a number of innovations, one of which is the distinctive off-ear speakers instead of headphones or earbuds. [Emily Ridgway] of Valve shared the design and evolution of this unusual system in a deep dive into the elements of the Index headset. [Emily] explains exactly what they were trying to achieve, how they determined what was and wasn’t important to deliver good sound in a VR environment, and what they were able to accomplish.
First prototype, a proof-of-concept that validated the basic idea and benefits of off-ear audio delivery.
Early research showed that audio was extremely important to providing a person with a good sense of immersion in a VR environment, but delivering a VR-optimized audio experience involved quite a few interesting problems that were not solved with the usual solutions of headphones or earbuds. Headphones and earbuds are optimized to deliver music and entertainment sounds, and it turns out that these aren’t quite up to delivering on everything Valve determined was important in VR.
The human brain is extremely good at using subtle cues to determine whether sounds are “real” or not, and all kinds of details come into play. For example, one’s ear shape, head shape, and facial geometry all add a specific tonal signature to incoming sounds that the brain expects to encounter. It not only helps to localize sounds, but the brain uses their presence (or absence) in deciding how “real” sounds are. Using ear buds to deliver sound directly into ear canals bypasses much of this, and the brain more readily treats such sounds as “not real” or even seeming to come from within one’s head, even if the sound itself — such as footsteps behind one’s back — is physically simulated with a high degree of accuracy. This and other issues were the focus of multiple prototypes and plenty of testing. Interestingly, good audio for VR is not all about being as natural as possible. For example, low frequencies do not occur very often in nature, but good bass is critical to delivering a sense of scale and impact, and plucking emotional strings.
“Hummingbird” prototype using BMR drivers. Over twenty were made and lent to colleagues to test at home. No one wanted to give them back.
The first prototype demonstrated the value of testing a concept as early as possible, and it wasn’t anything fancy. Two small speakers mounted on a skateboard helmet validated the idea of off-ear audio delivery. It wasn’t perfect: the speakers were too heavy, too big, too sensitive to variation in placement, and had poor bass response. But the results were positive enough to warrant more work.
In the end, what ended up in the Index headset is a system that leans heavily on Balanced Mode Radiator (BMR) speaker design. Cambridge Audio has a short and sweet description of how BMR works; it can be thought of as a hybrid between a traditional pistonic speaker drivers and flat-panel speakers, and the final design was able to deliver on all the truly important parts of delivering immersive VR audio in a room-scale environment.
As anyone familiar with engineering and design knows, everything is a tradeoff, and that fact is probably most apparent in cutting-edge technologies. For example, when Valve did a deep dive into field of view (FOV) in head-mounted displays, we saw just how complex balancing different features and tradeoffs could be.
High Altitude Balloons (HAB) are a great way to get all kinds of data and shoot great photos and video, but what goes up must come down. Once the equipment has landed, one must track it down. GPS and LoRA, with its long wireless range and ease of use, are invaluable tools in tracking payloads that have returned to Earth. [Dave Akerman] has made handheld receivers to guide him to payloads, but wanted something even smaller; ideally something that could be worn on the wrist.
Not only is the new firmware functional, but it’s got a wonderful user interface. GitHub repository for the new firmware is here, and you can see the UI in action in the brief video embedded below.
