Day: April 8, 2025

Salamander Robot Is Squishy

April 8, 2025 by 7 Comments

If you want to get started in microfluidic robotics, [soiboi soft’s] salamander is probably too complex for a first project. But it is impressive, and we bet you’ll learn something about making this kind of robot in the video below.

The pneumatic muscles are very impressive. They have eight possible positions using three sources of pressure. This seems like one of those things that would have been nearly impossible to fabricate in a home lab a few decades ago and now seems almost trivial. Well, maybe trivial isn’t the right word, but you know what we mean.

The soft robots use layers of microfluidic channels that can be made with a 3D printer. Watching these squishy muscles move in an organic way is fascinating. For right now, the little salamander-like ‘bot has a leash of tubes, but [soiboi] plans to make a self-contained version at some point.

If you want something modular, we’ve seen Lego-like microfluidic blocks. Or, grab the shrinky dinks.

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Dozens Of Solenoids Turn Vintage Typewriter Into A Printer

April 8, 2025 by 16 Comments

An electric typewriter is a rare and wonderful thrift store find, and even better if it still works. Unfortunately, there’s not as much use for these electromechanical beauties, so if you find one, why not follow [Konstantin Schauwecker]’s lead and turn it into a printer?

The portable typewriter [Konstantin] found, a Silver Reed 2200 CR, looks like a model from the early 1980s, just before PCs and word processing software would sound the death knell for typewriters. This machine has short-throw mechanical keys, meaning that a physical press of each key would be needed rather than electrically shorting contacts. Cue the order for 50 low-voltage solenoids, which are arranged in rows using 3D printed holders and aluminum brackets, which serve as heat sinks to keep the coils cool. The solenoids are organized into a matrix with MOSFET drivers for the rows and columns, with snubber diodes to prevent voltage spikes across the coils, of course. A Raspberry Pi takes care of translating an input PDF file into text and sending the right combination of GPIO signals to press each key.

The action of the space bar is a little unreliable, so page formatting can be a bit off, but other than that, the results are pretty good. [Konstantin] even managed to hook the printer up to his typewriter keyboard, which is pretty cool, too.

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ASCII To Mainframe

April 8, 2025 by 11 Comments

IBM mainframes are known for very unusual terminals. But IBM made many different things, including the IBM 3151 ASCII terminal, which uses a cartridge to emulate a VT220 terminal. [Norbert Keher] has one and explains in great detail how to connect it to a mainframe.

It had the 3151 personality cartridge for emulating multiple IBM and DEC terminals. However, the terminal would not start until he unplugged it. The old CRT was burned in with messages from an IBM 3745, which helped him work out some of the configuration.

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Designing A Tone Control Properly

April 8, 2025 by 12 Comments

Many years ago, audio equipment came with a tone control, a simple RC filter that would cut or boost the bass to taste. As time passed, this was split into two controls for bass and treble, and then finally into three for bass, mid, and treble. When audiophile fashion shifted towards graphic equalisers, these tone controls were rebranded as “3-band graphic equalisers”, a misleading term if ever we heard one. [Gabriel Dantas] designed one of these circuits, and unlike the simple passive networks found on cheap music centres of old, he’s doing a proper job with active filters.

The write-up is worth a read even if you are not in the market for a fancy tone control, for the basic primer it gives on designing an audio filter. The design contains, as you might expect, a low-pass, a bandpass, and a high-pass filter. These are built around TL072 FET-input op-amps, and an LM386 output stage is added to drive headphones.

The final project is built on a home-made PCB, complete with mains power supply. Audiophiles might demand more exotic parts, but we’re guessing that even with these proletarian components it will still sound pretty good. Probably better than the headphone amplifier featured in a recent project from a Hackaday writer, at least. There’s a build video, below the break.

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The Computers Of EPCOT

April 8, 2025 by 8 Comments

Even if you aren’t a Disney fan, you probably know about EPCOT — Experimental Prototype Community of Tomorrow — a Disney attraction that promised a glimpse of the future. [ErnieTech] takes a glimpse at the UNIVAC computer that ran the operation in the 1980s. A lot of schools had UNIVAC 1100-series computers back in those days, so while you don’t hear as much about them as, say, IBM 360s, there are hordes of people who have used the 1100s, even if they don’t remember it.

EPCOT opened in 1982, and the UNIVAC not only ran the attraction but was also visible as part of the exhibit’s ambiance. They even used the Pepper’s Ghost illusion to superimpose a little man on top of the equipment.

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FreeDOS 1.4 Released

April 8, 2025 by 21 Comments

Even in 2025 there are still many applications for a simple Disk Operating System (DOS), whether this includes running legacy software (including MS-DOS games & Windows 3.x), or (embedded) systems running new software where the overhead of a full-fat Linux or BSD installation would be patently ridiculous.

This is where the FreeDOS project provides a modern, fully supported DOS, with the recent 1.4 release adding a whole range of features and updates to existing components like the FreeCOM command shell. This is the first stable release since 1.3 was released in 2022.

FreeDOS saw its first release in 1994 and has become the de facto replacement for MS-DOS — featuring many improvements to make it work well on modern hardware and a package manager to manage installed software much like on Linux & BSD. The new kernel didn’t quite make it into this release, but it and some other items will be available in the monthly test builds.

You can download the new 1.4 release here, with live & installer CD images, a USB installer and even a Floppy Edition available. System requirements include an (Intel) x86 CPU, a BIOS (or legacy UEFI mode), 640 kB of RAM and 20 MB of storage.

Turning Old Cellphones Into SBCs

April 8, 2025 by 33 Comments

[David] sent us a tip about a company in Belgium, Citronics, that is looking to turn old cellphones into single-board computers for embedded Linux applications. We think it’s a great idea, and have long lamented how many pocket supercomputers simply get tossed in the recycling stream, when they could be put to use in hacker projects. So far, it looks like Citronics only has a prototyping breakout board for the Fairphone 2, but it’s a promising idea.

One of the things that’s stopping us from re-using old phones, of course, is the lack of easy access to the peripherals. On the average phone, you’ve got one USB port and that’s it. The Citronics dev kit provides all sorts of connectivity: 4x USB 2.0, 1x Ethernet 10/100M, and a Raspberry Pi Header (UART, SPI, I2C, GPIO). At the same time, for better or worse, they’ve done away with the screen and its touch interface, and the camera too, but they seem to be keeping all of the RF capabilities.

The whole thing runs Linux, which means that this won’t work with every phone out there, but projects like PostmarketOS and others will certainly broaden the range of usable devices. And stripping off the camera and screen has the secondary advantages of removing the parts that get most easily broken and have the least support from custom Linux distros.

We wish we had more details about the specifics of the break-out boards, but we like the idea. How long before we see an open-source implementation of something similar? There are so many cheap used and broken cellphones out there that it’s certainly a worthwhile project!