Finger Bend Is A Textile Flex Sensor You Can Sew At Home

April 2, 2021 by Lewin Day 2 Comments

So often, we use control devices for electronics that involve our fingers directly grasping, touching, or moving another object or surface. It’s less common for us to use interfaces that detect the motion of our bodies directly. Flex sensors are one way to do that, and it’s exactly what [WillpowerStudios] aims to do with Finger Bend.

The construction of the sensor is simple, using piezoresistive fabric which changes its resistance when deformed. By sewing this into a sheath that can be placed on the finger, and wiring it up with conductive threads, it can be used to detect the flexion of the wearer’s digits by sampling the resistance with an analog to digital converter on any garden variety microcontroller. Expanding the technique to a full hand is as simple as creating a Finger Bend per digit and wiring up each one to its own ADC channel. If you want to get really fancy, you could even scan through them at speed with a multiplexer.

It’s similar to the technology used in Nintendo’s infamous Power Glove, and while it’s never caught on in the mainstream, it may have applications yet. Video after the break

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Adjustable, Low-Impact Keeb Is About As Comfortable As It Gets

April 2, 2021 by Kristina Panos 19 Comments

What’s the coolest-looking way to ease the repetitive stress of typing without quitting altogether? Move nothing but your fingers, and move them as little as possible without any stretching or reaching. We’ve been fans of the weirdly wonderful DataHand keyboard since we first laid eyes on one, but [Ben Gruver] has actually been using these out-of-production keyboards for years as a daily driver. And what do we do when we love something scarce? Make our own, improved version like [Ben] has done, with the lalboard.

[Ben] has been using the lalboard for about two years now and has a laundry list of improvements for version two, a project we are proud to host over on IO. Many of the improvements are designed to make this massive undertaking a bit easier to print and put together. Version one uses copper tape traces, but [Ben] is working on a fab-able PCB that will use something other than a pair of Teensy 2.0s, and perhaps QMK firmware.

Something that won’t be changing is the fantastic optical key switch design that uses an IR LED and phototransistor to capture key presses, and tiny square magnets to return the key to the home position and deliver what we’re quite sure is a satisfying clack.

The absolute coolest part of this keyboard is that it’s so adjustable. Every key cluster can be adjusted in 6 directions, which includes the ability to dial in different heights for each finger if that’s what works best. Once that’s all figured out, then it’s time to print some perfect permanent standoffs. Want to make one of these sci-fi clackers for yourself? [Ben] has the BOM, some printing instructions and tips, and a guide to making the copper tape PCBs over on GitHub. Check it out in action after the break as [Ben] rewrites Kafka’s Metamorphosis at 120 WPM.

Interested in learning more about the original DataHand keyboard? Here’s our take.

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Flashpen Is A High Fidelity Pen Input Device

April 1, 2021 by Lewin Day 10 Comments

Pen input has never really taken off in the computing mainstream, though it’s had somewhat of a renaissance in the last decade or so. Various smartphones and tablets are shipping with the technology, and some diehard users swear by it as the best way to take notes on the go. Recently, researchers at the Sensing, Interaction and Perception Lab at ETH Zurich have been working on Flashpen, a high-fidelity pen interface for a wide range of applications.

The fundamental technology behind the pen is simple, with the device using an optical flow sensor harvested from a high-end gaming mouse. This is a device that uses an image sensor to detect the motion of the sensor itself across a surface. Working at an update rate of 8 KHz, it eclipses other devices in the market from manufacturers such as Wacom that typically operate at rates closer to 200Hz. The optical sensor is mounted to a plastic joint that allows the user to hold the pen at a natural angle while keeping the sensor parallel to the writing surface. There’s also a reflective sensor on the pen tip which allows cameras to track its position in space, for use in combination with VR technology.

The team show off the device being used in several ways, primarily in VR tasks, but also in simple handwriting and coloring work. It’s a project that could readily be replicated by any eager experimenter by gutting a gaming mouse and getting down to work; our writers will expect six of your submissions by June 1st to the tipsline. Those eager to learn more can check out the project paper, and may also find the team’s TapID technology interesting. Video after the break. Continue reading “Flashpen Is A High Fidelity Pen Input Device” →

Extinguish Squeaks 24/7 With Refillable WD-40

April 1, 2021 by Kristina Panos 43 Comments

It’s 10:34PM and you’ve just run out of water displacement formula #40. You could wait until tomorrow to get a new can, or you could spend the rest of the night turning an old, empty fire extinguisher into a refillable and re-pressurizable WD-40 dispenser like [liquidhandwash] did. The part count is pretty low, but it’s awfully specific.

And the emphasis is on empty extinguisher. Part of the deal involves twisting the gauge off, and we wouldn’t want you to get blasted in the face with any last gasps of high-powered firefighting foam. In order to make the thing re-pressurizable, [liquidhandwash] stripped all the rubber from a tire valve and removed the core temporarily so it could be soldered into the fitting where the gauge was. The handy hose is from a large can of WD-40, which is also where the label came from — since it’s no longer a fire extinguisher, it needs to stop bearing resemblance to one, so [liquidhandwash] removed the sticker, painted it blue, and glued the cut-open can to the outside.

To use it, [liquidhandwash] fills it up about halfway and then pressurizes it through the tire valve with a bike pump or compressor. (We think we’d go with bike pump.) Since [liquidhandwash] goes through so much lubricant, now, they can just buy it by the gallon and keep refilling the extinguisher.

Is WD-40 your everything hammer? Variety is the spice of shop life.

Pneumatic Actuator Made Out Of Lasercut Plastic

March 30, 2021 by Lewin Day 17 Comments

Pneumatics are a great solution for all kinds of actuators, and can even be used for logic operations if you’re so inclined. Typically, such actuators rely on nicely machined metal components with airtight rubber seals. But what if you did away with all that? [Richard Sewell] decided to investigate.

The result is a pneumatic actuator built out of lasercut acetal parts. The mechanism consists of of two outer layers of plastic acting as the enclosure, and a cut-out middle layer which creates the air chamber and houses the actuating arm itself. It’s a single-acting design, meaning the air can push the actuator one way, with a spring for return to the neutral position. The action is quite fast and snappy, too.

[Richard] aims to tweak the design further by improving the registration between the features of each layer and reduce the rubbing of the actuator’s rotor on the surrounding parts. If you’ve got the know-how, sound off in the comments. Alternatively, consider looking into soft pneumatics as well. Video after the break.

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Should Have Used A Vacuum Tube 555

March 28, 2021 by Dan Maloney 65 Comments

“You should have used a 555” has become a bit of a meme around these parts lately, and for good reason. There seems to be little that these ubiquitous chips can’t be used for, and in a world where code often substitutes for hardware, it’s easy to point to instances where one could have just used a simple timer chip instead.

Definitely not in the meme category, though, is this overkill vacuum tube 555 timer. It comes to us via [David Lovett], aka [Usagi Electric], who has lately caught the “hollow state” electronics bug and has been experimenting with all sorts of vacuum tube recreations of circuits we’re far more used to seeing rendered in silicon than glass. The urge to replicate the venerable 555 in nothing but vacuum tubes is understandable, as it uses little more than a pair of comparators and a flip-flop, circuits [David] has already built vacuum tube versions of. The only part left was the discharge transistor; a pentode was enlisted to stand in for that vital function, making the circuit complete.

To physically implement the design, [David] built a large PCB to hold the 18 vacuum tubes and the handful of resistors and capacitors needed. Mounted on eight outsized leads made from sheet steel, the circuit pays homage to the original 8-pin DIP form of the 555. The video below shows the design and build process as well as testing of all the common modes of operation for the timer chip.

You can check out more of our coverage of [David]’s vacuum tube adventures, which started with his reverse-engineering of an old IBM logic module. And while he did a great job explaining the inner workings of the 555, you might want to take a deeper dive into how the venerable chip came to be.

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Archery Release Becomes Reusable Balloon Cutdown Mechanism

March 27, 2021 by Donald Papp 11 Comments

A cutdown in high-altitude balloon (HAB) parlance refers to detaching a payload, and can refer to the act of severing a line or to the mechanism itself. How is this done? The most common way is the “hot wire” method: a segment of wire is heated rapidly with a high current, causing it to melt through something like a nylon line.

But there’s more than one way to solve a problem, and while documenting different cutdown methods, [KI4MCW] found that a caliper-style archery release plus hobby servo could be used as a high strength cutdown mechanism. An archery release (or bow release) is a tool to assist in holding the string of a bow in the drawn position, and cleanly release it at the touch of a lever or button. It occurred to [KI4MCW] that these features might be made to serve as a payload release as well, and you can see here the crude but successful prototype for a reusable cutdown.

The archery release [KI4MCW] obtained opens its jaws when a trigger-style lever on the side is pulled. The force required to trigger this is remarkably low, and a low-torque economical hobby servo easily does the job. In fact, the force needed to trip the release is so low that [KI4MCW] added a short rubber band to provide some opposing tension on the lever, just to be sure no spontaneous triggers occurred. The device hasn’t flown yet, but the prototype looks promising. Maybe a mechanism like this would be appropriate for a payload like dropping a high-altitude RC glider from a balloon.