2026-01-20 00:30:16
Although arguably redundant on a typical computer keyboard, the idea of embedding small screens into the buttons on devices like audio production gear that often have so many buttons can make a lot of sense. As exemplified by devices with a UX that regularly degrades into scrolling through options on a tiny screen. This was basically the impetus for [Craig J Bishop] a few years ago to set out on a design project called the SoundSlab audio sequencer/sampler/synthesizer and slab that would make those buttons much more functional.
Obviously, the right way to start the project is to bulk buy hundreds of 0.85″ 128×128 LCDs so that you’re firmly locked into that choice. Fortunately, it turned out that the most annoying part of this LCD was the non-standard 0.7 mm pitch on its flat flex cable (FFC). This was worked around with an PCB adapter milled out of some copper-clad FR-1, which gave it a convenient PMOD interface for straightforward hook-up to a Xilinx Artix-7 FPGA board.
The buttons themselves were designed as 3D printed key caps for the LCDs that clipped onto typical Cherry MX-style mechanical keys. This also revealed that the original FFCs were too short, so they had to be replaced with new FFCs, that also adapted it to a standard 0.5 mm pitch. With this a 4×4 button prototype board could be constructed for testing.
Since that prototype [Craig] has built a full-sized SoundSlab grid, with a custom FPGA board and HDMI input, of which a preview can be seen in the post, along with a promise by [Craig] to soon post the rest of the SoundSlab development.
Thanks to [JohnS_AZ] for the tip.
2026-01-19 23:00:21
The Internet has spoiled us. You assume network packets either show up pretty quickly or they are never going to show up. Even if you are using WiFi in a crowded sports stadium or LTE on the side of a deserted highway, you probably either have no connection or a fairly robust, although perhaps intermittent, network. But it hasn’t always been that way. Radio networks, especially, used to be very hit or miss and, in some cases, still are.
Perhaps the least reliable network today is one connecting things in deep space. That’s why NASA has a keen interest in Delay Tolerant Networking (DTN). Note that this is the name of a protocol, not just a wish for a certain quality in your network. DTN has been around a while, seen real use, and is available for you to use, too.
Think about it. On Earth, a long ping time might be 400 ms, and most of that is in equipment, not physical distance. Add a geostationary orbital relay, and you get 600 ms to 800 ms. The moon? The delay is 1.3 sec. Mars? Somewhere between 3 min and 22 min, depending on how far away it is at the moment. Voyager 1? Nearly a two-day round trip. That’s latency!
So how do you network at these scales? NASA’s answer is DTN. It assumes the network will not be present, and when it is, it will be intermittent and slow to respond.
This is a big change from TCP. TCP assumes that if packets don’t show up, they are lost and does special algorithms to account for the usual cause of lost TCP packets: congestion. That means, typically, they wait longer and longer to retry. But if your packets are not going through because the receiver is behind a planet, this isn’t the right approach.
DTN nodes operate like a mesh. If you hear something, you may have to act as a relay point even if the message isn’t for you. Unlike most store-and-forward networks, though, a DTN node may store a message for hours or even days. Unlike most Earthbound network nodes, a DTN node may be moving. In fact, all of them might be moving. So you can’t depend on any given node being able to hear another node, even if they have heard each other in the past.
Is this new? Hardly. Email is store-and-forward, even if it doesn’t seem much like it these days. UUCP and Fidonet had the same basic ideas. If you are a ham radio operator with packet (AX.25) experience, you may see some similarities there, too. But DTN forms a modern and robust network for general purposes and not just a way to send particular types of messages or files.
While the underlying transport layer might use small packets — think TCP — DTN uses bundles, which are large self-contained messages with a good bit of metadata attached. Bundles don’t care if they move over TCP, UDP, or some wacky RF protocol. The metadata explains where the data is going, how urgent it is, and at what point you can just give up and discard it. The bundle’s header has other data, too, such as the length and whether the current bundle is just a fragment of a larger bundle. There are also flags forbidding the fragmentation of a bundle.
DTN isn’t just a theory. It has been used on the International Space Station and is likely to show up in future missions aimed at the moon and beyond.
But even better, DTN implementations exist and are available for anyone to use. NASA’s reference implementation is ION (Interplanetary Overlay Network), and it is made for NASA-level safety. It will, though, run on a Raspberry Pi. You can see a training video about ION and DTN in the video below.
There are some more community-minded implementations like DTN2 and DTN7. If you want to experiment, we’d suggest starting with DTN7. The video below can help you get started.
We hear you. As much as you might like to, you aren’t sending anything to Mars this week. But DTN is useful anywhere you have unreliable crummy networking. Disaster recovery? Low-power tracking transmitters that die until the sun hits their solar cells? Weak signal links in hostile terrain. All of these use cases could benefit from DTN.
We are always surprised that we don’t see more DTN in regular applications. It isn’t magic, and it doesn’t make radios defy the laws of physics. What it does is prevent your network from suffering fatally from those laws when the going gets tough.
Sure. You can do this all on your own. No NASA pun intended, but it isn’t rocket science. For specialized cases, you might even be able to do better. After all, UUCP dates back to the late 1970s and shares many of the same features. Remember UUCP schedules that determined when one machine would call another? DTN has contact plans that serve a similar purpose, except that instead of waiting for low long-distance rates, the contact plan is probably waiting for a predicted acquisition of signal time.
But otherwise? You knew UUCP wasn’t immediate. Routing decisions were often due to expectations of the future. Indefinite storage was all part of the system. Usenet, of course, rode on top of UUCP. So you could think of Usenet as almost a planetary-scale DTN network with messages instead of bundles.
A Usenet post might take days to show up at a remote site. It might arrive out of order, or twice. DTN has all of these same features. So while some would say DTN is the way of the future, at least in deep space networking, we would submit that DTN is a rediscovery of some very old techniques when networking on Earth was as tenuous as today’s space networks.
We’re sure that by modern standards, UUCP had some security flaws. DTN can suffer from some security issues, too. A rogue node can accept bundles and silently kill them, for example. Or flood the network with garbage bundles.
Then again, TCP DoS or man-in-the-middle attacks are possible, too. You simply have to be careful and think through what you are doing, if it is possible someone will attack your network.
So next time your project needs a rough-and-tumble network that survives even when you aren’t connected to the gigabit LAN, maybe try DTN. It has come a long way, literally and figuratively, since 2008. Well, actually, since 1997, as you can see in the video below. Whatever you come up with, be sure to send us a tip.
2026-01-19 20:00:00
Washington State’s House Bill 2321 is currently causing a bit of an uproar, as it seeks to add blocking technologies to 3D printers, in order to prevent them from printing “a firearm or illegal firearm parts”, as per the full text. Sponsored by a sizeable number of House members, it’s currently in committee, so the likelihood of it being put to a floor vote in the House is still remote, never mind it passing the Senate. Regardless, it is another chapter in the story of homemade firearms, which increasingly focuses on private 3D printers.
Also called ‘ghost guns‘ in the US, these can be assembled from spare parts, from kits, from home-made components, or a combination of these. While the most important parts of a firearm – like the barrel – have to be made out of something like metal, the rest can feature significant amounts of (3D printed) plastic parts, though the exact amount varies wildly among current 3D-printed weapons.
Since legally the receiver and frame are considered to be ‘firearms’, these are the focus of this proposed bill, which covers both additive (FDM, SLA, etc.) and subtractive (e.g. CNC mill) technology. The proposal is that a special firearms detection algorithm has to give the okay for the design files to be passed on to the machine.
This blocking feature would have to be standard for all machines sold or transferred in the state, with a special ‘preprint authentication’ handshake protocol required. The attorney general is here expected to create and maintain a database of the no longer legal firearm and parts designs for those without a requisite license.
Putting aside for a moment the ridiculousness of implementing such a scanning feature, even if it wouldn’t be child’s play to circumvent with e.g a compatible SBC and fresh copy of Klipper or the equivalent for any CNC mill, it also barks up the wrong tree. Although in the most recent ruling pertaining to this topic in Bondi v. VanDerStok it was acknowledged that advances in 3D printing have made this worth considering from a legislative context, the main issue with ‘ghost guns’ comes still by far from kits and similar sources.
Based on this, it seems highly unlikely that HB 2321 will be put up for a vote, never mind get signed into law. Although 3D printed designs like the 9×19 mm cartridge Urutau bullpup are apparently quite functional, it’s notable that its manufacturing involves many steps, many DIY store parts and a bolt carrier manufactured from steel bar stock, not to mention a significant time investment. Trying to detect ‘firearm parts’ at any of these steps would seem to be a fool’s errand, even if privacy considerations were not an issue.
2026-01-19 17:00:00
Famously, the save icon on most computer user interfaces references a fairly obsolete piece of technology: the venerable floppy disk. It’s likely that most people below the age of about 30 have never interacted with one of these once-ubiquitous storage devices, so much so that many don’t recognize the object within the save icon itself anymore. [Mads Chr. Olesen]’s kids might be an exception here, though, as he’s built a remote control for them that uses real floppy disks to select the programming on the TV.
This project partially began as a way to keep the children from turning into zombies as a result of the modern auto-play brainrot-based economies common in modern media. He wanted his kids to be able to make meaningful choices and then not get sucked into these types of systems. The floppy disk presents a perfect solution here. They’re tangible media and can actually store data, so he got to work interfacing a real floppy disk drive with a microcontroller. When a disk is inserted the microcontroller wakes up, reads the data, and then sends out a command to stream the relevant media to the Chromecast on the TV. When the disk is removed, the microcontroller stops play.
Like any remote, this one is battery powered as well, but running a microcontroller and floppy disk drive came with a few challenges. This one is powered by 18650 lithium cells to help with current peaks from the drive, and after working out a few kinks it works perfectly for [Mads] children. We’ve seen a few other floppy disk-based remote controls like this one which replaces the data stored on the magnetic disc with an RFID tag instead.
2026-01-19 14:00:59
Over on YouTube [Kiss Analog] reviews the New Zoyi ZT-QB9 Smart Clamp meter.
If you’re putting together an electronics lab from scratch you absolutely must get a multimeter to start. A typical multimeter will be able to do current measurements but it will require you to break the circuit you’re measuring and interface it to your meter using its mechanical probes.
A good choice for your second, or third, multimeter is a clamp-based one. Many of the clamp meters have the clamp probe available for current measurements while still allowing you to use the standard 4mm banana jack probes for other measurements, particularly voltage and resistance.
If you’re curious to know more about how clamp meters work the answer is that they rely on some physics called the Hall Effect, as explained by the good people at Fluke.
In the video the following clamp meters are seen: Zoyi ZT-QB9, PROVA 11, and Hioki CM4375. If you’re in the market for a clamp meter you might also like to consider the EEVblog BM036 or a clamp meter from Fluke.
We have of course posted about clamp meters before. Check out Frnisi DMC-100: A Clamp Meter Worth Cracking Open or ESP32 Powers DIY Smart Energy Meter if you’d like to know more. Have your own trusty clamp meter? Don’t need no stinkin’ clamp meter? Let us know in the comments!
2026-01-19 11:00:59
For switching high-powered loads from a microcontroller, or for switching AC loads in general, most of us will reach into the parts bin and pull out a generic relay of some sort. Relays are fundamental, proven technologies to safely switch all kinds of loads. They do have their downsides, though, so if you need silent operation, precise timing, or the ability to operate orders of magnitude more times you might want to look at a triac instead. These solid state devices can switch AC loads unlike other transistor-based devices and [Ray] at OpenSprinkler is here to give us an overview on how to use them.
The key to switching an AC load is bi-directional conductivity. A normal transistor or diode can only conduct in one direction, so if you try to switch an AC load with one of these you’ll end up with what essentially amounts to a bad rectifier. Triacs do have a “gate” analogous to the base of a bipolar junction transistor, but the gate will trigger the triac when current flows in either direction as well. The amount of current needed to trigger the triac does depend on the state of the switched waveform, so it can be more complex to configure than a relay or transistor in some situations.
After going through some of the theory around these devices, [Ray] demonstrates how to use them with an irrigation system, which are almost always operating on a 24VAC system thanks to various historical quirks. This involves providing the triacs with a low voltage source to provide gate current as well as a few other steps. But with that out of the way, switching AC loads with triacs can become second nature. If you prefer a DC setup for your sprinklers, though, [vinthewrench] has demonstrated how to convert these sprinkler systems instead.
