2026-03-22 13:00:19
We have to admit, we didn’t know that we wanted a desktop electric jellyfish until seeing [likeablob]’s Denki-Kurage, but it’s one of those projects that just fills a need so perfectly. The need being, of course, to have a Bladerunner-inspired electric animal on your desk, as well as having a great simple application for that Cheap Yellow Display (CYD) that you impulse purchased two years ago.
Maybe we’re projecting a little bit, but you should absolutely check this project out if you’re interested in doing anything with one of the CYDs. They are a perfect little experimentation platform, with a touchscreen, an ESP32, USB, and an SD card socket: everything you need to build a fun desktop control panel project that speaks either Bluetooth or WiFi.
We love [likeablob]’s aesthetic here. The wireframe graphics, the retro-cyber fonts in the configuration mode, and even the ability to change the strength of the current that the electric jellyfish is swimming against make this look so cool. And the build couldn’t be much simpler either. Flash the code using an online web flasher, 3D print out the understated frame, screw the CYD in, et voila! Here’s a direct GitHub link if you’re interested in the wireframe graphics routines.
We’ve seen a bunch of other projects with the CYD, mostly of the obvious control-panel variety. But while we’re all for functionality, it’s nice to see some frivolity as well. Have you made a CYD project lately? Let us know!
2026-03-22 10:00:41
Although the CRT has largely disappeared from our everyday lives, there was a decades-long timeframe when this was effectively the only display available. It’s an analog display for an analog world, and now that almost everything electronic is digital, these amazing pieces of technology are largely relegated to retro gaming and a few other niche uses. [Maurycy] has a unique CRT that’s small enough to fit in a handheld television, but since there aren’t analog TV stations anymore, he decided to build his own with nothing but an 8-bit microcontroller and a few other small parts.
The microcontroller in question is a fairly standard 8-bit AVR. These microcontrollers have one major limitation when generating the VHF and UHF radio signals needed for analog TV: their natural clock speed is much too low. The maximum output frequency of a pin on this microcontroller is only 6 MHz, and [Maurycy] needs something about two orders of magnitude faster. To solve this problem, [Maurycy] uses a quirk of the square wave generated by toggling a pin at its maximum frequency, which is that a wide range of harmonics will be generated, some of which will have a high enough frequency to be picked up on the handheld analog TV. The microcontroller is configured to use two pins. Toggling the pins into various states allows the humble AVR to generate a usable TV signal.
The scan rate for CRTs is comparably low as well. At the beginning of each frame, there’s enough processing power left on the microcontroller to play Conway’s Game of Life, which is then sent out over the airwaves to the TV. [Maurycy] notes that his harmonics-based video generation method is extremely noisy and probably wouldn’t pass FCC muster. However, the signal Power is so low that it’s unlikely to interfere with anything. If you’re curious about these unusual sideways-built CRTs, though, we recently saw someone take two apart and use them to build a CRT-based VR headset.
2026-03-22 07:00:20
The best part about retro computing is the idea that you’ll save some poor system from being scrapped and revive it to a working state, at which point you can bask in the glory of a job well done. That’s when reality often strikes hard, and you find yourself troubleshooting a maddening list of issues as you question everything about your life choices. Such was the case with [This Does Not Compute] over at YouTube with a Sun SPARCstation IPX that decided to put up a big fight.
This is the second video of a series. In the first installment, the PSU was repaired, and a boot failure was diagnosed. The system’s onboard diagnostic led to the assumption that one of the 8 kB SRAM ICs was defective. You can readily get SRAM replacements, so it seemed to be an easy fix. Unfortunately, the fun was only beginning as the system reported the exact same error after the SRAM was replaced.
After flipping a virtual table, the mainboard was swapped with a donor one from a scrapped laptop system. With this, it booted, but the video output showed only vertical lines. Obviously, the solution here was to insert a replacement video card, which not only fixed the display output but also demonstrates once again that you can fix many vintage computing issues by simply replacing hardware.
With the system now seemingly happy, a disk drive was added so that Solaris 2.3 could be installed. This turned into another confusing job. Getting into the GUI was seemingly impossible. Ergo, this virtual table got flipped, too, and Solaris 2.6 was installed. Finally, the system got to the desktop GUI. At this point it was clear that this 40 MHz mid-range SPARCstation from 1991 is no speed monster. Just drawing windows was slower than an X11 remote session over 9600 baud dial-up.
Installing more RAM might have helped here, but the system requires parity FP RAM, which could have been purchased, but at some point, you have to decide how much money you want to throw at an old system like this. Although these are still pretty interesting systems in their own right, it should be clear that they are not easy systems to repair or maintain.
2026-03-22 04:00:44
We’re used to electronic parts of the same type staying predictably the same, sometimes over many years. An early Z80 from the mid 1970s can be exchanged with one from the end of production a few years ago, for example. This week, we’ve had DMs from several readers who’ve found that this is not always the case, and the culprit is surprising. Espressif has released a new revision of their P4 application processor, and though it’s ostensibly the same, there are a couple of changes that have been catching people out.
The changes lie in both hardware and software, in that there’s a pin that’s changed from NC to a power rail, a few extra passives are needed, and firmware must be compiled separately for either revision. The problem is that they are being sold as the same device and appear in some places under the same SKU! This is leading to uncertainty as to which P4 revision is in stock at wholesalers. We’ve been told about boards designed for the old revision being assembled with the new one, a situation difficult to rework your way out of. Designers are also left uncertain as to which firmware build is needed for boards assembled in remote factories.
The ESP32-P4 is an impressive part for its price, and we’re sure that we’ll be seeing plenty of projects using this new revision over the coming years. We’re surprised that it doesn’t have a different enough part number and that the wholesalers have seemingly been caught napping by the change. We’re told that some of the well-known Chinese assembly houses are now carrying the two chips as separate SKUs, but that’s scant consolation for a designer with a pile of boards carrying the wrong part. If you’re working with the P4, watch out, make sure your board is designed for the latest revision, and ask your supplier to check which chips you’ll get.
If the P4 is new to you, we’ve already seen a few projects using it.
2026-03-22 01:00:00
For better or worse, there are a few instruments that have been pigeonholed into specific genres of popular music. For example, banjos are often heard in bluegrass or folk, harmonicas in blues, and a sick horn section will take many of us immediately to third wave ska. Similarly, there are certain styles of synthesizers tied to various genres and if you’re a fan a certain sub-genre of reggae you’ll be familiar with the dub siren. This unique analog synth has a few tricks up its sleeve and [Jakub] shows us how he built his.
He’s calling this build the Sirenotron, and its based on the venerable 555 timer It also features an LFO built on an LM358, with triangle and square wave modes, plus an additional “acid mode” for the square wave which adds a single capacitor to the circuit but makes a big difference in the sound. Like any siren synth, there are potentiometers to control pitch and the pulse rate of the siren as well and another switch controls whether it is outputting sound or not. He’s also included the ability to control it with a foot pedal so he can use it while playing the bass guitar during live shows.
[Jakub] has gone through several prototypes before getting to this stage, and not only uses it when playing dub but also creates psychedelic soundscapes in a side project of his where it also fits right in. He’s also made the schematics available for anyone who wants to reproduce it or build on his design.
We’re always interested in a unique synthesizer build around here, and some of our favorites include this synth built from Sega Genesis parts and this one controlled more like a woodwind instrument.
2026-03-21 22:00:31
We’re all used to it by now, but I’d just like to reflect on how insanely power-packed lithium ion batteries are, and everything that’s afforded us. I’m trying to think of a gadget, a hobby, or nearly anything in my house that’s not touched by the battery chemistry.
I’m looking at my portable wireless keyboard in front of me, with a LiPo pack inside. Oddly enough, I’m charging it with a LiPo-based power bank, simply because the cable to the nearest USB-C adapter is too short. A gaming console, cell phone, and a DSLR camera are all within arms reach and powered with lithium.
It’s not just consumer stuff either. I fly FPV quads and airplanes for fun when I can, and of course those are made entirely possible by the combination of smaller brushless DC motors and their drivers, and the high-power-density LiPo packs that power them. For field recharging, I have a huge self-made LiIon pack that can keep them all in the air all day. These days, LiPo and LiIon tech is the heart of hacker projects big and small. Heck, we even powered this year’s Hackaday Supercon badge with a LiPo that allowed it to run all weekend on a charge for many folks, where in the past swapping out AAs during the event was commonplace.
The application that still blows my mind is that we recently got a solar installation on our roof, which means a huge LiFePo battery in the basement. And while it’s one thing to power noisy little quads on the battery tech, it somehow seems another to power our entire house, for multiple hours per day, from a battery. Granted it’s not a couple of AAA cells in a little black plastic box, but it’s simply amazing to run a washing machine, the fridge, the stove, and even the heating off of what amounts to a battery pack.
Of course, I’m aware of the costs of producing the cells, both in terms of money and the environmental damage. It’s not a free lunch, and I’m looking forward to both cleaner and cheaper energy storage chemistries in the future. But for now, I’m still in awe of the many options that lithium-based battery chemistry has brought us. May your pillows remain non-spicy!
