Mysterious Files PH

For a little while vacuum tubes and semiconductors were fighting a heated battle for dominance, with bipolar junction transistors and 1959’s RCA Nuvistor both allowing you to build a compact circuit with relatively low power usage and no high voltages. Although we now know that semiconductor technology won out overwhelmingly, that doesn’t mean that you cannot build a brand new Nuvistor board in 2026, as [Eric Schlaepfer] AKA [TubeTimeUS] recently did.

Nuvistors saw their most use in small-signal radio frequency applications, like VHF and UHF, with excellent low-noise characteristics that saw them used until the early 1970s in television sets, radios and oscilloscopes, as well as in space probes like the 1960s US Ranger Moon missions, so by that metric they had a good run.

Nothing so exciting is built in this video, sadly, but alongside a breakdown on how nuvistors work, we do see a discrete 555-style timer built using a gaggle of tetrode nuvistors, giving a pretty good idea of what using them in a project is like. Being a vacuum tube at its core, nuvistors still have the heater element, which is what gives vacuum tubes their reputation for being slow to start working and large current draw.

Despite their drawbacks, nuvistors still have a range of benefits compared to modern-day transistors, including being practically immune to electrostatic discharge (ESD) and electromagnetic interference (EMI) all the way up an EMP that will destroy most semiconductor electronics.

That said, the somewhat limited 8-nuvistor implementation of the 555 had to get a few extra pins for the heater supply, which burns up about 7.5 Watt just to allow the circuit to function. Terming it the ‘hollow-state 555 timer’, it works effectively just like any semiconductor 555, just with that extra power cost and of course no significant prospect of making it smaller, barring a semiconductor evolution as with the pixels-sized CRTs in the SED and FED type displays.

We covered the nuvistor before, including a great reference on this device, and its history that was much longer than people often assume today, as well as the vacuum tubes we use every day in for example our microwaves.

Nintendo has made many game consoles in its long history — one that famously overlaps that of the Ottoman Empire — but only one of them was ever Super. It’s that console, the Super Nintendo Entertainment System, that [Inkbox] has decided to delve deeply into as he crafts a game in assembly using all the hardware tricks he can.

Hardware tricks he’ll need, given he’s limited to the two 64 kB RAM banks and 3.58 MHz Ricoh 6502-based CPU. Even the 4 MB limit he sets for a historically-accurate homemade cartridge seems positively claustrophobic by modern standards. The game he’s after making is a top-down adventure game a la Zelda, and [Inkbox] gets right into the weeds explaining how the SNES works as he shows his work in this nearly hour long video. If you’re looking for a deep dive into the architecture, along with how it is meant to be used, you could certainly find worse sources. Everything from the different graphics modes to what registers handle sound are covered in this and the previous video in the series.

We can’t help but call out his dedication to open source — the SNES Sound Engine he has put up on GitHub looks like it could be a real asset to anyone else doing this kind of homebrew. The game itself is on itch.io and is pay-what-you-want.

[Inkbox] doesn’t just limit himself to the SNES’s 6502-esqe assembly — he’s done impressive work in x86 ASM, too.

In this specially-numbered podcast episode that lines up quite nicely with our Retrocomputing Challenge, Elliot Williams and Kristina Panos met over surprisingly low-latency and loud beverages to bring you the best of the previous week’s hacks.

But first, the news. German company Isar Aerospace can now claim that they’ve launched the first spacecraft into orbit from Europe. Be sure to check out the in-link, where we reported on the building of the spaceport.

In Hackaday news, the aforementioned Retrocomputing Contest had 64 entries at last check, which is just perfect for Episode 386. Will yours be the 65th?

Supercon Ten tickets are selling out, and per Elliot, the talks have been chosen, pending approval by each submitter.  Keep an eye on the blog for the official announcement!

After reviewing the news, Elliot reached into the ol’ Mailbag and found two missives, including another from [Vik Olliver] regarding the printing of LEGO. The other is from [Mendel Munkis], who has been enjoying Wikipedia offline since 2018, thanks to a 32-bit ARM9 processor. Then, it was on to the hacks.

Check out the links below if you want to follow along, and as always, tell us what you think about this episode in the comments!

Download in lovely MP3.

Episode 386 Show Notes:

News:

• The First Spacecraft Launched To Orbit From Europe
• Announcing The 2026 Hackaday Retrocomputing Challenge
• Retro Computing Contest
• Wikipedia: Unusual articles

Mailbag:

• This week, we have a double feature!

Interesting Hacks of the Week:

• Making A Pole Balance Itself With Propellers
  • 3D-Printed Self-Balancing Robot Brings Control Theory To Life
• Free Your Rotary Telephone From Its Wire
  • • Simplify Your Life With This Pocket Rotary Cellphone
    • The Open Source Rotary Cell Phone, Two Years Later
    • Using Old Phones As An Intercom In Your VW Bus (or Anywhere Else)
    • Wikipedia: Intercept messages
    • This Is a Recording
• Printing Micron-Scale Benchies With Resin And Turmeric
  • GitHub – 0x23/MicroManipulatorStepper: A sub-micrometer 3D motion control plattform. · GitHub
• This Clavichord Is A Well-Tempered Project
• The Different Ways To Look At Negative Resistance
• There’s A Whole Computer Inside This Mouse

Quick Hacks:

• Elliot’s Picks:
  • If It’s Electronic Paper, Why Not Print To It?
  • 3D Printable Lenticular Indicators
  • The Helicopter With Radioactive Blades
• Kristina’s Picks:
  • A Split Keyboard Designed For Human Hands
  • Take Tool Photo, Generate Custom Gridfinity Bin
  • Anti-Doomscroll Tamagotchi Only Lives If You Do

Can’t-Miss Articles:

• Hackaday Europe 2026: Outdoors With Robots
• Hunting The Wild Vibrotruck

The revival in film photography has brought a range of specialist films to tempt the experimenter, as well as increased the popularity of loading your own cartridges. But perforating the film from blank stock has always been beyond the reach of home gamers. Now [Jon Schiereck] has done it, but not quite with film. He’s made a perforator for photographic paper, producing a strip which can be shot in a camera. It’s film, but it’s not exactly film.

The machine takes the form of a 3D printed mechanism which feeds a strip of photographic paper through a pair of punches to make the sprocket holes. In this case those holes are circular, being made by a pair of drill bits ground for the purpose, and they’re moved up and down by a crank driven by a set of gears from a hand crank or even a cordless drill. A rubber roller pulls the film forward.

It seems to be a well-thought-out machine, and you can try it yourself for free via a slightly unusual distribution medium, his Ko-Fi page. In case you’re worried about finding a slitter to make those 35mm paper strips, it seems he’s also working on a 3D printable one of those. So you can shoot on paper, and develop it just as you would a print.

If you’re further into extending what you can film through the use of a 3D printer, how about 8 mm movie film?

A fun part of modifying something like a motorbike is that you sometimes have to come up with creative solutions to basic questions, like how you can still access the fuel tank’s cap after extending it forward. In the case of [KRTframework] this meant that the fuel cap was now underneath the bodywork, requiring a suitable way to access it. Of course, this meant making a hidden access panel with a custom hinge, to not break the bike’s clean lines.

To make the process as easy as possible, a 3D scanner was used to get detailed measurements on what the new bodywork would look like. Using these the new bodywork was created, including what would be the hidden access panel, yet finding a suitable hinge mechanism wasn’t easy. This is where this custom design was created, with detailed assembly covered in the video.

To bridge the gap between the opening and the fuel tank a part was 3D-printed that also contains the simple push-to-open latch mechanism. Of course, in the comment section people sounded off on this, feeling that it would be far too easy to accidentally open the panel.

The hinge seems to be well-received at least, with it having to fit within the available space, while also providing good access to the fuel cap when opened, meaning quite a lot of travel.

Remember those tiny little droids skittering around the pristine corridors of the Death Star in Star Wars? [heychaostheory] has put together something vaguely along the lines of those charming little mobile toasters. It’s an autonomous mouse droid with party mode!

The build is interesting in that it’s based on an off-the-shelf metal robot chassis—which provides mounting points for the gearmotors and wheels that make up the drivetrain. The mouse droid body sits atop this, being a 3D printed part that is afixed with heat set inserts and nylon standoffs. It’s 3D printed and expertly decorated with a fun vibe. Inside the body lives an Arduino Uno, hooked up to an L298 motor driver board and ultrasound sensors used for obstacle avoidance. It’s also got a smattering of LEDs to flash, because blinkenlights matter. The best bit, though, is the party mode button, which fires off music via a DFPlayer Mini module.

The mouse droid may not be as flashy and imposing as the Droideka or as mechanically impressive as BB-8, but that just makes it more accessible and fun to build. You can easily create one at full scale without breaking the bank. If you’re cooking up your own fun droids in the workshop, don’t hesitate to let us know. Video after the break.

There are plenty of ways to capture 3D images or simulations of such if you know what you’re doing with camera hardware and fancy mathematics. However, a little more unusual is the idea of capturing a 3D image while using no lens at all — and yet, [okooptics] has achieved just that!

The basic concept builds on an older project from [okooptics], wherein images were captured from a Raspberry Pi camera with no regular lens element installed. In its place was a thin layer of Scotch tape over the sensor, acting as a diffuser. With the right deconvolution math, it’s possible to actually recover a real image out of the blurry mess this setup initially captures. [okooptics] was then able to push this into three dimensions by weighting the point spread function used to deconvolute the image.

Adding directional bias to the process creates a similar effect to slightly shifting the cameras position, actually revealing a view from a slightly different angle of objects in front of the camera. [okooptics] does a great job of explaining the science behind how this is possible and the practical limitations of the technique, also referencing research papers that have explored these ideas in great depth.

It’s math heavy to extract 3D data from what otherwise looks like blurry nothingness, but it’s possible if you know what you’re doing. For a fuller understanding, it’s worth diving into [okooptics] earlier work in this realm, taking photos with Scotch tape in place of a lens.