Liquid (Reversibly) Solidifies At Room Temperature, Gets Used For 3D Prints

August 9, 2024 by Donald Papp 8 Comments

Researchers demonstrate sustainable 3D printing by using poly(N-isopropylacrylamide) solutions (PNIPAM), which speedily and reliably turn solid by undergoing a rapid phase change when in a salt solution.

This property has been used to 3D print objects by using a syringe tip as if it were a nozzle in a filament-based printer. As long as the liquid is being printed into contact with a salt solution, the result is a polymer that solidifies upon leaving the syringe.

What’s also interesting is that the process by which the PNIPAM-based solutions solidify is entirely reversible. Researchers demonstrate printing, breaking down, then re-printing, which is an awfully neat trick. Finally, by mixing different additives in with PNIPAM, one can obtain different properties in the final product. For example, researchers demonstrate making conductive prints by adding carbon nanotubes.

While we’ve seen the concept of printing with liquids by extruding them into a gel bath or similar approach, we haven’t seen a process that prides itself on being so reversible before. The research paper with all the details is available here, so check it out for all the details.

Forget Ship In A Bottle, How About Joule Thief In A Fuse Tube?

August 7, 2024 by Donald Papp 14 Comments

We love close-up pictures of intricate work, and [w] hits the spot with a tiny joule thief in a fuse case (social media post, embedded below) powered by an old coin cell from a watch. It’s so tiny!

Ethernet transformers contain tiny coils.

A joule thief is a sort of minimum-component voltage booster that can suck nearly every last drop of energy from even seemingly-drained batteries, and is probably most famously used to light LEDs from cells that are considered “dead”.

Many joule thief designs feature hand-wound coils, which is great for junk box builds but certainly becomes more of a challenge for a tiny build like this one.

We really like that [w] salvaged a miniscule coil from an Ethernet transformer, most of which look like blocky SMD components from the outside but actually contain tiny coils.

The joule thief has been the basis of plenty of hacks over the years, and it’s always nice to see new twists on the concept.

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Proof That find + mkdir Are Turing-Complete

August 5, 2024 by Donald Papp 10 Comments

Data manipulation is at the heart of computation, and a system is said to be Turing-complete if it can be configured to manipulate data in a way that makes implementing arbitrary computation possible. [Keigo Oka] shared a proof that find and mkdir together are Turing-complete, which is to say, a system with only GNU’s find and mkdir has access to enough functionality to satisfy the requirements of Turing completeness, which ignores questions of efficiency or speed.

[Keigo Oka]’s first attempt at a proof worked to implement Rule 110, an elementary cellular automata configuration that has been shown to be Turing-complete, or ‘universal’, but has been updated to implement a tag system as it’s proof, and you can see it in action for yourself.

Seeing basic utilities leveraged in such a way illustrates how computation is all around us, and not always in expected places. We’ve also seen Turing-complete origami and computation in cellular automata.

The Ultimate Seed Vault Backup? How About The Moon

August 4, 2024 by Donald Papp 44 Comments

A safe haven to preserve samples of biodiversity from climate change, habitat loss, natural disaster, and other threats is recognized as a worthwhile endeavor. Everyone knows good backup practice involves a copy of critical elements at a remote location, leading some to ask: why not the moon?

Not even the Svalbard global seed vault is out of the reach of climate change’s effects.

A biological sample repository already exists in the form of the Svalbard global seed vault, located in a mountain on a remote island in the Arctic circle. Even so, not even Svalbard is out of the reach of our changing Earth. In 2017, soaring temperatures in the Arctic melted permafrost in a way no one imagined would be possible, and water infiltrated the facility. Fortunately the flooding was handled by personnel and no damage was done to the vault’s contents, but it was a wake-up call.

An off-site backup that requires no staffing could provide some much-needed redundancy. Deep craters near the moon’s polar regions offer stable and ultra-cold locations that are never exposed to sunlight, and could offer staffing-free repositories if done right. The lunar biorepository proposal has the details, and is thought-provoking, at least.

The moon’s lack of an atmosphere is inconvenient for life, but otherwise pretty attractive for some applications. A backup seed vault is one, and putting a giant telescope in a lunar crater is another.

Apollo Computer: The Forgotten Workstations

August 4, 2024 by Donald Papp 28 Comments

Ever heard of Apollo Computer, Inc.? They were one of the first graphical workstation vendors in the 1980s, and at the time were competitors to Sun Microsystems.

But that’s enough dry historical context. Feast your eyes on this full-color, 26-page product brochure straight from 1988 for the Series 10000 “Personal Supercomputer” featuring multiple processors and more! It’s loaded with information about their hardware and design architecture, giving a unique glimpse into just how Apollo was positioning their offerings, and the markets they were targeting with their products.

Apollo produced their own hardware and software, which meant much of it was proprietary. Whatever happened to Apollo? They were acquired by Hewlett-Packard in 1989 and eventually shuttered over the following decade or so. Find yourself intrigued? [Jim Rees] of The Apollo Archive should be your next stop for everything Apollo-oriented.

Vintage computing has a real charm of its own, but no hardware lasts forever. Who knows? Perhaps we might someday see an Apollo workstation brought to life in VR, like we have with the Commodore 64 or the BBC Micro (which even went so far as to sample the sound of authentic keystrokes. Now that’s dedication.)

2024 Tiny Games Contest: Pi-O-Scope-Pong

August 1, 2024 by Donald Papp 3 Comments

[Aaron Lager]’s Pi-O-Scope-Pong project takes a minimal approach to Pong by drawing on an oscilloscope to generate crisp paddles and ball. A Raspberry Pi takes care of the grunt work of signal generation, and even uses the two joysticks of an Xbox controller (connected to the Pi over Bluetooth) for inputs.

Originally, [Aaron] attempted to generate the necessary signals directly from the Pi’s PWM outputs by doing a little bit of RC filtering on the outputs, but was repulsed by the smeary results. The solution? An old but perfectly serviceable 8-bit MAX506 DAC now handles crisping up the visuals with high-quality analog outputs. Code is available on the project’s GitHub repository.

There isn’t any score-keeping or sound, but one thing that it has over the original Pong is a round ball. The ball in the original Pong game was square, but mainly because cost was a concern during design and generating a round ball would have ballooned the part count.

In many ways, Pong itself is a great inspiration for the Tiny Games Challenge, because the simplicity of its gameplay was likely a big part of its success.

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Secret Messages On Plastic, Just Add Tesla Coil

August 1, 2024 by Donald Papp 15 Comments

Here’s a short research paper from 2013 that explains how to create “hydroglyphics”, or writing with selecting surface wetting. In it, an apparently normal-looking petri dish is treated so as to reveal a message when wetted with water vapor. The contrast between hydrophobic and hydrophilic surfaces, which is not visible to the naked eye, becomes visible when misted with water. All it took was a mask, and a little treatment with a modified Tesla coil.

Plastics tend to be hydrophobic, meaning their surface repels water. These plastics also tend to be non-receptive to things like inks and adhesives. However, there is an industrial process called corona treatment (invented by Verner Eisby in 1951) that changes the surface energy of materials like plastics, rendering them more receptive to inks, coatings, and adhesives. Eisby’s company Vetaphone still exists today, and has a page describing the process.

What’s this got to do with the petri dishes and their secret messages? The process is essentially the same. By using a Tesla coil modified with a metal wire mesh, the surface of the petri dish is exposed to the coil’s discharge, altering its surface energy and rendering it hydrophilic. By selectively blocking the discharge with a nonconductive mask made from a foam sticker, the masked area remains hydrophobic. Mist the surface with water, and the design becomes visible.

The effects of corona treatment decay over time, but we think this is exactly the sort of thing that is worth keeping in mind just in case it ever comes in useful. Compact Tesla coils are fairly easy to get a hold of nowadays, but it’s also possible to make your own.