Knowing That It Is Possible

September 6, 2025 by Elliot Williams 10 Comments

We like to think that we can do almost anything. Give me a broken piece of consumer electronics, and I’ll open it up and kick the capacitors. Give me an embedded Linux machine, and I’ll poke around for a serial port and see if it’s running uboot. But my confidence suddenly pales when you hand me a smartphone.

Now that’s not to say that I’ve never replaced a broken screen or a camera module with OEM parts. The modern smartphone is actually a miracle of modularity, with most sub-assemblies being swappable, at least in principle, and depending on your taste for applying heat to loosen up whatever glue holds the damn things together.

But actually doing hardware hacking on smartphones is still outside of my comfort zone, and that’s a shame. So I was pretty pleased to see [Marcin Plaza] attempt gutting a smartphone, repackaging it into a new form factor, and even adding a new keyboard to it. The best moment in that video for me comes around eight minutes in, when he has completely disassembled all of the modules and is laying them out on his desk to see how little he needs to make the thing work. And the answer is batteries, motherboard, USB-C, power button, and a screen. That starts to seem like a computer build, and that’s familiar turf.

That reminded me of [Scotty Allen]’s forays into cell-phone hackery that culminated in his building one completely from parts, and telling us all about it at Supercon ages ago. He told me that the turning point for him was realizing that if you have access to the tools to put it together and can get some of the impossibly small parts manufactured and/or assembled for you, that it’s just like putting a computer together.

So now I’ve seen two examples. [Scotty] put his together from parts, and [Marcin] actually got a new daughterboard made that interfaces with the USB to add a keyboard. Hardware hacking on a cellphone doesn’t sound entirely impossible. You’d probably want a cheap old used one, but the barrier to entry there isn’t that bad. You’ll probably have to buy some obscure connectors – they are tiny inside smartphones – and get some breakout boards made. But maybe it’s possible?

Anyone have more encouragement?

Spinning Top Chair Revisited

September 6, 2025 by Fenix Guthrie 11 Comments

Designer furniture generally comes with excellent aesthetics and (sometimes) functionality. However, such furniture comes with a price to match. One such piece of furniture is the Magis Spun Chair. It’s a striking piece with a fun party trick to match: it works like a top spinning while you sit inside. However, it has a prohibitively expensive price tag of $1,200 to match. That’s why [Morley Kert] is on a mission to build one for less.

This isn’t [Morley]’s first time building a spinning chair. The first attempt featured numerous 3D printed pieces glued together. It did not inspire confidence in spinning, nor was it a striking piece of furniture. So a revisit was in order.

This time around the chair’s construction was CNC milled plywood. Some surfaces featured 3D carving, but the majority were left raw with carving the final shape handled manually. Despite its size, the chair only took four and a half sheets of 3/4 inch plywood by hollowing out the base allowing for more efficient use of material. Once the router had completed the pieces, they were stacked and glued together. Each layer was aligned with hidden dowels making the assembly process fairly straightforward.

However, while usable, the chair looked rather unfinished, so [Morley] went to town on it with a power carving angle grinder. To ensure even carving on the circular profile of the chair, he placed it, or for some sections glued it, on an electronic lazy Susan. After some practice, the carving process turned out really well with a well-shaped and professional looking chair. Some wood varnish and a large amount of sanding finished up the chair very nicely for a total material cost of under $500.

We were happy to see the completion of this chair building saga. If you want to see [Morley] make even more designer furniture for cheap, make sure to check out his other 3D printed chair!

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Faux Potentiometers Use Magnets, No Contacts

September 6, 2025 by Al Williams 22 Comments

Ever tear open a potentiometer? If you haven’t, you can still probably guess what’s inside. A streak of resistive material with some kind of contact that moves across it as you rotate the shaft, right? Usually, you’d be right, but [T. K. Hareedran] writes about a different kind of pot: ones that use magnetic sensing.

Why mess with something simple? Simplicity has its price. Traditional units may not be very accurate, can be prone to temperature and contamination effects, and the contact will eventually wear out the resistive strip inside. However, we were a little curious about how a magnetic potentiometer could offer a resistive output. The answer? It doesn’t.

Really, these would be better described as rotary encoders with a voltage output. They aren’t really potentiometers. The SK22B mentioned in the article, for example, requires a 5 V input and outputs somewhere between 10% and 90% of that voltage on the ersatz wiper pin.

That makes the devices much easier to puzzle out. The linearity of a device like that is better than a real pot, and, of course, the life expectancy is greatly increased. On the other hand, we’d rather get one with quadrature or I2C output and read it digitally, but if you need a voltage, these devices are certainly an option.

[T. K.] goes on to show how he fabricated his own non-contact sensor using photosensors and a gray-coded wheel with a single track. You do need to be careful about where you position the sensors, though.

Could you make a real non-contact resistive pot? Seems like you could get close with an FET output stage, but it wouldn’t be as generally applicable as a good old-fashioned smear of carbon. If you have a better idea, drop it in the comments or build it and give us a tip.

Want a 20A-capable device? Build it. Want to see how we like to read encoders?

The Decisioninator Decides Dinner, Saves Marriage

September 5, 2025 by Tyler August 14 Comments

For something non-explosive, this might be the most American project we’ve featured in a while. [Makerinator]’s domestic bliss was apparently threatened by the question “what shall we have for dinner”– that’s probably pretty universal. Deciding that the solution was automation is probably universal to software devs and associated personalities the world over. That the project, aptly called “The Decisioninator” apes a popular game-show mechanic to randomly select a fast-food restaurant? Only people with 100-octanes of freedom running through their veins can truly appreciate its genius.

In form factor, it’s a tiny slot machine which [Makerinator] fabbed up on his laser cutter. The lovely “paintjob” was actually a print out with dye-sublimation ink that was transferred to plywood before laser cutting. Mounted to this are illuminated arcade buttons and a small ISP display. The interface is simplicity itself: the big button spins a virtual “wheel” on the display (with sound effects inspired by The Price is Right) to tell the family what deliciously unhealthy slop they’ll be consuming, while the other button changes decision modes. Of course you can pick more than just dinner with The Decisioninator. You need only decide what spinners to program. Which, uh, that might be a problem.

Luckily [Makerinator] was able to come up with a few modes without recursively creating a The Decisioninator-inator. He’s got the whole thing running on a Pi4, which, with its 1980s supercomputer performance, is hilariously overpowered for the role it plays (in true American fashion). He’s coded the whole thing in the Flame Engine, which is a game engine built on the Flutter UI toolkit by American technology giant Google.

What’s more American than tech giants and fast food? A propane powered plasma cannon, for one thing; or maybe mental gymnastics to translate into freedom units, for another.

Thanks to [Makerinator] for the tip.

A photo of two magnetic bubble memories installed in a circuit board

Scott Baker’s Magnetic Bubble Memory Mega-Post

September 5, 2025 by John Elliot V 10 Comments

Over on his blog our hacker [Scott Baker] has a Magnetic Bubble Memory Mega-Post.

If you haven’t heard of magnetic bubble memory before it’s basically obsolete nonvolatile memory. Since the 1970s when it was introduced this type of memory has been outperformed in every dimension including durability, reliability, price, density, performance, and so on. For any given application of bubble memory you will be able to find an alternative technology which is better in many ways. Except if you want some old tech to geek out over, in that case magnetic bubble memory is for you!

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Restoring A Cheap Fume Hood

September 5, 2025 by Fenix Guthrie 8 Comments

Semiconductor fabrication is complicated requiring nasty chemicals for everything from dopants to etchants. Working with such chemicals at home is dangerous and after releasing hydrochloride acid fumes into his lab, [ProjectsInFlight] decided the time was right to get one for a mere $200.

I can hear the readers down in the comments already saying, “why not just make one?” But a properly engineered fume hood provides laminar flow which absolutely ensures no leakage of fumes out of the hood. However, such proper engineering comes with an impressive price tag, so the used market was the only choice. This is less dangerous then it sounds as companies are required by both OSHA and the EPA to clean their fume hoods before removal, so no chemical residue should remain after purchase.

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Dialing It In: A 3D-Printed Knob With Touchscreen Flair

September 5, 2025 by Matt Varian 34 Comments

Knobs are ubiquitous in technology user interfaces, but touchscreens are increasingly replacing them for interface controls. The latest project from [upir] combines a rotating knob with a touchscreen for a stunning result. The knob-over-display design features a touchscreen where you can place and remove a spinning knob, creating an interface reminiscent of Microsoft’s Surface Dial but at a fraction of the cost.

The core functionality of this device relies on the MT6701 magnetic encoder, which precisely tracks the orientation of the surrounding magnetic field. This encoder is held in place with a 3D-printed jig behind the small touchscreen, hiding the encoder without blocking the magnetic field generated by the magnet above the display. Most circular magnets are axially magnetized, meaning their larger face is one pole. However, diametrically magnetized magnets, where opposite sides of the smaller face are the poles, are used here.

To avoid scratching the screen and ensure smooth turning, [upir] designed a knob that holds the diametrically magnetized magnet slightly above the screen, with a ball bearing connecting the outside of the knob to the center resting on the screen. All the design files needed to recreate this are available on [upir]’s GitHub page; be sure to check them out. Also, browse through our back catalog for other knob-related projects.

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