Domino Ring Machine Tips Tiles In A Never-ending Wave

February 9, 2023 by Donald Papp 9 Comments

Like to see dominoes fall? [JK Brickworks] has got what you need, in the form of a never-ending ring of falling and resetting tiles. LEGO pieces are the star in this assembly, which uses a circular track and moving ramp to reset tiles after they have fallen. Timed just right, it’s like watching a kinetic sculpture harmoniously generating a soliton wave as tiles fall only to be endlessly reset in time to fall again.

A Mindstorms IR sensor monitors a tile’s state for timing.

It’s true that these chunky tiles aren’t actually dominoes — not only are they made from LEGO pieces and hinged to their bases, they have a small peg to assist with the reset mechanism. [JK Brickworks] acknowledges that this does stretch the definition of “dominos”, but if you’re willing to look past that, it’s sure fun to see the whole assembly in action.

The central hub in particular is a thing of beauty. For speed control, an IR sensor monitors a single domino’s up/down state and a LEGO Mindstorms EV3 with two large motors takes care of automation.

The video does a great job of showing the whole design process, especially the refinements and tweaks, that demonstrate the truly fun part of prototyping. [JK Brickworks] suggests turning on subtitles for some added details and technical commentary, but if you’re in a hurry skip directly to 4:55 to see it in action.

Want to see more automated domino action? This domino-laying robot sets them up for you to knock down at your leisure, and this entirely different robot lays out big (and we do mean BIG) domino art displays.

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With ChatGPT, Game NPCs Get A Lot More Interesting

February 8, 2023 by Donald Papp 24 Comments

Not only is AI-driven natural language processing a thing now, but you can even select from a number of different offerings, each optimized for different tasks. It took very little time for [Bloc] to mod a computer game to allow the player to converse naturally with non-player characters (NPCs) by hooking it into ChatGPT, a large language model AI optimized for conversational communication.

If you can look past the painfully-long loading times, even buying grain (7:36) gains a new layer of interactivity.

[Bloc] modified the game Mount & Blade II: Bannerlord to reject traditional dialogue trees and instead accept free-form text inputs, using ChatGPT on the back end to create more natural dialogue interactions with NPCs. This is a refinement of an earlier mod [Bloc] made and shared, so what you see in the video below is quite a bit more than a proof of concept. The NPCs communicate as though they are aware of surrounding events and conditions in the game world, are generally less forthcoming when talking to strangers, and the new system can interact with game mechanics and elements such as money, quests, and hirelings.

Starting around 1:08 into the video, [Bloc] talks to a peasant about some bandits harassing the community, and from there demonstrates hiring some locals and haggling over prices before heading out to deal with the bandits.

The downside is that ChatGPT is currently amazingly popular. As a result, [Bloc]’s mod is stuck using an overloaded service which means some painfully-long load times between each exchange. But if you can look past that, it’s a pretty fascinating demonstration of what’s possible by gluing two systems together with a mod and some clever coding.

Take a few minutes to check out the video, embedded below. And if you’re more of a tabletop gamer? Let us remind you that it might be fun to try replacing your DM with ChatGPT.

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Researchers Find “Inert” Components In Batteries Lead To Cell Self-Discharge

February 6, 2023 by Donald Papp 11 Comments

When it comes to portable power, lithium-ion batteries are where it’s at. Unsurprisingly, there’s a lot of work being done to better understand how to maximize battery life and usable capacity.

Red electrolytic solution, which should normally be clear.

While engaged in such work, [Dr. Michael Metzger] and his colleagues at Dalhousie University opened up a number of lithium-ion cells that had been subjected to a variety of temperatures and found something surprising: the electrolytic solution within was a bright red when it was expected to be clear.

It turns out that PET — commonly used as an inert polymer in cell assembly — releases a molecule that leads to self-discharge of the cells when it breaks down, and this molecule was responsible for the color change. The molecule is called a redox shuttle, because it travels back and forth between the cathode and the anode. This is how an electrochemical cell works, but the problem is this happens all the time, even when the battery isn’t connected to anything, causing self-discharge.

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Behold A Microscope That Sees By Squashing Things Into It

February 5, 2023 by Donald Papp 18 Comments

“Look with your eyes, not your hands” is something many of us have heard while growing up, but that doesn’t apply to the touch-sensitive microscope [Steve Mould] got to play with.

Gel pad removed, exposing lens and multi-directional lighting.

The wand-like device is made by Gelsight, and instead of an optical lens like a normal microscope, it sports a gel pad on the sensing end. By squashing an object into the gel, the device is able to carefully illuminate and image the impression created. By taking multiple images lit from different angles, a lot of information can be extracted.

The result is a high-resolution magnification — albeit a monochromatic one — that conveys depth extremely well. It’s pretty neat clearly seeing tiny specks of dust or lint present on surfaces when [Steve] demonstrates imaging things like coin cells.

Many a hacker knows that the devil is in the details when it comes to executing an idea. Even so, the basic principles of the Gelsight seem simple enough and possibly within the realm of inspired DIY in the same way that we saw a CNC gantry and USB microscope repurposed as an optical comparator.

Watch the Gelsight in action in the video below, embedded below the page break.

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Dishwasher Repair Nightmare: Chasing Down 3 Faults

February 5, 2023 by Donald Papp 42 Comments

It all started with a vague error code (shown in the image above) on [nophead]’s Bosch SMS88TW01G/01 dishwasher, and it touched off a months-long repair nightmare that even involved a logic analyzer. [nophead] is normally able to handily diagnose and repair electronic appliances, but this time he had no idea what he was in for.

Not many dishwashers require breaking out a logic analyzer and 3D-printed custom adapters, but this one did.

Not only were three separate and unrelated faults at play (one of them misrepresented as a communications error that caused a lot of head-scratching) but to top it all off, the machine is just not very repair-friendly. The Bosch device utilized components which are not easily accessible. In the end [nophead] prevailed, but it truly was a nightmare repair of the highest order. So what went wrong?

One error appears to have been due to a manufacturing problem. While reverse-engineering the electronics in the appliance, [nophead] noticed a surface-mounted transistor that looked crooked. It was loose to the touch and fell into pieces when he attempted to desolder it. This part was responsible for switching an optical sensor, so that was one problem solved.

Another issue was a “communications error”. This actually came down to ground leakage due to a corroded and faulty heater, and to say that it was a pain to access is an understatement. Accessing this part requires the machine to be turned upside down, because the only way to get to it is by removing the base of the dishwasher, which itself requires a bizarre series of awkward and unintuitive steps to remove. Oh, and prior to turning the machine upside down, one has to purge the sump pump, which required a 3D-printed adapter… and the list goes on.

And the E02 error code, the thing that started it all? This was solved early in troubleshooting by changing a resistor value by a tiny amount. [nophead] is perfectly aware that this fix makes no sense, but perhaps it was in fact related to the ground leakage problem caused by the corroded heater. It may return to haunt the future, but in the meantime, the machine seems happy.

It goes to show that even though every fault has a cause and a reason, sometimes they are far from clear or accessible, and the road to repair is just a long slog. Heck, even phones these days can be bricked by accidentally swapping a 1.3 mm screw for a 1.2 mm screw.

3 Ways To DIY Custom CNC Dust Covers

February 4, 2023 by Donald Papp 7 Comments

Home shop machinists know dust shields are important for keeping swarf out of expensive linear rails and ball screws. [Petteri Aimonen] demonstrates three inexpensive ways to DIY some bellows-style dust covers. Such things can of course be purchased, but they’re priced at a premium and not always available in the size one needs.

A bellows-style dust cover ideally maximizes extension length while minimizing side wall distortion. It should hold its shape without external support.

The first method is to fold a suitable flat plastic or paper sheet into a bellows pattern. This method is all about the fold pattern, and thankfully, there’s no need to reinvent the wheel. [Petteri] used a fellow enthusiast’s bellows folding pattern generator which is, believe it or not, itself inspired by a remarkably comprehensive US Patent Number 6,054,194.

The downside to this method is the thickness of the bellows when it is fully collapsed. The corners always contain the most material, because it is there that the material is folded upon itself, and this limits how close to the end of travel the CNC carriage can move with the bellows attached.

The second method is to cut a large number of C-shaped sections from fabric and sew them together to make bellows. This method collapses down well and holds its shape well, but the cutting and sewing it requires can be a barrier.

The final method — and the one [Petteri] found most useful — was to hack some IKEA window blinds. IKEA Schottis pleated blinds are inexpensive, with a slick finish on one side and polyester fabric. The polyester is perfect for gluing. By cutting the material at a 45-degree angle into three sections and gluing them into a U-shape, one can create a serviceable bellows-style cover for a minimum of work.

Any of the explored methods can do the job, but [Petteri] has formulas to determine the maximum extensions and folded thicknesses of each method just in case one would like to see for themselves before choosing. And if a bellows-style cover isn’t your cup of tea, check out this method for turning a plastic strip into a spring-like tube that does the same job.

Self-Watering Planters Reuse Household Jars

January 29, 2023 by Donald Papp 9 Comments

Self-watering planters are low-maintenance, and common DIY projects. What we like most about [Tommy]’s design is that it reuses empty jars to create self-watering planters. After all, jars are fantastic at reliably holding water, so why not put them to work? Incorporating jars as part of the design means fewer worries about leakage, but it also means less 3D printing is needed overall.

A wick (in this case, a piece of string) takes care of moving water from jar to the soil.

[Tommy]’s planter screws onto the threads of a jar’s neck. Getting water to the plant is helped by a small piece of string, which acts as a wick between the soil at the top and the water in the jar at the bottom. This design works best with small plants, but on the plus side there are no moving parts or other complexities. Got a 3D printer? Models for the planter are available here.

The biggest challenge for this design is that not all jar threads are alike, so planters made in this way are not completely interchangeable across all different types of jars. Fortunately, [Tommy] provides the OpenSCAD code he used to generate his design, which he created with the help of an industry guide on how to measure the finish (or threads) of jars and lids.

If you find yourself needing to further customize your own version to fit a particular container’s threads, there’s no need to start from scratch. Unsurprisingly, threads and lids are highly standardized so chances are there exists a calculator, tool, or existing model for exactly what you need.