Energizing A Vacuum Tube Flip-Flop Module Of The IBM 604

August 3, 2026 by 2 Comments
Reverse-engineered schematic of the IBM 604's TR-3 module. (Credit: Ken Shirriff)
Reverse-engineered schematic of the IBM 604’s TR-3 module. (Credit: Ken Shirriff)

Taking a break from ogling microscopic features in Intel’s semiconductor processors, [Ken Shirriff] is back to instead poking at decidedly macroscopic pluggable modules from the 1948 IBM 604 Electronic Calculator. This time around it’s one of the so-called trigger modules in the form of the TR-3, which uses a flip-flop circuit to implement the timing signals and pulses that made the 604 work.

This differs from the thyratron module that we covered previously. A thyratron is a high current switch and rectifier, which is useful more for the periphery of the computer system. These TR-3s on the other hand were used to implement the basic logic circuits, even if a flip-flop by itself seems rather boring, being just a circuit that toggles between two states.

In this TR-3 module we find a 2033 dual triode design which thus increases density by having the two inverters of the flip-flop in the same tube. The rest of the module is taken up by the requisite capacitors and resistors that complete the circuit. After wiring up this original module, [Ken] was able to make it trigger somewhat reliably, requiring a stable input trigger.

Notable is that in the IBM 650 from 1954 this flip-flop circuit was abandoned in favor of one based on diode logic, presumably to use more reliable Boolean logic instead of the much fussier analog interactions. Naturally, in the first transistorized computers the use of diode-transistor logic (DTL) was exceedingly common, so this makes a lot of sense.

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Circuit Bending, But Make It MIDI

August 3, 2026 by No comments

Circuit bending is a chaotic art. At its simplest, it can just involve making connections between random points on a circuit board to create weird sounds in musical hardware. Or, you can complicate things, get really specific with your hookups, and twist them with various sorts of modulation. [Simon the Magpie] has been working on something closer to the latter category, with his neat project to add MIDI to the circuit bending world. 

The concept is straightforward enough. [Simon] has created a device that you place in line with your circuit bent connections, particularly those that create pitch bends with pots thanks to their variable resistance. You can then play your MIDI keyboard, and the device will vary the resistance in the circuit and bend the pitch at your command. [Simon] simply calls the device MIDI TO RESISTANCE, because that’s… precisely what it does, with the aid of a digital potentiometer. He then demonstrates it doing its thing on pitchbent toys, and it sounds pretty radical in use.

If you’re trying to make your circuit bent toys and instruments more musical, this build should serve as a great inspiration. We’ve featured other oddball musical hacks in a similarly creative vein before, too—such as using mixers as a synthesizer in their own right. Have fun out there.

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Child-Friendly Music Player Uses RFID

August 3, 2026 by 3 Comments

[David] has a young child who is clever enough to use a computer to play music, but he doesn’t quite want to hand over the mouse just yet. Thus, he set about building an electronic music player that could be operated in an altogether simpler fashion. 

The build is based around an Arduino Nano — its job is to read RFID tags via an RC522 reader, with the tags themselves embedded in a series of small dolls belonging to [David]’s daughter. Upon reading the tag, the Arduino Nano chats over serial with a DFPlayer Mini module, which reads a playlist of MP3 files off of an SD card and plays them over a small 4 ohm speaker that [David] had laying around. It’s a simple build, with the components all neatly wrapped up in a handsome wooden case with a volume control and a skip button for if any one song becomes too annoying for a repeat listen.

We’ve featured other builds in this vein before, too. There’s something satisfying about a music player with such a simple interface—no delicate media to fiddle with, just pop the toy on top and get the playlist you were looking for. If you’re creating your own little musical builds at home, we’d love to see them on the tipsline.

Congratulations To The Frikkin Laser Winners!

August 3, 2026 by 2 Comments

Apparently you all love lasers just as much as we do. We put out a challenge to use, build, or otherwise abuse our favorite coherent light sources, and you responded. Some of the projects had been in the works for quite a while and were ridiculously polished, some were whipped together on the fly just for the contest, and we truly enjoyed both.

We only have three $150 DigiKey gift certificates to give out, though, so without further ado, we present to you…

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New File Manager Is C64’s Answer To Norton Commander

August 3, 2026 by 4 Comments

Norton was always a PC company — Norton Commander, the file manager that launched a thousand clones, was only ever available for DOS, like the rest of the company’s offerings in those days. If they’d decided to port it to the C64, though, it would likely look a lot like [retro3872809] aka [Chicken 64]’s Multi Floppy Commander with Turbo, available on GitLab.

As you might be able to see on the screen shot above or in the demo video below, the application provides an 80-column interface with a split view to show a pair of floppies side-by-side. Not that you’re limited to two floppies, however. The software is happy to swap between all the drives on the bus, to the C64’s maximum of four. All four drives will be usable since the file manager lives on a cartridge.

All drive models are supported, though not all have turbo. As a file manager, it looks like it has the normal functionality you’d expect: renaming, copying, moving and deleting files and directories. You can also launch programs or print disk listings, assuming you have a printer attached to your Commodore.

Said Commodore perhaps needn’t be vintage, as they’re selling new ones again, but if you want a disk drive you may have to fix it yourself.

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The 16K Display That Ate Las Vegas

August 3, 2026 by 16 Comments

You may have a 4K television. Perhaps you have even bought an 8K screen, despite the shortage of things worth watching in 8K. A 16K display is, today, a rarity. But even when those eventually become commonplace, yours probably will not cover 14,900 square meters, rise 73 meters into the air, or wrap over your head and behind your peripheral vision.

That is approximately what happens inside Sphere in Las Vegas. The venue’s interior display is quoted as having a resolution of 16K by 16K and an area of 160,000 square feet, or about 3.7 acres. Unlike most enormous movie screens, it is not illuminated by a projector. The entire surface is a direct-view LED display: an immense, curved video wall assembled from tens of thousands of smaller pieces.

After seeing The Wizard of Oz at Sphere, however, the most interesting part was not simply the screen’s size. It was how thoroughly the screen could disguise itself.

Where Did The Theater Go?

Radio City or the Sphere? (It is the Sphere; photo courtesy [DP])
Before the presentation began, the auditorium appeared to have a conventional architectural ceiling. Great orange ribs curved over the seating, while ventilation grilles, suspended loudspeakers, lighting fixtures, curtains, and video monitors completed the illusion. It looked like the Radio City Music Hall’s proscenium. Then the show started — and the apparent theater completely disappeared. The speakers, the TVs, even the stage.

The obvious first conclusion was that the LED surface must be optically transparent, allowing the audience to see the real roof behind it until the pixels illuminated. That explanation was attractive because Sphere’s audio system really is installed behind the display, and the surface must allow sound through it.

It was also, apparently, wrong. The only explanation that makes sense is that the ceiling, ribs, grilles, speakers, and monitors were already being displayed by the screen. It was like a holodeck impersonating a physical theater interior. When the Oz material began, the system simply replaced one complete visual environment with another.

That’s what happens when a display fills nearly all of your useful visual field. A normal screen announces itself with a bezel, a wall, or at least a clearly visible edge. Sphere’s display extends upward and around the audience, removing many of those references. Give the image credible perspective, texture, shadows, and familiar architectural details, and the brain accepts the pixels as a room.

The same effect makes the Oz landscapes seem less like scenes displayed in front of the audience and more like places into which the auditorium has been inserted. Of course, there are more special effects. For The Wizard of Oz, there is wind and smoke, along with paper leaves, flower petals, and foam-rubber apples that fall from the sky. All of this makes it even more immersive.

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Get A Remote Terminal With One Binary, One URL, And Zero Config

August 3, 2026 by 20 Comments

Launch a single static binary executable, send someone a QR code or URL (or failing that, text a numerical code or shout it across a room), and they’ll get an encrypted terminal in their browser. No VPN, no port forwarding, no firewall modifications, and no account setup required. It’s BitBang by [Rich LeGrand], and there is a lot to go through in this one.

The best part? It’s not actually limited to just firing off a terminal. It’s a whole open framework for establishing an encrypted peer-to-peer connection between two systems over WebRTC without needing either a trusted central authority, or any special network configuration.

The signaling server brokers the handshake, then has no further involvement. By design, it couldn’t see application data even if it wanted to. Click to enlarge.

Opening a remote terminal, transferring files, or accessing web apps on a remote machine’s network is done with bitbang-cli, an implementation of BitBang focused on providing simple, zero-config remote access.

Before we go on, we want to mention that BitBang does require a lightweight, trustless signaling server only to broker the initial connection, but more on that in a moment.

On the machine to be shared, one first downloads the binary. Easiest way to do that is to go to bitba.ng and download manually, or copy and paste the one-line installer to auto-detect one’s system, download the correct release, and verify the checksum.

After the binary is downloaded, simply run it in a terminal and receive a QR code to scan, a URL to copy & paste, or a numerical code if those are inconvenient. On the remote side, one accesses the signaling server and the connection is made — one gets a terminal on the target machine open in the browser tab, with added options for file sharing and accessing web applications on the target network.

The signaling server isn’t involved in authentication or encryption, and couldn’t see private data between the two ends even if it wanted to. Prefer not to use someone else’s regardless? Run your own local instance with bitbang-server.

Originally developed as an easy way to securely make telepresence robots reachable over the Internet with nothing more than a QR code, today it’s a whole framework.

It includes not just the remote-access tool mentioned above, but also a BitBang Octoprint plugin for cloud-free remote access to 3D printers, and bitbang-python is a library for turning local Python web applications into a URL that can be opened from anywhere.

We’re sure some of you are getting more than a few ideas from this. If it lets you bring a project over the finish line, let us know on our tips line.