# Logic Flows, Literally, In This Water Adder

A lot of elementary electronic texts use water as an analogy for electricity. You know, pressure is voltage, flow is current, and pipe diameter is resistance. It is ironic, then, that some people use fluids to build logic gates and, in fact, you can make any logic circuit you like using nothing but water flowing through some structures. Don’t think so? Have a look at the video from [Steve Mould] below.

Fluidic logic isn’t anything new, but it has always been a bit exotic. Usually, replacing electrons with water or even air — which is a kind of fluid — means you are trying to operate in a tough environment or have some other special need. As far as we can tell, [Steve] did it just because he could, and we get that.

# Retrotechtacular: Renewable Energy, 1948 Edition

If you’ve got 10 minutes, how about a quick break to watch a video about renewable clean electric power? Must be a recent video, right? Nope. The Coronet Instruction Film below is from 1948 and covers using rivers to generate power. Hydropower isn’t a new idea, of course, and the film starts out with an old-fashioned water wheel. That’s not really what they are driving at, though.

The announcer sounds just like the guy who narrated all the film strips you saw in school. There are some good vintage shots of Niagra Falls and some other dams. The video also makes some economic arguments about hydroelectric versus coal and why some rivers aren’t suitable for power generation.

# Where We’re Going, We Don’t Need Keycaps

Just when we thought we’d seen the peak of ergonomic, split keyboards, along comes [Peter Lyons] with the Squeezebox — an adjustable, column-staggered, streamlined beauty with 21 keys per hand. Much like the Kinesis Advantage and the Dactyl, the user’s fingers are allowed to dangle comfortably and stay in their naturally curled position, moving as little as possible between keys, rows, and columns. But the Squeezebox goes a few steps farther to reduce finger travel.

For starters, each column of keys is adjustable on the fly in the Y-direction by loosening the screw and sliding it until it’s just right. The columns are also adjustable in the Z-direction, but for now, this requires reprinting a few parts. In case you didn’t notice, the grid is pretty tightly packed, and those low-profile Kailh choc switches are naked to the world, mostly because keycaps wouldn’t fit anyway.

At that angle, there’s no reaching required at all between the middle and bottom rows. The 100° corner that they form both invites and supports chording — that’s pressing multiple keys simultaneously to do some action. There’s no real need to reach for the top row, either, because [Peter] merely moves his finger upward in the Z-direction a little bit to hit those. The similarly-angled thumb clusters are chord-able as well, and their position relative to the mainland is adjustable thanks to a grid of holes that are meant for threaded inserts. Genius!

For the next version, [Peter] plans to bring the three sets of thumb cluster switches closer together, and arrange them like a tri-fold science fair display board. Be sure to check out the super cool but somewhat impossible-to-solder prototypes in the build log, and stay for more stuff in the huge build gallery. Typing demo is after the break.

Still too much travel for your taste? How about a 5-way for each finger?

# Pneumatic Can Crusher Awaits Your Command

A powerful robot awaiting for a verbal command to crush its foes might sound like something from a science fiction film, but now it’s a permanent fixture of the [Making Stuff] garage.  (Video, embedded below.) Thankfully this robot’s sworn enemy are aluminum cans, and the person controlling it with their voice isn’t a maniacal scientist, just a guy who’s serious about recycling. Well, we hope so anyway.

The star of the show is a heavy duty wall-mounted can crusher that [Making Stuff] built from some scrap steel and a pneumatic cylinder hooked up to the garage’s compressed air system. A solenoid operated valve allows an Arduino with attached ESP-01 to extend the cylinder whenever the appropriate command comes over the network. In this case, the goal was to tie the crusher into Google Assistant so a can would get smallified whenever one of Google’s listening devices heard the trigger phrase.

Obviously, those who’d rather keep Big Data out of their recycling bin don’t have to go down the same path. But that being said, having to give a specific voice command to activate the machine does provide a certain level of operational safety. At least compared to trusting some eBay sensor to tell the difference between an aluminum can and a fleshy appendage.

After crushing a few cans with his new toy, [Making Stuff] noticed a fairly troubling flaw in the design. Each time a can was crushed he had to reach into the maw of the machine to push its little flattened carcass out of the way. In other words, he was one bad line of code away from having one good hand.

The solution ended up being a new hose that runs from the exhaust port of the valve to the crushing chamber: once the cylinder retracts, the air exiting the valve pushes the crushed can out the rear of the machine and into a waiting pail underneath. Very slick.

Even if you’re not interested in the voice control aspect, this is a great design to base your own can crusher on. While it’s always a treat when a fully automatic crusher comes our way, we’ll admit the challenges of getting one to work reliably probably aren’t worth the hassle.

# Indian Makers Respond To The COVID-19 Pandemic By Producing Oxygen Concentrators

We’ve all spent the last year or more under the shadow of the COVID-19 pandemic, and though some of us may have been vaccinated or come through its various waves it remains far from over. One of the hardest-hit parts of the world at the moment is in India, where health services are struggling to maintain adequate oxygen supply such is the demand for it from sick patients.

India’s hacker and maker community have risen to the challenge and done their bit to supply needed resources, and fresh from last year’s PPE manufacturing efforts a group from the Makers Asylum hackerspace in Goa have launched upon a fresh challenge. They aim to start producing the established open-source OxiKit oxygen concentrator in the Indian hackerspace community using locally manufactured parts, and they’ve launched a crowdfunding effort to cover their development, prototyping, and certification work.

The oxygen concentrator project builds on Makers Asylum’s experience last year as part of an extremely successful network of makerspaces producing PPE, which demonstrates that they have the resources, logistics, and ability to take on a project of this size. The OxiKit is no hare-brained contraption but an established and successful design that is already at work, so we believe that this project has a good chance of success. It’s close to home for Hackaday too, and one of the people involved with it is our colleague [Anool Mahidharia].

In a global pandemic only a global response can overcome the incredible challenges before us. For that reason we’d like to urge you to take a look at the Makers Asylum page wherever you are, and if you can, support it.

# Linux Fu: A Little Bit Of (Network) History Repeating Itself

These days, embedded systems often have networks and that can make them significantly more complex. Networks are usually pretty nondeterministic and there are a variety of oddball conditions. For example, when your public-access pick and place machine gets written up on Hackaday and you suddenly get a 50X surge in traffic, how does your network stack handle it? While there’s no silver bullet for network testing, there are some tricks that can make it easier and one of those is the `tcpreplay` utilities that allow you to record complex network traffic and then play it back in a variety of ways. This has many benefits, especially if you manage to capture that one thing that triggers bad behavior sporadically. Being able to play it back on demand can speed up diagnostics considerably.

## General Idea

You probably know that `tcpdump` allows you to grab packet captures from a network interface and save them to a file. If you prefer a GUI, you probably use Wireshark, which uses the same underlying library (`libpcap`) to grab the data. In fact, you can capture data using `tcpdump` and look at it with Wireshark, although there are other tools like `tcptrace` or `Ngrep` that can work with the output, also.

While the output of the command can be a little cryptic without tool support, a program called `tcpreplay` can take that data and feed it back in a variety of ways. Of course, you can modify the file first — there are tools to make that easier and — if you need to — you can craft your own network traffic by hand or using one of a variety of tools. This process is often called “packet crafting.”

# Disney Imagineering’s “Project Kiwi” Bears Groot

Some days, we might be forgiven for believing Boston Dynamics has cornered the market on walking robots. They (and other players) are making incredible progress in their field, but three years ago Disney, trying to create autonomous, free-walking robotic actors for some of their more diminutive film characters, found none of the existing platforms were appropriate. So they set their Imagineering department to work on “Project Kiwi”, and we are now seeing the fruits of those efforts.

Research on bipedal robots has amassed over the years, and as the saying goes, if these Imagineers saw further it was by standing on the shoulders of larger robotic platforms. However, the Project Kiwi designers have made a laundry list of innovations in their process of miniaturization, from the “marrow conduit” cooling system which forces air through hollow bones, to gearing that allows actuators to share motors even across joints. The electronics are distributed around the skeleton on individual PCBs with ribbon flex cables to reduce wiring, and almost every component is custom fabricated to meet the complex size and weight requirements.

Even in this early prototype, Disney’s roots in life-like animatronics are evident. Groot’s movements are emotive, if a bit careful, and software can express a variety of personalities through his gaits and postures. The eyes and face are as expressive as we’ve come to expect (though a keen eye for seams puts off some definite Westworld vibes). Reportedly, this version can handle gentle shoves and contact, but we do spot a safety cable still attached to the head. So there’s probably some way to go before we’ll see this interacting with the general public in a park.

Disney’s Imagineering department has been doing some amazing work with robotics and they continue to make significant innovations in the more traditional fields of animatronics. It certainly looks like one of the coolest places to work right now, and now we’re itching to build our own bipedal friends to play with.