Year: 2023

Selectric Typewriter Goes From Trash Can To Linux Terminal

July 25, 2023 by 20 Comments

If there’s only lesson to be learned from [alnwlsn]’s conversion of an IBM Selectric typewriter into a serial terminal for Linux, it’s that we’ve been hanging around the wrong garbage cans. Because that’s where he found the donor machine for this project, and it wasn’t even the first one he’s come across in the trash. The best we’ve ever done is a nasty old microwave.

For being a dumpster find, the Selectric II was actually in pretty decent shape. The first couple of minutes of the video after the break show not only the minimal repairs needed to get the typewriter back on its feet, but also a whirlwind tour of the remarkably complex mechanisms that turn keypresses into characters on the page. As it turns out, knowing how the mechanical linkages work is the secret behind converting the Selectric into a teletype, entirely within the original enclosure and with as few modifications to the existing mechanism as possible.

Keypresses are mimicked with a mere thirteen solenoids — six for the “latch interposers” that interface with the famous whiffletree mechanism that converts binary input to a specific character on the typeball, and six more that control thinks like the cycle bail and control keys. The thirteenth solenoid controls an added bell, because every good teletype needs a bell. For sensing the keypresses — this is to be a duplex terminal, after all — [alnwlsn] pulled a page from the Soviet Cold War fieldcraft manual and used opto-interrupters to monitor the positions of the latch interposers as keys are pressed, plus more for the control keys.

The electronics are pretty straightforward — a bunch of MOSFETs to drive the solenoids, plus an AVR microcontroller. The terminal speaks RS-232, as one would expect, and within the limitations of keyboard and character set differences over the 50-odd years since the Selectric was introduced, it works fantastic as a Linux terminal. The back half of the video is loaded with demos, some of which aptly demonstrate why a lot of Unix commands look the way they do, but also some neat hybrid stuff, like a ChatGPT client.

Hats off to [alnwlsn] for tackling a difficult project while maintaining the integrity of the original hardware.

Continue reading “Selectric Typewriter Goes From Trash Can To Linux Terminal” →

Grab Your ‘Scope’s Screen From The Command Line

July 25, 2023 by 9 Comments

Many of us have oscilloscopes and other instruments with built-in digital interfaces, but how many of us use them? [Andrej Radović] has a Tektronix TDS2022 which can print its screen to any of its various interfaces, and he set about automating the process of acquisition with a Bash script.

The easiest interface to use was the trusty serial port — hardly the fastest but definitely the best supported. But how does one retrieve an image fired down a serial port? Most of the post is devoted to spotting file headers in a Bash script monitoring the serial port, and streaming the result to a local file. There’s a discussion of the various formats supported by the Tek, with an ancient PCX bitmap format being chosen over Postscript for speed. The result is a decent quality screen grab, making the ‘scope that little bit more useful and perhaps extending its life.

Perhaps your instrument isn’t a TEK, but the chances are you can still make it bend to your will from a PC. Try it, with the magic of VISA.

Restoring The Cheapest TRS-80 At The Swap Meet

July 24, 2023 by 20 Comments

We don’t know if you’ve looked into it recently, but the prices for vintage computers are through the roof right now. These classic machines are going through something of a renaissance at the moment, with even relatively commonplace computers commanding several hundred dollars if they’re in good condition. For those looking to start a collection without breaking the bank, you may need to accept some specimens that have seen better days.

That’s the situation [Vlado Vince] recently found himself in — he wanted to get his hands on a TRS-80 Model I, but wasn’t willing to spend eBay prices. So he waited until the Vintage Computer Federation’s swap meet in June and was able to snag a “fully functional” example for $95. Unfortunately the seller must have been using some form of that phrase which we were previously unaware of, as it took a considerable amount of work to get it back online.

Continue reading “Restoring The Cheapest TRS-80 At The Swap Meet” →

DOOM On IPhone OS, On Android

July 24, 2023 by 7 Comments

So you want to play some games from the early days of 32-bit iPhone OS that no longer run on recent OS versions? [Hikari-no-yume] wrote a sweet high-level emulator, touchHLE, to do so on modern iOS phones. But maybe you don’t have an iPhone? [Ciciplusplus] has your back. He ported the iPhone OS emulator, written in Rust, to Android, and then ported a version of DOOM that runs on iPhone OS to go with it.

[Ciciplusplus] also made a video (embedded below) where he documented the trials and tribulations of porting Rust code to the Android platform – an intensely Java environment. It doesn’t sound like it was at all trivial. Of course, this couldn’t have been accomplished without [Hikari-no-yume]’s original work on touchHLE, which was made essentially to fulfill [Hikari-no-yume]’s long-time obsession with the game Super Monkey Ball.

So for now, touchHLE can boast the ability to run a few old 32-bit games on Android and desktop operating systems. What other games from the first years of gaming on smart phones (and iPods) do you need to see ported? Get involved in the project if you’ve got an itch you need scratched.

Continue reading “DOOM On IPhone OS, On Android” →

2023 Hackaday Prize: A Smart Powermeter That You Actually Want

July 24, 2023 by 19 Comments

[Jon] wanted to keep track of his home power use, but didn’t want to have to push his data up to some cloud service that’s just going to leave him high and dry in the future. So he went completely DIY.

This simple and sweet build is now in its third revision, and the refinements show. A first prototype was nothing more than an ESP32 with a screen and some current transformer (CT) sensors to read the current flowing in the wires in his breaker box. The next version added a PCB and a color screen, and the most recent version swapped up to eInk and a nice local power supply, all sized to fit a nice clear power box.

What’s really cute about this design is the use of standard phono headphone jacks to plug the CT sensors into, and the overall sweet combination of a local display and interactivity with [Jon]’s ESPHome-based home automation setup. This design isn’t super complicated, but it doesn’t need to be. It has one job, and it does it nicely. What more do you want?

If you’re interested in getting into ESPHome and/or home automation, check out this great ESPHome resource. It’s probably a lot easier than you think, and you can build your system out one module at a time. If you’re like us, once you get started, you’ll find it hard to stop until everything falls under your watchful eyes, if not your control.

Nail, Meet KiCad

July 24, 2023 by 25 Comments

You know the old saying. When all you have open is KiCad, everything looks like a PCB. That was certainly true for [Evan], who needed to replace a small part recently and turned to PCBs to get the job done.

The part in question was a sheered apart detent cam from a retractable cord reel. Glue and epoxy might have worked, and [Evan] was worried about how a 3D printed PLA part would have held up. The part is an extruded 2D shape, making PCBs a non-traditional but viable choice. Using the old scanner trick, he traced the outline in KiCad 7 (which adds image references). Then with the five boards stacked up, solid core wire, solder, and a propane torch worth of heat fused it. Ultimately, this machine’s tolerances are generous, so it worked wonderfully.

Was it the “right” tool for the job? Right or wrong, it is hard to argue that in terms of durability and ease per dollar, this doesn’t come out on top. PCB files are on GitHub if you have a 5020TF-4c retractable cord reel that needs a new cam. PCBs have a fun way of adopting different use cases like enclosures, but perhaps the idea of PCBs as a mechanical part could be applied elsewhere.

Text-to-Speech Model Can Do Music, Background Noises, And Sound Effects

July 24, 2023 by 8 Comments

Bark is a universal text-to-audio model that can not only create realistic speech, it can incorporate music, background noises, and sound effects. It can even include non-speech sounds like laughter, sighs, throat clearings, and similar elements. But despite the fact that it can deliver such complex results, it’s important to understand some of the peculiarities.

The model takes a prompt and generates the resulting sound from scratch. Results might sometimes be unexpected.

Bark is not a conventional text-to-speech program, and how it works has a lot more in common with large language model AI chatbots. This means that results can deviate from expectations, and outputs aren’t necessarily going to be studio-quality speech. As the project’s README points out, “(generated outputs can) be anything from perfect speech to multiple people arguing at a baseball game recorded with bad microphones.” That being said, there is some support for voice presets as a way to help guide the model with some consistency.

Bark was designed by a company called Suno for research purposes and is available under the MIT License. It can be installed and run locally, and has some demos available as well as an online implementation.

The ability to install and run Bark locally is promising territory for incorporating it into projects. And should you be more interested in speech-to-text instead, don’t forget about this plain C/C++ implementaion of AI-powered speech recognition.