Misc Hacks

4031 Articles

Old BBC Micro Gets Some Disk Help From A Raspberry Pi

December 19, 2024 by 15 Comments

[Peter Mount] had a simple problem. He’d treated himself to a retro purchase in the form of a BBC Master 128—a faster sequel to the BBC Micro Model B. The only problem was he needed a way to get software on to it. Cue a creative hack using a Raspberry Pi Zero W.

When [Peter] received the machine, it already had a GoTek floppy emulator, which pulled disk images off a USB drive. However, he wanted an easier and quicker way to get disk images to and from the machine for development purposes. Swapping the USB drive to and from another machine seemed too tedious.

Instead, he decided to swap in a Pi Zero W for this purpose, setting it up to emulate a flash drive by following instructions from MagPi Magazine. This would allow him to use the SCP tool to copy disk images over to the Pi Zero W via its WiFi connection. Basically, the Pi Zero W was acting as a wirelessly-updated storage device hooked up to the GoTek floppy emulator.

It’s a nifty way of doing things. [Peter] could have set about creating his own floppy emulator from scratch with wireless capability included. However, there was no need. He just needed a wirelessly-accessible USB drive, and the Pi Zero W was more than happy to act in that role.

The BBC Micro is a beloved machine of many in the British Isles, and it had rather an extended family. If you’ve pulled off your own nifty hack on this classic machine, be sure to hit us up on the tipsline!

Getting Dial-Up To Work Over VOIP Isn’t Always Easy

December 19, 2024 by 26 Comments

Dial-up modems used to be the default way of accessing the Internet, but times have moved on. They’re now largely esoteric relics from a time gone by. With regular old phone lines rather hard to come by these days, [Peter Mount] decided to try getting a pair of dial-up modems working over VoIP instead.

The build started with a pair of Linksys PAP2T VoIP phone adapters, which were originally designed for hooking regular phones up to VoIP systems. He paired each US Robotics modem with a PAP2T, and then hooked both into a VoIP Private Branch Exchange which he set up using 3cx on a Raspberry Pi 3B+. The Pi also acted as a server for the modems to connect to. It took a lot of fiddly configuration steps, but he found success in the end. On YouTube, he demonstrates the setup—with that glorious modem sound—communicating successfully at a rate of 9600 baud.

It’s nice to see this vintage hardware communicating in a what is effectively a simulated world created entirely within modern hardware. We’ve seen similar projects before, like this attempt to get dial-up going over Discord. If you’re doing your own odd-ball screechy communications experiments, don’t hesitate to drop us a line!

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Homebrew Electron Beam Lithography With A Scanning Electron Microscope

December 19, 2024 by 8 Comments

If you want to build semiconductors at home, it seems like the best place to start might be to find a used scanning electron microscope on eBay. At least that’s how [Peter Bosch] kicked off his electron beam lithography project, and we have to say the results are pretty impressive.

Now, most of the DIY semiconductor efforts we’ve seen start with photolithography, where a pattern is optically projected onto a substrate coated with a photopolymer resist layer so that features can be etched into the surface using various chemical treatments. [Peter]’s method is similar, but with important differences. First, for a resist he chose poly-methyl methacrylate (PMMA), also known as acrylic, dissolved in anisole, an organic substance commonly used in the fragrance industry. The resist solution was spin-coated into a test substrate of aluminized Mylar before going into the chamber of the SEM.

As for the microscope itself, that required a few special modifications of its own. Rather than rastering the beam across his sample and using a pattern mask, [Peter] wanted to draw the pattern onto the resist-covered substrate directly. This required an external deflection modification to the SEM, which we’d love to hear more about. Also, the SEM didn’t support beam blanking, meaning the electron beam would be turned on even while moving across areas that weren’t to be exposed. To get around this, [Peter] slowed down the beam’s movements while exposing areas in the pattern, and sped it up while transitioning to the next feature. It’s a pretty clever hack, and after development and etching with a cocktail of acids, the results were pretty spectacular. Check it out in the video below.

It’s pretty clear that this is all preliminary work, and that there’s much more to come before [Peter] starts etching silicon. He says he’s currently working on a thermal evaporator to deposit thin films, which we’re keen to see. We’ve seen a few sputtering rigs for thin film deposition before, but there are chemical ways to do it, too.

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Robot Air Hockey Player Predicts Your Next Move

December 16, 2024 by 21 Comments

Air hockey is a fun game, but it’s one you can’t play by yourself. That is, unless you have a smart robot hockey player to act as your rival. [Zeroshot] built exactly that.

The build is based around a small 27-inch air hockey table—not exactly arcade-spec, but big enough to demonstrate the concepts at play. The robot player moves its mallet in the X and Y axes using a pair of NEMA17 stepper motors and an H-belt configuration. To analyze the game state, there’s a Raspberry Pi 3B fitted with a camera, and it has a top-down view of the board. The Pi gives the stepper motors commands on how to move the mallet via an Arduino that communicates with the stepper drivers.  The Pi doesn’t just aim for the puck itself, either. With Python and OpenCV, it tries to predict your own moves by tracking your mallet, and the puck, too. It predicts the very-predictable path of the puck, and moves itself to the right position for effective defence.

Believe it or not, we’ve featured quite a few projects in this vein before. They’ve all got their similarities, and their own unique quirks. Video after the break.
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The Disappearing Capacitor

December 12, 2024 by 25 Comments

As part of a phosphorescence detector, [lcamtuf] has been working with photodiodes. The components, like all diodes, have some capacitance at the junction, and this can limit performance. That’s why [lcamtuf] turned to bootstrapping to make that parasitic capacitance almost disappear.

The technique appears in several Analog Devices datasheets that presents a mystery. An op amp circuit that would normally limit changes to about 52 kHz has an unusually-placed JFET and claims to boost the bandwidth to 350 kHz.

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Creating A Radiation King Radio In The Real World

December 10, 2024 by 14 Comments

If you’re a fan of the Fallout series of games, you’ve probably come across a Radiation King radio before. In the game, that is, they don’t exist in real life. Which is precisely why [zapwizard] built one!

Externally, the design faithfully recreates the mid-century design of the Radiation King. It’s got the louvered venting on the front panel, the chunky knobs, and a lovely analog needle dial, too. Inside, it’s got a Raspberry Pi Zero which is charged with running the show and dealing with audio playback. It’s paired with a Pi Pico, which handles other interface tasks.

It might seem simple, but the details are what really make this thing shine. It doesn’t just play music, it runs a series of simulated radio stations which you can “tune into” using the radio dial. [zapwizard dives into how it all works—from the air core motor behind the simulated tuning dial, to the mixing of music and simulated static. It’s really worth digging into if you like building retro-styled equipment that feels more like the real thing.

It’s not just a prop—it’s a fully-functional item from the Fallout universe, made manifest. You know how much we love those. If you’re cooking up your own post-apocalyptic hacks, fictional or non-fictional, don’t hesitate to let us know.

Rolling Your Own Ball Screws

December 4, 2024 by 24 Comments

We’ve got mixed feelings about a new video from [AndysMachines] that details how he makes custom ball screws. On the one hand, there’s almost zero chance that we’ll ever have an opportunity to put this information to practical use. But on the other hand, the video gives a fantastic look at the inner workings and design considerations for ball screws, which is worth the price of admission alone

The story behind these ball screws is that [Andy] is apparently in cahoots with SkyNet and is building a T-800 Terminator of his own. Whatever, we don’t judge, but the build requires a short-throw linear drive mechanism that can be back-driven, specs that argue for a ball screw. [Andy] goes through the challenges of building such a thing, which mainly involve creating threads with a deep profile and wide pitch. The screw itself wasn’t too hard to cut, although there were some interesting practical details in the thread profile that we’d never heard of before.

The mating nut was another. Rather than try to cut deep internal threads, [Andy] took a sort of “open-face sandwich” approach, creating half-nuts in a single piece of brass using a CNC machine and a ball-nose mill. The threads were completed by cutting the two halves apart and bolting them together — very clever! [Andy] also showed how the balls recirculate in the nut through channels cut into one of the half-nuts.

Whether the results were worth the effort is up to [Andy], but we were just glad to be along for the ride. And if you want a little more detail on lead screws and ball screws, we’ve got just the article for that.

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