This week, Hackaday’s Elliot Williams and Kristina Panos met up over coffee to bring you the latest news, mystery sound, and of course, a big bunch of hacks from the previous seven days or so.
On What’s That Sound, Kristina got sort of close, but of course failed spectacularly. Will you fare better and perhaps win a Hackaday Podcast t-shirt? Mayhap you will.
After that, it’s on to the hacks and such, beginning with an interesting tack to take with a flat-Earther that involves two gyroscopes. And we take a look at the design requirements when it comes to building synths for three-year-olds.
Then we discuss several awesome hacks such as a vehicle retrofit to add physical heated seat controls, an assistive radio that speaks the frequencies, and an acoustic radiometer build. Finally, we look at the joys of hacking an old Kindle, and get a handle on disappearing door handles.
Check out the links below if you want to follow along, and as always, tell us what you think about this episode in the comments!
Download in DRM-free MP3 and savor at your leisure.
The Digital-Technik 2075 comes with a few components including a battery holder and 9 V battery, a push button, two 1 K resistors, a red LED, a 100 nF ceramic capacitor, a 100 µF electrolytic capacitor, a quad NAND gate IC, and a counter module which includes an IC and a 7-segment display. The kit also comes with wires, plugs, a breadboard, and a tool for extracting modules.
The Digital-Technik 2075 doesn’t use the spring terminals we see in other project labs of the time, such as the Science Fair kits from Radio Shack, and it doesn’t use modular Denshi blocks, such as we saw from the Gakken EX-150, but rather uses wire in conjunction with yellow plastic plugs. This seems to work well enough.
In the video, after showing us how to do switch debouncing, [Jason] runs us through making a counter with the digital components and then getting the counter to reset after it counts to five. This is done using NAND gates. Before he gets stuck into doing a project he takes a close look at the manual (which is in German) including some of the advertisements for other project labs from Busch which were available at the time. As he doesn’t speak German [Jason] prints out an English translation of the manual before working through it.
We’ve heard from [Jason] at Hackaday in recent history when we saw his Microtronic Phoenix Computer System which referenced the 2090 Microtronic Computer System which was also made by Busch.
The BBC wanted to show everyone how a computer might be used in schools. A program aired in 1979 asks, “Will Computers Revolutionise Education?” There’s vintage hardware and an appearance of PILOT, made for computer instructions.
Using PILOT looks suspiciously like working with a modern chatbot without as much AI noise. The French teacher in the video likes that schoolboys were practicing their French verb conjugation on the computer instead of playing football.
If you want a better look at hardware, around the five-minute mark, you see schoolkids making printed circuit boards, and some truly vintage oscilloscope close-ups. There are plenty of tiny monitors and large, noisy printing terminals.
You have to wonder where the eight-year-olds who learned about computers in the video are today, and what kind of computer they have. They learned binary and the Towers of Hanoi. Their teacher said the kids now knew more about computers than their parents did.
As a future prediction, [James Bellini] did pretty well. Like many forecasters, he almost didn’t go far enough, as we look back almost 50 years. Sure, Prestel didn’t work out as well as they thought, dying in 1994. But he shouldn’t feel bad. Predicting the future is tough. Unless, of course, you are [Arthur C. Clarke].
Algorithms? Datamining? Brainrot? You don’t need those things to have a social network. As we knew back in the BBS days, long before anyone coined the phrase “social network”, all you need is a place for people to make text posts. [euklides] is providing just such a place, at cyberspace.online.
It’s a great mix of old and new — the IRC inspired chatrooms, e-mail inspired DMs (“cybermail”) make it feel like the good old days, while a sprinkling of more modern concepts such as friends lists, a real-time feed, and even the late-lamented “poke” feature (from before Facebook took over the world) provide some welcome conveniences.
The pursuit of retro goes further through the themed web interface, as well. Sure, there’s light mode and dark mode, but that’s de rigueur. Threads might not offer a blue-and-white Commodore 64 theme, and you’d have little luck getting Bluesky to mimic the soothing amber glow of a VT-230, but Cyberspace offers that and more.
This is very much a das blinkenlights kind of project. The goal is to get a 7-segment display to count from 0 to 9, and that’s it. [Gerry] has a 74LS193 Up/Down Binary Counter, a 74LS42 BCD to Decimal Decoder, and some 74LS00 NAND gates, but he “doesn’t have” an 74LS48 to drive the 7-segment display so he emulates one with an old Altera CPLD model EPM7064SLC44 which dates back to the late nineties. A CPLD is a Complex Programmable Logic Device which is a kind of precursor to FPGA technology.
The eccentric shaft and rotor of the Mazda 12A rotary engine. (Credit: Baked Beans Garage, YouTube)
In theory, Wankel-style rotary internal combustion engines have many advantages: they ditch the cumbersome crankcase and piston design, replacing it with a simple, single-chamber design and a thick, plectrum-shaped chunk of metal that spins around inside that chamber to create virtual combustion chambers. This saves weight and maximizes performance-to-weight. Unfortunately, these types of engines are also known for burning a lot of oil and endless seal troubles, especially with early rotary Mazda engines that easily died.
Yet even 1980 versions were not without issues, a case in point is the Mazda 1st gen RX7 with a 12A rotary engine that the [Baked Beans Garage] over at YouTube got their paws on. Starting with unsuccessful attempts to make the car start, the next step was to roll the car into the morgue garage for a full teardown of the clearly deceased engine.
About 35 minutes into the video, we get to the teardown of the engine, with its parts contrasted with those of a newer revision rotary engines alongside illustrations of their functioning, making it as much an autopsy as a detailed introduction to these rotary engines. Technically, they also aren’t the original DKM-style Wankel engines, but a KKM-style engine, as designed by [Hanns-Dieter Paschke]. [Wankel] didn’t like the eccentric KKM design, as he thought it’d put too much stress on the apex seals, but ultimately the more economical KKM design was further developed.
During the autopsy of the 12A revision Mazda engine, it becomes clear that it was likely overheating that killed the engine over the course of years of abuse, along with ‘chatter’ marks of the apex seals destroying the inner chrome coating. This would have compromised compression and with it any chance of the engine running, not unlike a piston engine with badly scored cylinder walls after ingesting some metal chunks.
While the Mazda 12B and subsequent designs addressed many of the issues with the early rotary engines, its use was limited to some sports models, ending in 2012 with the RX-8. The currently produced Mazda MX-30 does use a rotary engine again in its plug-in hybrid version, but it’s only as a range extender engine that drives a generator. Looking at the internals of those Mazda rotary engines, it’s easy to see how complex they are to keep running, but you cannot help but feel a little bit of sadness that these small-but-powerful engines didn’t make much more of a splash.
When you go on your favorite cheap online shopping platform and order a batch of 74LS logic ICs, what do you get? Most likely relabeled 74HC ICs, if the results of an AliExpress order by [More Fun Fixing It] on YouTube are anything to judge by. Despite the claims made by the somewhat suspect markings on the ICs, even the cheap component tester used immediately identified them as 74HC parts.
Why is this a problem, you might ask? Simply put, 74LS are Low-power Schottky chips using TTL logic levels, whereas 74HC are High-Speed CMOS, using CMOS logic levels. If these faked chips had used 74HCT, they would have been compatible with TTL logic levels, but with the TTL vs CMOS levels mismatch of 74HC, you are asking for trouble.
CMOS typically requires that high levels are at least 70% of Vcc, and low to be at most 30% of Vcc, whereas TTL high level is somewhere above 2.0V. 74HC also cannot drive its outputs as strongly as 74LS, which opens another can of potential issues. Meanwhile HCT can be substituted for LS, but with the same lower drive current, which may or may not be an issue.
Interestingly, when the AliExpress seller was contacted with these findings, a refund was issued practically immediately. This makes one wonder why exactly faked 74LS ICs are even being sold, when they’d most likely be stuffed into old home computers by presumably hardware enthusiasts with a modicum of skill and knowledge.
![[Gerry] holding up a DIP IC](https://hackaday.com/wp-content/uploads/2025/11/Behind-The-Code-with-Gerry-Altera-CPLD-banner.jpg?w=600&h=450)
