The thermite process is a handy way to generate molten iron in the field. It’s the reaction between aluminium metal and iron oxide, which results in aluminium oxide and metallic iron. It’s hot enough that the iron is produced as a liquid, which means it’s most notably used for in-field welding of things such as railway tracks. All this is grist to [Cody’s Lab]’s mill of course, so in the video below the break he attempts to use a thermite reaction in a rough-and-ready foundry, to make a cast-iron frying pan.

Most of the video deals with the construction of the reaction vessel and the mold, for which he makes his own sodium silicate and cures it with carbon dioxide. The thermite mix itself comes from aluminium foil and black iron oxide sand, plus some crushed up drinks cans for good measure.

The result is pretty successful at making a respectable quantity of iron, and his pour goes well enough to make a recognizable frying pan. It has a few bubbles and a slight leak, but it’s good enough to cook an egg. We’re sure his next try will be better. Meanwhile this may produce a purer result, but it’s by no means the only way to produce molten iron on a small scale.

[Adam Francis] bought some cheap speaker drivers from AliExpress. Are they any good? Difficult to tell without a set of enclosures for them, so he made a set of transmission line cabinets. The resulting video proves that a decent sounding set of speakers shouldn’t have to cost the earth, and is quite entertaining to watch.

The design he’s going for is a transmission line, in effect a folded half-wave resonant tube terminated at one end and open at the other, with the speaker close to half way along. There is a lot of nuance to perfecting a speaker cabinet, but this basic recipe doesn’t have to be optimum to give a good result.

So after having some MDF cut to shape and glueing it all together, he ends up with some semi decent speakers for not a lot of money. The video is entertaining, with plenty of Britishisms, but the underlying project is sound. We’d have a pair on our bench.

A tuned circuit formed by a capacitor and an inductor is a familiar enough circuit, and it’s understood that it will resonate at a particular frequency. As that frequency increases, so the size of the capacitor and inductor decrease, and there comes a point at which they can become the characteristic capacitance and inductance of a transmission line. These tuned circuits can be placed in an enclosure, at which they can be designed for an extremely high Q factor, a measure of quality, and thus a very narrow resonant point. They are frequently used as filters for that reason, and [Fesz] is here with a video explaining some of their operation and configurations.

Some of the mathematics behind RF design can be enough to faze any engineer, but he manages to steer a path away from that rabbit hole and explain cavity filters in a way that’s very accessible. We learn how to look at tuned circuits as transmission lines, and the properties of the various different coupling methods. Above all it reveals that making tuned cavities is within reach.

They’re a little rare these days, but there was a time when almost every TV set contained a set of these cavities which were ready-made for experimentation.

Years ago there was a sharp divide in desktop computing between the mundane PC-type machines, and the so-called workstations which were the UNIX powerhouses of the day. A lot of familiar names produced these high-end systems, including the king of the minicomputer world, DEC. The late-80s version of their DECstation line had a MIPS processor, and ran ULTRIX and DECWindows, their versions of UNIX and X respectively. When we used one back in the day it was a very high-end machine, but now as [rscott2049] shows us, it can be emulated on an RP2040 microcontroller.

On the business card sized board is an RP2040, 32 MB of PSRAM, an Ethernet interface, and a VGA socket. The keyboard and mouse are USB. It drives a monochrome screen at 1024 x 864 pixels, which would have been quite something over three decades ago.

It’s difficult to communicate how powerful a machine like this felt back in the very early 1990s, when by today’s standards it seems laughably low-spec. It’s worth remembering though that the software of the day was much less demanding and lacking in bloat. We’d be interested to see whether this could be used as an X server to display a more up-to-date application on another machine, for at least an illusion of a modern web browser loading Hackaday on DECWindows.

Full details of the project can be found in its GitHub repository.

LCD televisions are a technological miracle, but if they have an annoying side it’s that some of them are a bit lacklustre when it comes to displaying black. [Mousa] has a solution, involving a small LCD and a bit of lateral thinking.

These screens work by the LCD panel being placed in front of a bright backlight, and only letting light through at bright parts of the picture. Since LCD isn’t a perfect attenuator, some of the light can make its way through, resulting in those less than perfect blacks. More recent screens replace the bright white backlight with an array of LEDs that light up with the image, but the electronics to make that happen are not exactly trivial.

The solution? Find a small LCD panel and feed it from the same HDMI source as a big panel. Then place an array of LDRs on the front of the small LCD, driving an array of white LEDs through transistor drivers to make a new responsive backlight. We’re not sure we’d go to all this trouble, but it certainly looks quite cool as you can see below the break.

This may be the first responsive backlight we’ve brought you, but more than one Ambilight clone has graced these pages.

At Hackaday, we comb the world of tech in search of good things to bring you. Today’s search brought up something very familiar, [Jazzy Jane] has an Advance E1 tube signal generator, the same model as the unit on the shelf above where this is being written. It’s new to her, so she’s giving it a teardown and fixing any safety issues before powering it on.

For a 70+ year old unit, the quality of these instruments was such that they remain useful and reliable to this day. Unsurprisingly a few things need looking at, such as an aged mains lead and a pair of filter caps in the power supply which haven’t aged well. These parts failed on the E1 here too, and while she’s taking the time to order appropriate replacements we have to admit to being cheapskates and robbing parts with an appropriate working voltage for ours from a nearby PC power supply.

Where this one becomes rather interesting is in an extra switch and socket. It’s a wafer switch with a load of capacitors, and the best guess is it provides some adjustability for the inbuilt audio oscillator which had a fixed frequency on stock models. This is part one of a series though, so we’re looking forward to finding out its purpose in the next installment. Take a look at the video below the break, and if that’s not enough, we seem to have had more than one piece of vintage British test equipment here of late.

In the monthly Ladybird Browser update video which we’ve placed below, SerenityOS founder [Andreas Kling] announced an interesting development. The browser has been forked from the OS that has been its progenitor, and both projects will now proceed separately. This frees the browser from the SerenityOS insistence on avoiding external libraries, and allows it to take advantage of stable, fast, and mature open source alternatives. This is already paying dividends in compatibility and speed, and is likely to lead further towards a usable everyday browser as time goes by.

As the world of fully-featured web browser engines has contracted from a number of different projects to little more than Google’s Blink and Mozilla’s Gecko, Ladybird has found itself in an unexpected position. It is vital that the browser market retains some competition and does not become a Google monoculture, so while it might not seem so at first glance, the news of Ladybird going alone has the potential to be one of the most far-reaching open source stories of the year.

If you’d like to try Ladybird you’ll have to get your hands slightly dirty and build it yourself, but we’d expect ready-built versions to appear in due course. We took a look at an earlier version of Ladybird last year, as well as SerenityOS itself.

In the days before integrated circuits became ubiquitous, providing advanced functionality in a single package, designers became adept at extracting the maximum use from discrete components. They’d use clever circuits in which a transistor or other active part would fulfill multiple roles at once, and often such circuits would need more than a little know-how to get working. It’s not often in 2024 that we encounter this style of circuit, but here’s [Maurycy] with a cheap microwave radar module doing just that.

On the board is an RF portion with a single transistor, some striplines, and an SOIC chip. Oddly this last part turns out to be an infra-red proximity sensor chip, so what’s going on? Careful analysis of the RF circuit reveals something clever. As expected, it’s a 3.18 GHz oscillator, but how is it functioning as both transmitter and receiver? The answer comes in the form of a resistor and capacitor in the emitter circuit, which causes the transistor to also oscillate at about 20 kHz. The result is that at different times in the 20 kHz period, the transistor is either off, fully oscillating at 3.18GHz and transmitting, or briefly in the not-quite-oscillating state between the two during which it functions as a super-regenerative receiver. This is enough for one device to effectively transmit and receive at the same time with the minimum of parts, there’s no need for a mixer diode as you might expect if it were it a direct conversion receiver. Perhaps in RF terms, it’s not particularly pretty, but we have to admit to being impressed by its simplicity. He goes on to perform a few experiments with the board as a transmitter or as a more conventional radar.

This isn’t the first such radar module we’ve looked at, here’s one designed from scratch. And we love regens, since they are so simple to build.

There’s a mystique in old keyboard circles around the IBM Model M, the granddaddy of PC keyboards with those famous buckling spring key switches. The original Model M was a substantial affair with a sheet metal backplane that would probably serve well as a weapon in a zombie apocalypse and still allow writing a Hackaday piece afterward, but later on in the life of these ‘boards there was also a lighter version. The M2 as these models are dubbed has a few known problems, and [Anders Nielsen] scored one online that turned out to have dodgy capacitors. His video, below the break, takes us through the disassembly of his M2 and provides a relaxing tour of these not-quite-so-famous peripherals.

As you’d expect, three-decade-old plastic isn’t always in the best shape, so disassembly and unlatching all those little tabs has to be performed with care. The keys come off and the springs are on show, but we get a nasty shock when they all fall out of place as the top is removed. It appears the rookie mistake is to not turn the ‘board upside down before parting it. Replacing the caps is an easy process after all that, and we get a little dive into the 6805 processors used in model Ms.

If you have a model M of any description then you’re probably at home with the clack-clack-clack sound they make, but have you ever looked at its ancestor, the model F?

If you ever encounter a British engineer of a certain age, the chances are that even if they use a modern DMM they’ll have a big boxy multimeter in their possession. This is the famous Avo 8, in its day the analogue multimeter to have. Of course it wasn’t the only AVO product, and [Thomas Scherrer OZ2CPU] is here with another black box sporting an AVO logo. This one’s an AC bridge, one of a series of models manufactured from the 1930s through to the late 1940s, and he treats us to a teardown and restoration of it.

Most readers will probably be familiar with the operation of a DC Wheatstone Bridge in which two resistances can be compared, and an AC bridge is the same idea but using an AC source. A component under test is attached to one set of terminals while one with a known value is put on the other, and the device can then be adjusted for a minimum reading on its meter to achieve a state of balance. The amount by which it is adjusted can then be used as a measure of the difference between the two parts, and thus the value of an unknown part can be deduced.

In the case of this AVO the AC is the 50Hz (remembering that this is a British instrument) mains frequency, and the reading from the bridge is taken via a single tube amplifier to a rectifier circuit and the meter. Inside it’s a treasure trove of vintage parts with an electrolytic capacitor that looks as though it might not be original, with a selenium rectifier and a copper oxide signal diode in particular catching our eye. This last part is responsible for some reading anomalies, but after cleaning and lubricating all the switches and bringing up the voltage gently, he’s rewarded with a working bridge. You can see the whole story in the video below the break.

Test equipment from this era is huge, so perhaps not all of you have the space for something like this. Some of us have been known to own other AVO products though.

Fusion power has long held the promise of delivering near-endless energy without as many unfortunate side effects as nuclear fission. But despite huge investment and some fascinating science, the old adage about practical power generation being 20 years away seems just as true as ever. But is that really the case? [Brian Potter] has written a review article for Construction Physics, which takes us through the decades of fusion research.

For a start, it’s fascinating to learn about the many historical fusion process, the magnetic pinch, the stelarator, and finally the basis of many modern reactors, the tokamak. He demonstrates that we’ve made an impressive amount of progress, but at the same time warns against misleading comparisons. There’s a graph comparing fusion progress with Moore’s Law that he debunks, but he ends on a positive note. Who knows, we might not need a Mr. Fusion to arrive from the future after all!

Fusion reactors are surprisingly easy to make, assuming you don’t mind putting far more energy in than you’d ever receive in return. We’ve featured more than one Farnsworth fusor over the years.

There’s a pleasing retro analogue experience to shooting Super 8 film, giving as it does the feel of a 1970s home movie to your work. But once you’ve had the film developed, there’s a need for a projector to enjoy the result. Far better to digitize it for a more modern viewing and editing experience. [Elbert] has made a digitizer for 8mm film which takes the best approach, snapping each frame individually to be joined together in a video file as a whole.

The frame of the device is 3D printed, but some parts of a film transport must be higher quality than a printed part can deliver. These, in particular the sprockets, are salvaged from a film viewer, and the movement is powered by a set of stepper motors. The steppers are controlled by an ESP32, and the optics are provided by a USB microscope. All this is hooked up to a PC which grabs each image, and finally stitches them all together using ffmpeg.

As anyone who has dabbled in 8mm film will tell you, there is a lot in the quality of a film digitizer, and it’s often worth paying for a professional job from someone aimed at the film-making world rather than you local photographic print booth. It would be interesting to take a look at this device, and see whether its quality is worth pursuing. After all, some of us have been known to dabble in 8mm film.

Now the eyes of space explorers are turned once more towards the Moon, there are a whole host of new engineering challenges facing engineers working on lunar missions. One such challenge relates to how any proposed Moon base might be built, and as European Space Agency (ESA) researchers turn their mind to the problem they’ve taken a uniquely European approach. They’ve made some LEGO bricks.

Sadly lunar regolith is in short supply in Europe at the moment, so as a stand-in they’ve ground up a meteorite, mixed the powder with a polymer, and 3D printed their bricks. The LEGO write-up is a little long on frothy writing style and a little short on the science, but it seems that they clutch in exactly the same way as the official bricks from Billund, and can be assembled just as you would a normal set of bricks.

It’s with some regret that we have to concede that Europe’s off-planet outpost won’t be crewed by LEGO people in a base made from LEGO bricks, but we applaud them for doing this as a practical test given the limited supply of starter material. LEGO themselves have snagged some of them to display in a range of their flagship stores, so we hot-footed it down to London to catch some pictures. What we found is a single brick in a glass case, sadly looking very like any other 3D printed brick in a shiny grey medium. It’s probably the most expensive brick in the world though, so we doubt they’ll be available to buy any time soon.

If you’re hungry for more of all things LEGO, we can do no better than suggest a trip to the mother lode, in Billund, Denmark.

If you don’t happen to have a traditional stone-floored domed clay oven on hand, it can be surprisingly challenging to make a pizza that’s truly excellent. Your domestic oven does a reasonable job, but doesn’t really get hot enough. Even a specialist pizza oven such as [Yvo de Haas]’ Ooni doesn’t quite do the best possible, so he’s upgraded it with the SpinMeister — a system for precise timing of the heat, and controlled rotation of the cooking stone for an even result.

The spinning part is handled by a stepper motor, driving a hex shaft attached to the bottom of the stone through a chuck. The rotating bearing itself is from an aftermarket stone rotator kit. The controller meanwhile is a smart 3D printed unit with a vacuum-fluorescent display module, powered from an Arduino Nano. There’s a motor controller to handle driving the stepper, and an MP3 module for audible warning. It’s all powered from a USB-C powerbank, for true portability. He’s produced a video showing it cooking a rather tasty-looking flatbread, which we’ve placed below. Now for some unaccountable reason, we want pizza.

If you recognize [Yvo]’s name, then perhaps it’s because he’s appeared on these pages a few times. Whether it’s a tentacle robot or something genuinely different in 3D printing, his work never ceases to be interesting.

Sometimes it’s the most straightforward of hacks which are also the most satisfying, and so it is that we’d like to draw your attention to [mikeandmertle]’s PVC thumb nuts. They provide a cheap an easy to make way to create thumb-tightenable nuts for your projects.

Starting with a PVC sheet, a series of discs can be cut from it with a hole saw. The hole in the centre of the disc is chosen such that it’s a bit smaller than the required nut, so that it can be pressed into the space with a bolt and a washer. Then a second PVC disc is glued over one side of the first before being sanded to a regular shape, resulting in a captive nut at the centre of a finger-sized and easily turnable handle.

We like this project, and we think that quite a few of you will too. We wonder how much torque it will take, but we’re guessing that a threaded insert could easily be substituted for the nut in more demanding applications. And of course, for more demanding applications you could always try knurling.

There are many ways to build your own Macintosh clone, and while the very latest models remain a little inaccessible, there are plenty of Intel-based so-called “Hackintoshes” which deliver an almost up-to-date experience. But the Mac has been around for a very long time now, and its earliest incarnation only has 128k of RAM and a 68000 processor. What can emulate one of those? Along comes [Matt Evans], with a working Mac 128k emulated on a Raspberry Pi Pico. Such is the power of a modern microcontroller that an RP2040 can now be a Mac!

The granddaddy of all Macs might have been a computer to lust after four decades ago, but the reality was that even at the time the demands of a GUI quickly made it under-powered. The RP2040 has plenty of processing power compared to the 68000 and over twice the Mac’s memory, so it seemed as though emulating the one with the other might be possible. This proved to be the case, using the Musashi 68000 interpreter and a self-built emulator which has been spun into a project of its own called umac. With monochrome VGA and USB for keyboard and mouse, there’s MacPaint on a small LCD screen looking a lot like the real thing.

If you want a 1980s Mac for anything without the joy of reviving original hardware, this represents an extremely cheap way to achieve it. If it can be compiled for microcontrollers with more available memory we could see it would even make for a more useful Mac, though your Mac mileage may vary.

Of course, this isn’t the only take on an early Mac we’ve brought you.

Something that’s a bit of fun at hacker camps such as the recent EMF Camp is to bring along a wired phone and hook it up to the on-camp copper network. It’s a number on the camp network, but pleasingly retro. How about doing the same thing at home? Easy enough if you still have a wired landline, but those are now fast becoming a rarity. Help is at hand though courtesy of [Remy], who’s written about his experiences using a 1960s Dutch phone as a SIP device.

The T65 was the standard Dutch home phone of the 1960s and 1970s, and its curvy grey plastic shape is still not difficult to find in that country.  The guide covers using various different VoIP boxes between such an old machine and the Internet, but there’s more of interest to be found in it. In particular the use of an inline pulse-to-tone converter, either the wonderfully-named DialGizmo, or perhaps closer to our world, a PIC-based kit.

So if you can lay your hands on a VoIP box it’s completely possible to use an aged phone here in 2024. Remember though, a SIP account isn’t the only way to do it.

J. de Kat Angelino, CC BY 3.0.

If you are ever lucky enough to make the trip to Bilund in Denmark, home of LEGO, you can have your portrait taken and rendered in the plastic bricks as pixel art. Having seen that on our travels we were especially interested to watch [Creative Mindstorms]’ video doing something very similar using an entirely LEGO-built machine but taking the images from an AI image generator.

The basic operation of the machine is akin to that of a pick-and-place machine, and despite the relatively large size of a small LEGO square it still has to place at a surprisingly high resolution. This it achieves through the use of a LEGO lead screw for the Y axis and a rack and pinon for the X axis, each driven by a single motor.

The Z axis in this machine simply has to pick up and release a piece, something solved with a little ingenuity, while the magazine of “pixels” was adapted with lower friction from another maker’s design. The software is all written in Python, and takes input from end stop switches to position the machine.

We like this build, and we can appreciate the quantity of work that must have gone into it. If you’re a LEGO fan and can manage the trip to Bilund, there’s plenty of other LEGO goodness to see there.

If you follow the world of microcontrollers, then you’ll probably be familiar with the most recent crop of ten cent parts. They bring power and features previously the preserve of much more expensive chips into the super-budget arena, and they’re appearing in plenty of projects on these pages.

If you’re not familiar with them it can seem daunting to decide which one to use, so to help you [Zach of All Trades] is comparing two of the more common ones. The CH32V003 with a RISC-V core and the PY32F002 with an ARM Cortex M0+ core are both pretty similar on paper, but which should you use?

The video below gives a run-down of each part along with some demonstrations before making its conclusions. The ARM-based part isn’t as quick as the RISC-V one but has a slight edge on peripherals, while the support is where a potential winner emerges in the shape of the CH32. That should be the last word, but for that the PY32 has the distance advantage over its rival of ready availability.

So this look at two families of cheap microcontrollers reveals the pros and cons of each, but in reality it provides an introduction to two sets of powerful chips for pennies.

As we’ve observed before, there are more chips to be found in this market.