March To The Beat Of Your Own Piezoelectric Drum

September 20, 2025 by No comments

Drums! You hit them, and they vibrate. It’s kind of fun. Piezoelectric elements can create electric current when they vibrate. [Will Dana] put two and two together to try and charge his phone on his YouTube channel WillsBuilds embedded below.

It worked… about as well as you might expect. Which is to say: not very well. The random piezo elements [Will] glues to his drum almost certainly aren’t optimized for this use case. Adding weight helps, but it doesn’t look like a tuned system. Even if it was, piezoelectric generators aren’t terribly efficient by nature, and the (small) losses from the required bridge rectifiers aren’t helping. An energy-harvesting chip might have worked better, but it probably wouldn’t have worked well.

Since he cannot produce enough voltage in real time, [Will] opts to charge a capacitor bank that he can dump into the phone once it gets enough charge in it to register with the phone’s circuitry. It takes about 30 minutes drumming to charge the capacitors in parallel, before switching to series to get the voltage up to discharge. The capacitors drain in about a quarter second, probably to no measurable result– but the phone does read as “charging”, which was the goal.

Did it work? Technically, yes. The phone was “charging”. Is it practical? Certainly not. Is it a hack? Undeniably so.

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When Low SRAM Keeps The DOOM Off Your Vape

September 20, 2025 by 2 Comments

The PIXO Aspire is a roughly $35 USD vape that can almost play DOOM, with [Aaron Christophel] finding that the only thing that realistically stops it from doing so is that the Cortex-M4-based Puya PY32F403XC MCU only has 64 kB of SRAM. CPU-wise it would be more than capable, with a roomy 16 MB of external SPI Flash and a 323×173 pixel LC touch screen display covering the other needs. It even has a vibration motor to give you some force feedback. Interestingly, this vape has a Bluetooth Low-Energy chip built-in, but this does not seem to be used by the original Aspire firmware.

What [Aaron] did to still get some DOOM vapors on the device was to implement a screenshare firmware, allowing a PC to use the device as a secondary display via its USB interface. This way you can use the regular PC mouse and keyboard inputs to play DOOM, while squinting at the small screen.

Although not as completely overpowered as a recent Anker charging station that [Aaron] played DOOM on, we fully expect vapes in a few years to be perfectly usable for some casual gaming, with this potentially even becoming an original manufacturer’s function, if it isn’t already.

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A black, rectangular box is shown, with a number of waterproof screw connectors on the front.

A Ruggedized Raspberry Pi For Sailors

September 20, 2025 by 6 Comments

Nautical navigation has a long history of innovation, from the compass and chronometer to today’s computer-driven autopilot systems. That said, the poor compatibility of electronics with saltwater has consequently created a need for rugged, waterproof computers, a category to which [Matti Airas] of Hat Labs has contributed with the open-source HALPI2.

Powered by the Raspberry Pi Compute Module 5, the electronics are housed in a heavy duty enclosure made of aluminium, which also serves as a heat sink, and closes with a waterproof seal. It has a wide variety of external connectors, all likewise waterproofed: power, HDMI, NMEA 2000 and NMEA 0183, Ethernet, two USB 3.0 ports, and an external WiFi or Bluetooth antenna. The external ports are plugged into the carrier board by short extension cables, and there are even more ports on the carrier board, including two HDMI connectors, two MIPI connectors, four USB ports, and a full GPIO header. The case has plugs to install additional PG7 or SP13 waterproof connectors, so if the existing external connectors aren’t enough, you can add your own.

Besides physical ruggedness, the design is also resistant to electrical damage. It can run on power in the 10-32 volt range, and is protected by a fuse. A supercapacitor bank preserves operation during a power glitch, and if the outage lasts for more than five seconds, can keep the system powered for 30-60 seconds while the operating system shuts down safely. The HALPI2 can also accept power over NMEA 2000, in which case it has the option to limit current draw to 0.9 amps.

The design was originally created to handle navigation, data logging, and other boating tasks, so it’s been configured for and tested with OpenPlotter. Its potential uses are broader than that, however, and it’s also been tested with Raspberry Pi OS for more general projects. Reading through its website, the most striking thing is how thoroughly this is documented: the site describes everything from the LED status indicators to the screws that close the housing – even a template for drilling mounting holes.

Given the quality of this project, it probably won’t surprise you to hear this isn’t [Matti]’s first piece of nautical electronics, having previously made Sailor HATs for the ESP32 and the Raspberry Pi.

Venus Climate Orbiter Akatsuki’s Mission Has Ended

September 20, 2025 by 1 Comment

Japan’s Venus Climate Orbiter Akatsuki was launched on May 21, 2010, and started its active mission in 2015 after an initial orbital insertion failure. Since that time, Akatsuki has continuously observed Venus from orbit until issues began to crop up in 2024 when contact was lost in April of that year due to attitude control issues. Japan’s space agency, JAXA, has now announced that the mission has officially ended on September 18, 2025, after a period of trying to coax the spacecraft back into some level of functionality again.

The Akatsuki spacecraft in 2010 before its launch. (Credit: JAXA)
The Akatsuki spacecraft in 2010 before its launch. (Credit: JAXA)

The Akatsuki spacecraft had six instruments, consisting of cameras covering the visible spectrum, ultraviolet and infrared spectra, as well as an oscillator for radio occultation experiments.

All primary mission goals were successfully completed in April of 2018, but engineers determined Akatsuki was capable of lasting at least another few years. This puts it well past its original design lifespan, and has provided us with much more scientific data than we could have hoped for.

Unfortunately, the shutdown of Akatsuki represents the end of the last active Venus mission, with much uncertainty surrounding any potential upcoming mission to Earth’s near-twin planet. The next potential mission is the Venus Life Finder, as an atmospheric mission penciled in for a 2026 launch. It would take at least until 2028 for a potential orbiter mission to launch, so for the foreseeable future Venus will be left alone, without its artificial moon that has kept it company for a decade.

Regretfully: $3,000 Worth Of Raspberry Pi Boards

September 20, 2025 by 21 Comments

We feel for [Jeff Geerling]. He spent a lot of effort building an AI cluster out of Raspberry PI boards and $3,000 later, he’s a bit regretful. As you can see in the video below, it is a neat build. As Jeff points out, it is relatively low power and dense. But dollar for dollar, it isn’t much of a supercomputer.

Of course, the most obvious thing is that there’s plenty of CPU, but no GPU. We can sympathize, too, with the fact that he had to strip it down twice and rebuild it for a total of three rebuilds. One time, he decided to homogenize the SSDs for each board. The second time was to affix the heatsinks. It is always something.

With ten “blades” — otherwise known as compute modules — the plucky little computer turned in about 325 gigaflops on tests. That sounds pretty good, but a Framework Desktop x4 manages 1,180 gigaflops. What’s more is that the Framework turned out cheaper per gigaflop, too. Each dollar bought about 110 megaflops for the Pis, but about 140 for the Framework.

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Computer Has One Instruction, Many Transistors

September 20, 2025 by 9 Comments

There’s always some debate around what style of architecture is best for certain computing applications, with some on the RISC side citing performance per watt and some on the CISC side citing performance per line of code. But when looking at instruction sets it’s actually possible to eliminate every instruction except one and still have a working, Turing-complete computer. This instruction is called subleq or “subtract and branch if less-than or equal to zero“. [Michael] has built a computer that does this out of discrete components from scratch.

We’ll save a lot of the details of the computer science for [Michael] or others to explain, but at its core this is a computer running with a 1 kHz clock with around 700 transistors total. Since the goal of a single-instruction computer like this is simplicity, the tradeoff is that many more instructions need to be executed for equivalent operations. For this computer it takes six clock cycles to execute one instruction, for a total of about 170 instructions per second. [Michael] also created an assembler for this computer, so with an LCD screen connected and mapped to memory he can write and execute a simple “hello world” program just like any other computer.

[Michael] does note that since he was building this from Logisim directly he doesn’t have a circuit schematic, but due to some intermittent wiring issues might have something in the future if he decides to make PCBs for this instead of using wire on a cardboard substrate. There’s plenty of other information on his GitHub page though. It’s a unique project that gets to the core of what’s truly needed for a working computer. There are a few programming languages out there that are built on a similar idea.

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“Simplest” Oscilloscope Is A Cunning Vector Display

September 20, 2025 by 10 Comments

Superlatives are tricky things. [mircemk]’s guide “How to make Simplest ever Oscilloscope Clock” falls into that category. It’s that word, simplest. Certainly, this is an oscilloscope clock, and a nice one. But is it simple?

There’s a nice oscilloscope circuit with a cute 2″ 5LO38I CRT and EF80 tubes for horizontal and vertical deflection that we’d say is pretty simple. (It’s based on an earlier DIY oscilloscope project [mircemk] did.) The bill of materials is remarkably sparse– but it’s modules that do it. One entry is a DC-DC step up supply to get the needed HV. Another is a LM317 to get 6.3 V to heat the tubes. The modules make for a very simple BOM, but on another level, there’s quite a bit of complex engineering in those little modules.

When we get to the “clock” part of the oscilloscope clock, that quandary goes into overdrive. There’s only one line on the BOM, so that’s very simple. On the other hand, it’s an ESP32. Depending on your perspective, that’s not simple at all. It’s a microcomputer, or at least something that can play at emulating one.

Oh, in the ways that matter to a maker — parts count, time, and effort, this oscilloscope clock is very simple. The fact that its actually a vector display for a powerful little micro just adds to the versatility of the build. We absolutely love it, to be honest. Still, the idea that you can have millions of transistors in a simple project — never mind the “simplest ever” — well, it just seems weird on some level when you think about it.

It all comes back to what counts as “simple”. If we’re taking lines on a BOM, arguably this would be even simpler if you used an existing oscilloscope.