Mesmerizing Mechanical Seven-Segment Display

October 25, 2021 by Adam Zeloof 14 Comments

Seven-segment displays are ubiquitous. From where I’m writing this, I can see several without even having to swivel my chair. We’re all familiar with their classic visage; slightly italicized numbers that are brought to life by LEDs. There are a boatload of variants available– you can get displays with a decimal point, ones with multiple numbers, and even versions in just about any color you desire, but at the core they’re all basically the same thing- an array of LEDs sitting behind a faceplate. Except for those ones that have some gears inside.

Wait, what?

You read that right– a seven-segment display that contains gears, along with a handful of cams for good measure. Artist [Kango Suzuki] created this stunning all-mechanical seven-segment display that sequentially counts up from zero to nine when a thumbwheel is spun. All of the components are cut from wood and mesh together beautifully, complete with a satisfying click when the display rolls into a new digit, which you can hear in the video at the above link. You may recognize [Kango]’s style from this incredible mechanical clock he made a few years back. Unlike his earlier work, the seven-segment display is tiny, relatively speaking. Maybe we’ll see it integrated into a larger project some day, like a mechanical-digital clock.

We just love when somebody uses intricate mechanisms to artfully emulate some piece of existing tech. This isn’t even the first time we’ve seen a mechanical seven-segment display; [Peter Lehnér] built one back in 2019, and judging by [Kango]’s twitter feed, it appears to have inspired his design. There have even been a few other 3D printed ones over the years, but as far as we know this is the first wooden one– and, in true [Kango] fashion, its beautiful.

Thanks to [J. Peterson] for the tip!

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Omni-Wheeled Cane Steers The Visually-Impaired Away From Obstacles

October 24, 2021 by Kristina Panos 21 Comments

Sure, there are smart canes out there, commercial and otherwise. We’ve seen more than a few over the years. But a group of students at Stanford University have managed to bring something novel to the augmented cane.

Theirs features a motorized omni wheel that sweeps smoothly from left to right during normal cane operation, and when the cane senses an object that turns out to be an obstacle, the omni wheel goes into active mode, pulling the user out of the path of danger.

Tied for best part of this build is the fact that they made the project with open hardware and published all the gory details in a repo, so anyone can replicate it for about $400.

The cane uses a Raspi 4 with camera to detect objects, and a 2-D LIDAR to measure the distance to those objects. There’s a GPS and a 9-DOF IMU to find the position and orientation of the user. Their paper is open, too, and it comes with a BOM and build instructions. Be sure to check it out in action after the break.

There’s more than one way to guide people around with haptic feedback. Here’s the smartest pair of shoes we’ve seen lately.

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NE-2 neon lamp illuminated side-by-side with non-illuminated

The Humble NE-2 Neon Lamp Has A New Trick

October 24, 2021 by Dave Rowntree 45 Comments

Ah, the humble neon lamp. The familiar warm orange glow has graced the decks of many a DIY timepiece, sometimes in a purely indicating duty, and sometimes forming a memory element in place of a more conventional semiconductor device. Capable of many other tricks such as the ability to protect RF circuits from HV transients, its negative resistance operating region after it illuminates gives us usable hysteresis which can used to form a switching element and the way the pair of electrodes are arranged give it the ability to indicate whether a voltage source is AC or DC. Now, due to some recent research by [Johan Carlsson] and the team at Princeton University, the humble NE-2 tube has a new trick up its sleeve: acoustic transduction.

The idea is not new at all, with some previous attempts at using electric discharge in a gas to detect audio, going back to the early part of last century, but those attempts either used atmospheric pressure air or other non-sealed devices that exhibited quite a lot of electrical noise as well as producing noxious gases. Not ideal.

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Hackaday Links: October 24, 2021

October 24, 2021 by Kristina Panos 13 Comments

It seems that the engineers of NASA’s Lucy spacecraft have some ‘splaining to do. The $981M asteroid-seeking mission launched without a hitch, but when the two solar panels unfolded, one of them failed to latch into place. Lucy’s two large solar arrays combine to an impressive 51 square meters. Both are critical to this 12-year mission as it will travel farther from the Sun than any previous spacecraft, and be gone for longer. The problem is that Lucy is on an escape route, and so they can’t just sidle up to her with a repair craft. Even so, NASA and Lockheed are “pretty optimistic” that they can fix the problem somehow. On the bright side, both solar arrays are providing power and charging batteries inside the cockpit.

It’s kind of hard to believe, but KDE is turning 25 this year! Well, the actual anniversary date (October 14th) has already passed, but the festivities continue through the 25th when KDE founder Matthias Ettrich delivers a fireside chat at 17:00 UTC. Registration begins here.

EnergyStar, purveyors of appliance efficiency ratings and big yellow stickers, will no longer recommend gas-powered water heaters, furnaces, and clothes dryers on their yearly Most Efficient list. They will continue to give them ratings, however. This move was prompted by several environmentalist groups who pointed out that continuing to recommend gas appliances would not put America on track to reach Biden’s 2050 net-zero carbon emissions goal, since they produce greenhouse gases. We totally understand the shift away from gas, but not so much the nitty gritty of this move, which the article presents as exclusive of any appliance that doesn’t run on 100% clean energy. You can’t prove that a user’s electricity is renewable. For example, this consumer is well aware that the energy company in her town still burns coal for the most part. Anyway, here’s the memo. And a PDF warning.

Sure, you can trawl eBay for space rocks, but how do you know for sure that you’re getting a real meteorite? You could play the 1 in 100 billion or so odds that one will just fall in your lap. Just a few weeks ago, a meteorite crashed through a British Columbia woman’s ceiling and landed between two decorative pillows on her bed, narrowly missing her sleeping head. Ruth Hamilton awoke to the sound of an explosion, unaware of what happened until she saw the drywall dust on her face and looked back at the bed. The 2.8 pound rock was the size of a large man’s fist and was one of two meteorites to hit Golden, BC that evening. The other one landed safely in a field.

Hackaday alum Jeremy Cook wrote in to give us a heads up that his newest build, the JC Pro Macro 2, is currently available through Kickstarter. It’s exactly what it sounds like — a Pro Micro-powered macro pad. But this version is packed with extra keyswitches, blinkenlights, and most importantly for the Hackaday universe, broken out GPIO pins. Do what you will with the eight switches, rotary encoder, and optional OLED screen, and do it with Arduino or QMK. Jeremy is offering a variety of reward levels, from bare boards with SMT LEDs soldered on to complete kits, or fully assembled and ready to go.

Is A Diode A Switch?

October 24, 2021 by Dave Rowntree 41 Comments

Many hardware people around these parts will be familiar with devices used as switches, using at least three-terminals to effect this, an input, an output and a gate. Typical devices that spring to mind are bipolar transistors, triacs and and ye olde triode valve. Can you use a diode to switch a signal even if it has only two terminals? Of course you can, and it’s a tried and trusted technique very common in test equipment and circuits that handle RF signals. (Video, embedded below.)

The trick is that diodes block current in one direction but allow it to flow in the other, denoted by the deliberately obvious symbol. So your DC signals can’t swim upstream, but the same isn’t true for AC. Signals can be passed “the wrong way” through a diode by inducing small fluctuations in the current. Put another way, if you bias the diode into conduction, changes in the downstream voltage level result in changes in the current flowing through the diode, and the (smaller) AC signal gets through. But if you take away the bias, by turning off the DC bias voltage source, the diode switches back to non-conducting, blocking the signal. And that makes a diode a DC controlled switch for AC signals.

While [IMSAI Guy] demonstrates this with a signal diode, as he explains, one would typically use a PIN diode, which has an extra intrinsic (undoped) region between the P and the N, allowing the device to fully turn off, reducing leakage significantly.

Of course, we’ve covered diodes many times from different angles, there is always something to learn. Checkout how high voltage diodes are constructed, diodes detecting ionising radiation, and finally this great series about our new favourite two-terminal device.

See, the humble diode can be fun after all!

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Tricky Screw Heads Have Disappearing Slots

October 24, 2021 by Ryan Flowers 51 Comments

Perhaps you’ve seen them, demonstrations of a machined piece of metal that upon further inspection is actually two pieces machined so perfectly that they appear as one. With extremely tight tolerances, it’s not possible to determine where one piece of metal ends and another begins — that is, until the secret is revealed. Inspired by such pieces of art, [Andrew Klein] sought to put this high level of machine work to practical use. And so it was that his as-yet-unnamed Screw With No Slot came to be.

Klein Hidden Bolt depressed by brass rod — A brass rod pushes down to reveal the keyed center section.

The screw’s disc-like appearance looks as if it’s a metal trim piece to cover a bolt hole. But in the video below [Andrew] shows us the trick, pushing a brass rod into the middle of the disc to reveal the hidden three-point slot. The center of the disk is actually a separate bit of finely machined metal that is spring loaded to stay flush. A specially designed wrench keys into the rounded concave triangle shape cut into the face.

The wrench is made with brass to avoid marring the precision surface. It uses three magnets to hold tight to the screw’s 410 magnetic stainless steel. [Andrew] didn’t spill the beans on how this was done, but we haven’t seen any process other than electrical discharge machining (EDM) that can achieve this level of mating precision. If that topic is new to you, we recommend checking out [Ben Krasnow’s] lab experiments on the topic.

We can’t help but be taken in by the beauty of the fastener, and it immediately sent our imaginations into a National Treasure induced dream-like state. [Andrew Klein] has yet to name this fastener, and he’s soliciting ideas for names in the video below the break. If you have such an idea, you can comment on his video. He’s also exploring the viability of the as-yet-named fastener as a commercial product for high end furniture builders.

This is not the first time we’ve featured [Andrew Klein]’s work. His previous featured projects include a custom sawblade for perfectly foldable joints and an unveiling of the magnetic magic behind switchable permanent magnets. Be sure to submit the neat hacks, builds, and inspiring projects that you come across to our Tip Line!

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A sandbox for ergonomic keyboard makers.

Dactyl Chimera Leaves The Learning Out Of The Curve

October 24, 2021 by Kristina Panos 11 Comments

Have you been wanting to build your own keyboard, ergonomic or otherwise, but are hesitant to spend all that time and filament on something that may not be a good fit for your hands? Glad as we are that the dactyl is open-source, to get in there and really mess around with it requires intimate knowledge of either OpenSCAD or Clojure.

Well, not anymore. [WolfIcefang]’s dactyl chimera is an ergo sandbox, a test bench for column curvature, stagger, and height that should keep you from having to iterate all day and night. It was designed in FreeCAD and has three parts — the rack, the tenting foot, and the arches. The rack acts like a bottom plate and has slots for holding the columns (arches) in place. Underneath that is the tenting foot, which changes the lateral inclination. Thirdly are the arches, the business part where the switches go.

[WolfIcefang] says it’s sturdy but not portable, and for some reason feels the need to apologize for the looks. We think it’s beautiful, but then again are easily captivated by such practicality. It’s not quite a keyboard yet, as [WolfIcefang] has neither wired it up nor burned in any firmware. This is still in the early stages, and [WolfIcefang] wants to open it up to collaborators. Plans for the future include interchangeable thumb clusters and a complete build guide.

Even if you aren’t that fluent in OpenSCAD, you’ll have fun messing around on the keycap modeling playground.

Via r/ErgoMechKeyboards