A conventional tube amplifier has a circuit whose fundamentals were well in place around a hundred years ago, so there are few surprises to be found in building one today. Nevertheless, building one is still a challenge, as [Mike Freda shows us with a stereo amplifier in the video below the break.
The tubes in question are the 12AU7 double triode and 6L6 tetrode, in this case brand new PSVANE parts from China. The design is a very conventional single-ended class A circuit, with both side of the double triode being used for extra gain driving the tetrode. The output uses a tapped transformer with the tap going to the other grid in the tertode, something we dimly remember as being an “ultra-linear” circuit.
There’s an element of workshop entertainment in the video, but aside from that we think it’s the process of characterising the amp and getting its voltages right which is the take-away here. It’s not something many of us do these days, so despite the apparent simplicity of the circuit it’s worth a look.
Over the years we’ve featured many projects which attempt to replicate the feel of physical media when playing music. Usually this involves some kind of token representation of the media, but here’s [Bas] with a different twist (Dutch language, Google Translate link). He’s using the CDs themselves in their cases, identifying them by their barcodes.
At its heart is a Raspberry Pi Pico W and a barcode scanner — after reading the barcode, the Pi calls Discogs to find the tracks, and then uses the Spotify API to find the appropriate links. From there, Home Assistant forwards them along to a smart speaker for playback. As a nice touch, [Bas] designed a 3D printed holder for the electronics which makes the whole thing a bit neater to use.
It’s with sadness that we note the passing of Thomas E. Kurtz, on November 12th. He was co-inventor of the BASIC programming language back in the 1960s, and though his creation may not receive the attention in 2024 that it would have done in 1984, the legacy of his work lives on in the generation of technologists who gained their first taste of computer programming through it.
For the 1980s kids who got beyond this coding masterpiece, BASIC launched many a technology career.
The origins of BASIC lie in the Dartmouth Timesharing System, like similar timesharing operating systems of the day, designed to allow the resources of a single computer to be shared across many terminals. In this case the computer was at Dartmouth College, and BASIC was designed to be a language with which software could be written by average students who perhaps didn’t have a computing background. In the decade that followed it proved ideal for the new microcomputers, and few were the home computers of the era which didn’t boot into some form of BASIC interpreter. Kurtz continued his work as a distinguished academic and educator until his retirement in 1993, but throughout he remained as the guiding hand of the language.
Should you ask a computer scientist their views on BASIC, you’ll undoubtedly hear about its shortcomings, and no doubt mention will be made of the GOTO statement and how it makes larger projects very difficult to write. This is all true, but at the same time it misses the point of it being a readily understandable language for first-time users of machines with very little in the way of resources. It was the perfect programming start for a 1970s or 1980s beginner, and once its limitations had been reached it provided the impetus for a move to higher things. We’ve not written a serious BASIC program in over three decades, but we’re indebted to Thomas Kurtz and his collaborator for what they gave us.
In the iconic 1990s TV series The X Files, David Duchovny’s FBI agent-paranormal investigator Fox Mulder has a poster on his office wall. It shows a flying saucer in flight, with the slogan “I Want To Believe”. It perfectly sums up the dilemma the character faces. And while I’m guessing that only a few Hackaday readers have gone down the full lizard-people rabbit hole, wanting to believe is probably something that a lot of us who love sci-fi understand. It would be a fascinating event for science if a real extraterrestrial craft would show up, so of course we want to believe to some extent, even if we’re not seriously expecting it to appear in a Midwestern cornfield and break out the probes any time soon.
Outside the realm of TV drama and science fiction it’s a sentiment that also applies in more credible situations. Back at the end of the 1980s for example when so-called cold fusion became a global story it seemed as though we might be on the verge of the Holy Grail of clean energy breakthroughs. Sadly we never got our Mr. Fusion to power our DeLorean, and the scientific proof was revealed to be on very weak foundations. The careers of the two researchers involved were irreparably damaged, and the entire field became a byword for junk science. A more recently story in a similar vein is the EM drive, a theoretical reactionless force generator that was promising enough at one point that even NASA performed some research on it. Sadly there were no magic engines forthcoming, so while it was worth reporting on the initial excitement, we’re guessing the story won’t come back.
When evaluating a scientific or technical breakthrough that seems as miraculous as it is unexpected then, of course we all want to believe. We evaluate based on the information we have in front of us though, and we all have a credibility pyramid. There’s nothing wrong with having an interest in fields that are more hope than delivery, indeed almost every technology that powers our world will at some time have to overcome skepticism in its gestation period. Perhaps it’s best to say that it’s okay to have hope, but hope shouldn’t override our scrutiny of the proof. Of course I want a perpetual motion machine, who wouldn’t, but as a fictional engineer once allegedly said, “Ye cannae change the laws of physics”.
An Example Here In 2024
The hydrogen future is very seductive. But does it work? Jóhann Heiðar Árnason, CC BY-SA 3.0.
All this introspection has been brought to the fore for me by something very much in the present, the so-called hydrogen economy. It’s difficult to ignore our climate emergency, and among the energy solutions aimed at doing something about it, hydrogen seems very promising.
It’s really easy to make from water by electrolysis, there are several ways to turn it into useful energy, and the idea is that if you can store it for later use you’re on to a winner. We’ve seen hydrogen cars, trucks, aircraft, heavy machinery, trains, and even the gas supplanting methane in the domestic grid, so surely the hydrogen future is well under way, right?
Sadly not, because as many a pilot project has shown, it’s difficult to store or transport, it makes many existing metal fittings brittle, and the environmental benefit is often negated by the hydrogen being generated from higher carbon electrical supplies. We still want to believe, but we can’t claim it’s delivering yet.
Whenever we feature a hydrogen-based story, as for example with this experimental storage tech from Swiss researchers, there is no shortage of comments about all of hydrogen’s shortcomings, and some even accuse us of somehow being the snake-oil salesmen shilling the questionable product. I feel this misses the point, that even though in almost all cases the battery is for now the better option, we cover interesting technology stories regardless of judgements over their eventual success. Hydrogen has enough real science and engineering behind it that its problems might one day be overcome, thus we’d be doing our readers a disservice if we didn’t cover it. There are sometimes newsworthy stories upon which we very much take a credible stand based on opinion, but when it comes to pure tech stories such as a hydrogen vehicle we’re simply reporting on the story because we find it interesting and we think you will too. We don’t know that the breakthrough engineering work won’t occur, but we do know that it hasn’t yet.
So when looking at a piece of technology that’s not delivered on its promise, ask for a moment whether there’s a likely “yet” on the end of the sentence without too much of a suspension of credibility. You might find yourself pleasantly surprised.
To a casual observer of public discourse here in 2024 it seem extremely odd that the issue of replacing coal fired power stations with wind turbines is a matter of controversy, whether in America or Europe it’s an issue which causes some sparks to fly. The Atlantic has a recent article with a set of pictures from a gentler time in which the industrious nature of Nebraskan farmers in the 1890s receives praise as they create a wide variety of home-made wind turbines.
Farmers have always been the best hardware hackers, using what they have at hand to solve their problems and create the things they need. Perhaps out image of agricultural wind power is one of commercially produced wind pumps, but these are the generation of home-made devices which preceded that. Some of them look conventional to modern eyes, but others such as the horizontal “Jumbo” turbines have little equivalent today.
It’s easy to forget with so many energy sources at our disposal, that in the past the locality affected the choice of motive power. The Netherlands doesn’t have windmills because they are pretty, but because hundreds of years ago they lacked handy coal mines or convenient heads of water. Similarly out in the Nebraskan prairies they had plenty of wind, and never the folk to pass up on an opportunity, they made the best of it. And we’re very glad over a century later, that someone took the time to record their work.
We’ll go out on a limb here and say that a large portion of Hackaday readers are also boat-builders. That’s a bold statement, but as the term applies to anyone who has built a boat, we’d argue that it encompasses anyone who’s run off a Benchy, the popular 3D printer test model. Among all you newfound mariners, certainly a significant number must have looked at their Benchy and wondered what a full-sized one would be like. Those daydreams of being captain of your ship may not have been realized, but [Dr. D-Flo] has made them a reality for himself with what he claims is the world’s largest Benchy. It floats, and carries him down the waterways of Tennessee in style!
The video below is long but has all the details. The three sections of the boat were printed in PETG on a printer with a one cubic meter build volume, and a few liberties had to be taken with the design to ensure it can be used as a real boat. The infill gaps are filled with expanding foam to provide extra buoyancy, and an aluminium plate is attached to the bottom for strength. The keel meanwhile is a 3D printed sectional mold filled with concrete. The cabin is printed in PETG again, and with the addition of controls and a solar powered trolling motor, the vessel is ready to go. Let’s face it, we all want a try!
On the bench where this is being written, there’s a Mitutoyo vernier caliper. It’s the base model with a proper vernier scale, but it’s beautifully made, and it’s enjoyable to see younger hardware hackers puzzle over how to use it. It cost about thirty British pounds a few years ago, but when it comes to quality metrology instruments that’s really cheap. The sky really is the limit for those in search of ultimate accuracy and precision. We can see then why this Redditor was upset when the $400 Mitutoyo they ordered from Amazon turned out to be nothing of the sort. We can’t even call it a fake, it’s just a very cheap instrument stuffed oddly, into a genuine Mitutoyo box.
Naturally we hope they received a refund, but it does raise the question when buying from large online retailers; how much are we prepared to risk? We buy plenty of stuff from AliExpress in out community, but in that case the slight element of chance which comes with random Chinese manufacture is offset by the low prices. Meanwhile the likes of Amazon have worked hard to establish themselves as trusted brands, but is that misplaced? They are after all simply clearing houses for third party products, and evidently have little care for what’s in the box. The £30 base model caliper mentioned above is an acceptable punt, but at what point should we go to a specialist and pay more for some confidence in the product?
It’s a question worth pondering as we hit the “Buy now” button without thinking. What’s your view? Let us know in the comments. Meanwhile, we can all be caught with our online purchases.
It was Supercon this weekend, and Hackaday staffers made their way to Pasadena for what was by all accounts an excellent event. Now they’re all on their way home on red-eye flights and far from their benches, so spare a thought for the lonely editor holding the fort while they’ve been having fun. The supply of cool hacks for your entertainment must continue, so what’s to be done? Fortunately Hackaday writer [Anne Ogborn] has the answer, in the form of an automated Hackaday article generator.
We once had a commenter make a withering insult that one of our contributors’ writing styles looked like the work of an AI driven bot, a sentence that the writer in question treasures enough to have incorporated in their Hackaday email signature. [Anne] is a data scientist and Prolog programmer by trade so knows a bit about AI, and she has no need for such frippery. Instead she’s made a deck of cards each marked with a common theme among the work featured here, and generating new article titles is a simple case of drawing cards from the pack and assembling the resulting sentence.
The result is both amusing and we think, uncannily on the mark. Who wouldn’t want an ESP8266 powered cardboard drone? We think it will make a valuable addition to the Hackaday armoury, to be brought out on days such as the first of April, when there’s always an unexpected shortage of hacks. Video below the break.
When the project description starts with the sentence “I use an RC remote and receiver, an esp32, high-current motor drivers, servos, an FPV camera, and a little propane”, you know that this is one which deserves a second look. And so [gearscodeandfire]’s Halloween project caught our eye. It’s a pink Power Wheels jeep driven by a skeletal rider, and the best part is that the whole thing is remote controlled down to a pan-and-tilt skull, a first-person video feed, and even real flames.
At its heart is an ESP32 with a set of motor controllers and relays to do the heavy lifting. The controller is a standard radio remote controller, and the first-person view is an analogue feed as you’d find on a drone. The skeleton is given a child-like appearance by discarding the original adult-proportioned plastic skull and replacing it with a much larger item. The thought that plastic Halloween skulls are available in a range of standard sizes and can be considered as a part in their own right is something we find amusing. The propane burner is supplied from a small cylinder via a solenoid valve, and ignited with the spark from a high-voltage transformer.
The result, we think, wins Halloween hands down. Twelve-foot skeletons are SO 2023!
The regenerative radio is long-ago superseded in commercial receivers, but it remains a common project for electronics or radio enthusiasts seeking to make a simple receiver. It’s most often seen for AM band receivers or perhaps shortwave ham band ones, but it’s a circuit which also works at much higher frequencies. [Perian Marcel] has done just this, with a regenerative receiver for the FM broadcast band.
The principle of a regenerative receiver is that it takes a tuned radio frequency receiver with a wide bandwidth and poor performance, and applies feedback to the point at which the circuit is almost but not quite oscillating. This has the effect of hugely increasing the “Q”, or quality factor of the receiver, giving it much more sensitivity and a narrow bandwidth. They’re tricky to tune but they can give reasonable performance, and they will happily slope-demodulate an FM transmission.
This one uses two tubes from consumer grade TV receivers, the “P” at the start of the part number being the giveaway for a 300mA series heater chain. The RF triode-pentode isn’t a radio part at all, instead it’s a mundane TV field oscillator part pushed into service at higher frequencies, while the other triode-pentode serves as an audio amplifier. The original circuit from which this one is adapted is available online, All in all it’s a neat project, and a reminder that exotic parts aren’t always necessary at higher frequencies. The video is below the break.
When we think of an m.2 slot in our laptop or similar, it’s usually in the context of its PCI connectivity for high-speed applications such as solid state disks. It’s a connector that offers much more than that interface though, making it suitable for some unexpected add-ons. As an example [MagicWolfi] has produced an m.2 card which contains the equivalent of a Raspberry Pi Pico.
The board itself has the familiar m.2 edge connector at the bottom, and the RP2040 GPIO lines as postage-stamp indentations round the edges. On the m.2 front is uses the USB interface as well as a UART and the I2C lines, as well as some of the interfaces we’re less familiar with such as ALERT, WAKE, DISABLE1/2, LED 1/2, and VENDOR_DEFINED.
On one level this provides a handy internal microcontroller card with which you can do all the things you’d expect from a Pi Pico, but on another it provides the fascinating possibility of the Pico performing a watchdog or other function for the host device. We would be genuinely interested to hear more about the use of the m.2 slot in this way.
Face it, we’ve all at some time or other looked at our hot glue guns, and thought “I wonder if I could use that for 3D printing!”. [Proper Printing] didn’t just think it, he’s made a working hot glue 3D printer. As you’d expect, it’s the extruder which forms the hack here.
A Dremel hot glue gun supplies the hot end, whose mains heater cartridge is replaced with a low voltage one with he help of a piece of brass tube. He already has his own design for an extruder for larger diameters, so he mates this with the hot end. Finally the nozzle is tapped with a thread to fit an airbrush nozzle for printing, and he’s ready tp print. With a much lower temperature and an unheated bed it extrudes, but it takes multiple attempts and several redesigns of the mechanical parts of the extruder before he finally ended up with the plastic shell of the glue gun as part of the assembly.
The last touch is a glue stick magazine that drops new sticks into a funnel on top of the extruder, and it’s printing a Benchy. At this point you might be asking why go to all this effort, but when you consider that there are other interesting materials which are only available in stick form it’s clear that this goes beyond the glue. If you’re up for more hot glue gun oddities meanwhile, in the past we’ve shown you the opposite process to this one.
For a first try at an electric vehicle conversion we’re guessing that most would pick a small city car as a base vehicle, or perhaps a Kei van. Not [LiamTronix], who instead chose to do it with an old Ferguson tractor. It might not be the most promising of EV platforms, but as you can see in the video below, it results in a surprisingly practical agricultural vehicle.
A 1950s or 1960s tractor like the Ferguson usually has its engine as a structural member with the bellhousing taking the full strength of the machine and the front axle attached to the front of the block. Thus after he’s extracted the machine from its barn we see him parting engine and gearbox with plenty of support, as it’s a surprisingly hazardous process. These conversions rely upon making a precise plate to mount the motor perfectly in line with the input shaft. We see this process, plus that of making the splined coupler using the center of the old clutch plate. It’s been a while since we last did a clutch alignment, and seeing him using a 3D printed alignment tool we wish we’d had our printer back then.
The motor is surprisingly a DC unit, which he first tests with a 12 V car battery. We see the building of a hefty steel frame to take the place of the engine block in the structure, and then a battery pack that’s beautifully built. The final tractor at the end of the video still has a few additions before it’s finished, but it’s a usable machine we wouldn’t be ashamed to have for small round-the-farm tasks.
Surprisingly there haven’t been as many electric tractors on these pages as you’d expect, though we’ve seen some commercial ones.
If you’re looking for a hackerspace while on your travels, there is more than one website which shows them on a map, and even tells you whether or not they are open. This last feature is powered by SpaceAPI, a standard way for hackerspaces to publish information about themselves, including whether or not they are closed.
The lights are a set of addressable LEDs and the brain is an ESP32, making this an accessible project for most hackers with the time to assemble it. Unsurprisingly then it’s not the first such map we’ve seen, though it’s considerably more ambitious than the last one. Meanwhile if your hackerspace doesn’t have SpaceAPI yet or you’re simply curious about the whole thing, we took a look at it back in 2021.
A British journalistic trope involves the phrase “The pound in your pocket”, a derisory reference to the 1960s Prime Minister Harold Wilson’s use of it to try to persuade the public that a proposed currency devaluation wouldn’t affect them. Nearly six decades later not so many Brits carry physical pounds in their pockets as electronic transfers have become more prevalent, but the currency remains. So much so that the governor of the Bank of England has had to reassure the world that the pound won’t be replaced by a proposed “Britcoin” cryptocurrency should that be introduced.
Normally matters of monetary policy aren’t within Hackaday’s remit, but since the UK is not the only country to mull over the idea of a tightly regulated cryptocurrency tied to their existing one, there’s a privacy angle to be considered while still steering clear of the fog of cryptocurrency enthusiasts. The problem is that reading the justification for the new digital pound from the Bank of England, it’s very difficult to see much it offers which isn’t already offered by existing cashless payment systems. Meanwhile it offers to them a blank regulatory sheet upon which they can write any new rules they want, and since that inevitably means some of those rules will affect digital privacy in a negative manner, it should be a worry to anyone whose government has considered the idea. Being at pains to tell us that we’ll still be able to see a picture of the King (or a dead President, or a set of bridges) on a bit of paper thus feels like an irrelevance as increasingly few of us handle banknotes much anyway these days. Perhaps that act in itself will now become more of an act of protest. And just when we’d persuaded our hackerspaces to go cashless, too.
Back in the summer our eye was caught by [Jazzy Jane]’s new signal generator, or perhaps we should say her new-to-her signal generator. It’s an Advance E1 from around 1950, and it was particularly interesting from here because it matches the model on the shelf above this bench. She’s back with a new video on the E1, allowing us a further look inside it as she replaces a dead capacitor, gets its audio oscillator working, and upgrades its sockets.
Treating us to a further peek inside the unit, first up is a leaky capacitor. Then a knotty question for old tech enthusiasts, to upgrade or not? The ancient co-ax connectors are out of place on a modern bench, so does originality matter enough to give it a set of BNC sockets? We’d tend to agree; just because we have some adapters for the unit here doesn’t mean it’s convenient. Following on from that is a period variable frequency audio mod which has failed, so out that comes and a little fault-finding is required to get the wiring of the audio transformer.
These instruments are not by any means compact, but they do have the advantage of being exceptionally well-built and above all cheap. We hope readers appreciate videos like the one below the break, and that you’re encouraged not to be scared of diving in to older items like this one to fix them. Meanwhile the first installment is here.
An unlikely theatre for an act in the right-to-repair saga came last year in the form of McDonalds restaurants, whose McFlurry ice cream machines are prone to breakdown. The manufacturer had locked them down, and a franchisee with a broken machine had no option but to call them for an expensive repair job. iFixit and Public Knowledge challenged this with a request for a DMCA exemption from the Copyright Office, and now news emerges that this has been granted.
The exemption in question isn’t specific to McDonalds, instead it applies to retail food preparation equipment in general, which includes ice-cream machines. We’re guessing that franchisees won’t be breaking out the screwdrivers either, instead it’s likely to lower significantly the cost of a service contract for them and any other food industry operators hit with the same problem. Meanwhile any hackers who’ve picked up an old machine can now fix it themselves without breaking the law, and maybe the chances of your local Mickey D’s having no McFlurries have gone down.
This story has featured more than once on these pages, so catch up here, and here.
It’s a staple of spy thriller movies, that the protagonist has some kind of electronic scanner with which he theatrically searches his hotel room to reveal the bad guys’ attempt to bug him. The bug of course always had a flashing LED to make it really obvious to viewers, and the scanner was made by the props department to look all cool and futuristic.
It’s not so far-fetched though, while bugs and hidden cameras in for example an Airbnb may not have flashing LEDs, they still emit RF and can be detected with a signal strength meter. That’s the premise behind [RamboRogers]’ RF hunter, the spy movie electronic scanner made real.
At the rear of the device is an ESP32, but the front end is an AD8317 RF detector chip. This is an interesting and useful component, in that it contains a logarithmic amplifier such that it produces a voltage proportional to the RF input in decibels. You’ll find it at the heart of an RF power meter, but it’s also perfect for a precision field strength meter like this one. That movie spy would have a much higher chance of finding the bug with one of these.
When making a birthday cake a bit more personal, one can create a novelty themed confection appropriate for the lucky recipient. In the case of [Spencer Owen], who you may know as the creator of the RC2014 retrocomputing ecosystem, it was appropriate to have one of the little machines at work somewhere, so [peahen] did just that. The result is a cake in the shape of an IMSAI 8080 microcomputer, but it does more than just look the part. This is a working replica of the classic machine, powered as you might expect by an RC2014 sitting next to it.
The lights are a set of addressable LEDs, and the switches are made from appropriately colored sweets. Sadly the plan to make these capacitive touch switched failed as the wiring became buried in the icing, but the LEDs deserve a second look. They’re encased in translucent heatshrink sleeving which is embedded under a layer of white icing, which is translucent enough, but on top for the classic panel light look are a set of edible cake-maker’s jewels. Best of all while all except the electronics is edible, the front panel is robust enough to have been removed from the cake in one and thus will live on.
We rather like the idea of electronics meeting sugarcraft, because fondant is a surprisingly versatile medium that deserves attention much further than just confectionery. We remember it being a popular cheap way to experiment with 3D printing back at the dawn of open source printers, and it still has some potential. Meanwhile if you’ve not seen the RC2014 we reviewed its original version back in 2016, and since then it’s evolved to become an ecosystem in its own right.
Conectar
