Building A Human-Sized Pop-Pop Boat

Pop-pop boats are a neat little science teaching tool that many children end up playing with at some point or other. They’re normally sized to float around a sink or bathtub. [Steve Mould] recently got the opportunity to board a much larger example,  sized for an actual human passenger.

The boat belongs to the The AHHAA Science Center in Estonia, along with a smaller model about half the size. Both are fired by propane gas burners to give them some real heat output into the water tank, far beyond what you’d get from little tea light candles. In the case of the larger boat, it uses a series of valves to allow the tank to be filled with water while the rear thrust pipes are closed.

At the larger scale, it’s more easy to visualize the flow out of the boat’s rear outlets. It’s by no means a fast way to get around on the water, with a top speed somewhat less than walking pace. It’s also very loud. Regardless, it’s amusing to see the pop-pop engine work even when scaled up to full size.

If you’re looking for an in-depth explanation of how pop-pop boats work, [Steve Mould] has covered that previously. Video after the break.

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10-Foot High 3D Printer Based On Ender 3

There are two main ways to 3D print large things. You can either make lots of small 3D prints and stick them together, or you can use a larger 3D printer. [Emily the Engineer] went the latter route by making her Ender 3 a full 10 feet tall.

The best Doug Dimmadome hat we’ve seen in a while, printed on the 10-foot Ender 3. If you’re unfamiliar, Doug Dimmadome is the owner of the Dimmsdale Dimmadome.

The Ender 3’s modular construction made this feat straightforward in the early steps. The printer was simply disassembled, with longer aluminium extrusions bolted in their place. New wheels were resin printed via Onshape to to run along the new extrusions, which were of a slightly different profile to the original parts. Wiring was also a hurdle, with the 10-foot printer requiring a lot longer cables than the basic Ender 3.

An early attempt to make the Z-axis work with a very long threaded rod failed. Instead, a belt-driven setup was subbed in, based on existing work to convert Ender 3s to belt drive. With a firmware mod and some wiring snarls fixed, the printer was ready to try its first high print. Amazingly, the printer managed to complete a print at full height, albeit the shaking of the tall narrow print lead to some print quality issues. The frame and base were then expanded and some struts installed to add stability, so that the printer could create taller parts with decent quality.

While few of us would need a 10-foot high Ender 3, it’s easy to see the value in expanding your printer’s build volume with some easy mods. [Emily] just took it to the extreme, and that’s to be applauded. Video after the break.

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Fixing A C64 With A Cheap $20 Oscilloscope

Modern computers are so fast and complex that we would seldom try and fix them on a component level with simple DIY tools. Working on an early 1980s computer is much easier by comparison, with the fastest signals often in the single-MHz range. [Sayaka] demonstrates this by using a cheap $20 oscilloscope to troubleshoot and repair a Commodore 64.

After powering it up for the first time, the C64 displays a BASIC prompt, but none of the keys seem to work. [Sayaka] did what good hackers do, and immediately disassembled it to try and figure out the problem, suspecting the CIA chip as a likely culprit.

[Sayaka] elected to purchase a cheap DS0138 oscilloscope kit to help troubleshoot the C64. It’s not the most capable thing, with a bandwidth of just 200 KHz, but it’s enough to do some work on an old retro machine. After probing around to check a number of signals, she noted that the CIA’s pins seemed to be very oxidized and suffering poor conductivity. All it took from there was a resolder job, and the computer was repaired.

We’ve seen other cheap scopes with altogether more impressive specs, too. Video after the break. Continue reading “Fixing A C64 With A Cheap $20 Oscilloscope”

Simple STM32 Frequency Meter Handles Up To 30MHz With Ease

[mircemk] had previously built a frequency counter using an Arduino, with a useful range up to 6 MHz. Now, they’ve implemented a new design on a far more powerful STM32 chip that boosts the measurement range up to a full 30 MHz. That makes it a perfect tool for working with radios in the HF range.

The project is relatively simple to construct, with an STM32F103C6 or C8 development board used as the brains of the operation. It’s paired with old-school LED 7-segment displays for showing the measured frequency. Just one capacitor is used as input circuitry for the microcontroller, which can accept signals from 0.5 to 3V in amplitude. [mircemk] notes that the circuit would be more versatile with a more advanced input circuit to allow it to work with a wider range of signals.

It’s probably not the most accurate frequency counter out there, and you’d probably want to calibrate it using a known-good frequency source once you’ve built it. Regardless, it’s a cheap way to get one on your desk, and a great way to learn about measuring and working with time-varying signals. You might like to take a look at the earlier build from [mircemk] for further inspiration. Video after the break.

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Building A Woodworking Lathe From Scratch

Today, cheap dodgy machine tools are more readily available than ever. Sometimes though, there’s great value in putting a simple and rugged version of your own, as demonstrated by [bartworker]’s woodworking lathe build. 

The core of the build is a hefty wooden base, something that is a core component of any good machine tool. It was built from a large beam sourced from a ship supply house, and originally used to hold a sturdy vice. It eventually gained a motor from a cement mixer when [bartworker] decided it should be converted into a lathe. From there, it was further equipped with a sliding support for larger workpieces, allowing [bartworker] to lathe some seriously big stock.

The lathe is very much an ever-evolving thing, and [bartworker] has used it to share the joys of woodworking with his family and friends. As a demonstration of its abilities, the lathe was able to produce a handsome handle for [bartworker]’s axe.

As this story shows, the only thing better than a tool you build yourself is one that your friends get to enjoy too! Meanwhile, if you’ve been whipping up your own machinery, don’t hesitate to drop us a line!

The Oldest Living Torrent Is 20 Years Old

Twenty years ago, in a world dominated by dial-up connections and a fledgling World Wide Web, a group of New Zealand friends embarked on a journey. Their mission? To bring to life a Matrix fan film shot on a shoestring budget. The result was The Fanimatrix, a 16-minute amateur film just popular enough to have its own Wikipedia page.

As reported by TorrentFreak, the humble film would unknowingly become a crucial part of torrent history. It now stands as the world’s oldest active torrent, with an uptime now spanning a full 20 years. It has become a symbol of how peer-to-peer technology democratized distribution in a fast-changing world.

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Inverse Vaccines Could Help Treat Autoimmune Conditions

Autoimmune diseases occur when the immune system starts attacking the body’s own cells. They can cause a wide range of deleterious symptoms that greatly reduce a patient’s quality of life. Treatments often involve globally suppressing the immune system, which can lead to a host of undesirable side effects.

However, researchers at the University of Chicago might have found a workaround by tapping into the body’s own control mechanisms. It may be possible to hack the immune system and change its targeting without disabling it entirely. The new technique of creating “inverse vaccines” could revolutionize the treatment of autoimmune conditions.

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