2025-11-26 08:00:08
We can’t get enough of [Bettina Neumryn’s] videos. If you haven’t seen her, she takes old electronics magazines, finds interesting projects, and builds them. If you remember these old projects, it is nostalgic, and if you don’t remember them, you can learn a lot about basic electronics and construction techniques. This installment (see below) is an Elektor digital voltmeter and frequency counter from late 1981.
As was common in those days, you could find the PCB layouts in the magazine. In this case, there were two boards. The schematic shows that a counter and display driver chip — a 74C928 — does most of the heavy lifting for the display and the counter.
It is easy to understand how the frequency counter works. You clip the input with a pair of diodes, amplify it a bit, square it with a Schmitt trigger, and then, possibly, prescale it using a divider. The voltmeter is a little trickier: it uses a voltage divider, an op amp, and a 555 to convert the voltage to a frequency.
Of course, finding the parts for an old project can be a challenge. A well-stocked junk drawer doesn’t hurt. A PCB etching setup helps, too.
We’ve looked at her magazine rebuilds before. If you ever get the urge to tackle a project like this, you can find all the grand old magazines online.
2025-11-26 05:00:37
If you work on simple digital projects, just about any bench supply will offer the voltage and current you’re looking for. However, if you’re working with valves, you’ll often find yourself needing much higher voltages that can be tricky to source. [Chappy Happy] has shared a design for a simple HV power supply that should prove useful to vacuum tube enthusiasts.
The build is fairly basic in nature, lacing together some commonly available parts to generate the necessary voltages for working with common vacuum tubes from a 12 volt DC input. Inside the supply is a UC3843A DC boost converter, set up to output high voltage up to around 300 volts DC, with a ripple filter added for good measure. The output can be adjusted with a knob, with a voltmeter on the front panel. There’s also a 12-volt output, and a LM2596 step down converter to produce 6.3 volts for the filament supply. The whole project is built in an old Heathkit project box, and he demonstrates the supply with a simple single-tube amplifier.
If you find yourself regularly whipping up tube circuits, you might like to have something like this on your workbench. Or, you might even consider cooking up your own tubes from scratch if you’re more adventurous like that. Video after the break.
[Thanks to Stephen Walters for the tip!]
2025-11-26 03:30:28
In Dune, the Fremen people of Arrakis practice an odd future hybrid religion called “zensunni.” This adds an extra layer of meaning to the title of [Mark Rehorst]’s Arrakis 3.0 sand table, given that the inspiration for the robotic sand table seems to be Zen gardens from Japan.
The dunes on the tabletop version of Arrakis owe nothing to sand worms, but are instead created a rolling metal ball. With all workings happening below, it looks quite magical to the uninitiated, but of course it’s not magic: it’s magnets. Just beneath the tabletop and its sands, the steel ball is being dragged along by the magnetic field of a powerful neodynium magnet.
That magnet is mounted in a CoreXY motion system that owes more than a little bit to modern 3D printers. Aside from the geometry, it’s using the standard G6 belt we see so often, along with a Duet3D mainboard, NEMA 17 steppers, and many 3D printed parts to hold its aluminum extrusions together. Thanks to that printer-inspired motion system, the ball can whirl around at 2000 mm/s, though [Mark] prefers to run slower: the demo video below shows operation at 1000 mm/s before the sand has been added.
This build was designed for ease of construction and movement: sized at 2’x4′ (about 61 cm x 122 cm), it fits through doors and fits an off-the-shelf slab of coffee table glass, something that [Mark] wishes he’d considered when building version two. That’s the nice thing about jumping in on a project someone’s been iterating for a while: you’ve got the benefit of learning from their mistakes. You can see the roots of this design, and what has changed, from the one he showed us in 2020.
Naturally you’re not limited to CoreXY for a sand table, though it is increasingly popular — we’ve seen examples with polar mechanisms and even a SCARA arm.
2025-11-26 02:00:29
If you are a schoolkid of the right age, you can’t wait to lose a baby tooth. In many cultures, there is a ritual surrounding it, like the tooth fairy, a mouse who trades your tooth for a gift, or burying the tooth somewhere significant. But in 1958, a husband and wife team of physicians wanted children’s teeth for a far different purpose: quantifying the effects of nuclear weapons testing on the human body.
Louise and Eric Reiss, along with some other scientists, worked with Saint Louis University and the Washington School of Dental Medicine to collect and study children’s discarded teeth. They were looking for strontium-90, a nasty byproduct of above-ground nuclear testing. Strontium is similar enough to calcium that consuming it in water and dairy products will leave the material in your bones, including your teeth.
The study took place in the St. Louis area, and the results helped convince John F. Kennedy to sign the Partial Nuclear Test Ban Treaty.
They hoped to gather 50,000 teeth in a year. By 1970, 12 years later, they had picked up over 320,000 donated teeth. While a few kids might have been driven by scientific altruism, it didn’t hurt that the program used colorful posters and promised each child a button to mark their participation.
Children’s teeth were particularly advantageous to use because they are growing and are known to readily absorb radioactive material, which can cause bone tumors.
You might wonder just how much nuclear material is floating around due to bombs. Obviously, there were two bombs set off during the war, as well as the test bombs required to get to that point. Between 1945 and 1980, there were five countries conducting atmospheric tests at thirteen sites. The US, accounting for about 65% of the tests, the USSR, the UK, France, and China detonated 504 nuclear devices equivalent to about 440 megatons of TNT.
Well over 500 bombs with incredible force have put a lot of radioactive material into the atmosphere. That doesn’t count, too, the underground tests that were not always completely contained. For example, there were two detonations in Mississippi where the radiation was contained until they drilled holes for instruments, leaving contaminated soil on the surface. Today, sites like this have “monuments” explaining that you shouldn’t dig in the area.
Of course, above-ground tests are worse, with fallout affecting “downwinders” or people who live downwind of the test site. There have been more than one case of people, unaware of the test, thinking the fallout particles were “hot snow” and playing in it. Test explosions have sent radioactive material into the stratosphere. This isn’t just a problem for people living near the test sites.
By 1961, the team published results showing that strontium-90 levels in the teeth increased depending on when the child was born. Children born in 1963 had levels of strontium-90 fifty times higher than those born in 1950, when there was very little nuclear testing.
The results were part of the reason that President Kennedy agreed to an international partial test ban, as you can see in the Lincoln Presidential Foundation video below. You may find it amazing that people would plan trips to watch tests, and they were even televised.
In 2001, Washington University found 85,000 of the teeth stored away. This allowed the Radiation and Public Health Project to track 3,000 children who were, by now, adults, of course.
Sadly, 12 children who had died from cancer before age 50 had baby teeth with twice the levels of the teeth of people who were still alive at age 50. To be fair, the Nuclear Regulatory Commission has questioned these findings, saying the study is flawed and fails to account for other risk factors.
And teeth don’t just store strontium. In the 1970s, other researchers used baby teeth to track lead ingestion levels. Baby teeth have also played a role in the Flint Water scandal. In South Africa, the Tooth Fairy Project monitored heavy metal pollution in children’s teeth, too.
Teeth aren’t the only indicator of nuclear contamination. Steel is also at risk.
Featured image: “Castle Bravo Blast” by United States Department of Energy.
2025-11-26 00:30:03
[Big Clive] picked up a tiny heater for less than £8 from the usual sources. Would you be shocked to learn that its heating capacity wasn’t as advertised? No, we weren’t either. But [Clive] treats us to his usual fun teardown and analysis in the video below.
A simple test shows that the heater drew about 800 W for a moment and drops as it heats until it stabilizes at about 300 W. Despite that, these units are often touted as 800 W heaters with claims of heating up an entire house in minutes. Inside are a fan, a ceramic heater, and two PCBs.
The ceramic heaters are dwarfed by metal fins used as a heat exchanger. The display uses a clever series of touch sensors to save money on switches. The other board is what actually does the work.
[Clive] was, overall, impressed with the PCB. A triac runs the heaters and the fan. It also includes a thermistor for reading the temperature.
You can learn more about the power supply and how the heater measures up in the video. Suffice it to say, that a cheap heater acts like a cheap heater, although as cheap heaters go, this one is built well enough.
2025-11-25 23:00:31
It’s been twenty-three years since the day Phoenix was released, the web browser that eventually became Firefox. I downloaded it on the first day and installed it on my trusty HP Omnibook 800 laptop, and until this year I’ve used it ever since. Yet after all this time, I’m ready to abandon it for another browser. In the previous article in this series I went into my concerns over the direction being taken by Mozilla with respect to their inclusion of AI features and my worries about privacy in Firefox, and I explained why a plurality of browser engines is important for the Web. Now it’s time to follow me on my search for a replacement, and you may be surprised by one aspect of my eventual choice.
Happily for my own purposes, there are a range of Firefox alternatives which fulfill my browser needs without AI cruft and while allowing me to be a little more at peace with my data security and privacy. There’s Chromium of course even if it’s still way too close to Google for my liking, and there are a host of open-source WebKit and Blink based browsers too numerous to name here.
In the Gecko world that should be an easier jump for a Firefox escapee there are also several choices, for example LibreWolf, and Waterfox. In terms of other browser engines there’s the extremely promising but still early in development Ladybird, and the more mature Servo, which though it is available as a no-frills browser, bills itself as an embedded browser engine. I have not considered some other projects that are either lightweight browser engines, or ones not under significant active development.
Over this summer and autumn then I have tried a huge number of different browsers. Every month or so I build the latest Ladybird and Servo; while I am hugely pleased to see progress they’re both still too buggy for my purposes. Servo is lightning-fast but sometimes likes to get stuck in mobile view, while Ladybird is really showing what it’s going to be but remains for now slow-as-treacle. These are ones to watch, and support.
I gave LibreWolf and Waterfox the most attention over the summer, both of which after the experience I’d describe as like Firefox but with mildly annoying bugs. The inability to video conference reliably is a show-stopper in my line of work, and since my eyesight is no longer what it once was I like my browsers to remember when I have zoomed in on a tab. Meanwhile Waterfox on Android is a great mobile browser, right up until it needs to open a link in another app, and fails. I’m used to the quirks of open-source software after 30+ years experimenting with Linux, but when it comes to productivity I can’t let my software disrupt the flow of Hackaday articles.
It might surprise you after all this open-source enthusiasm then, to see the browser I’ve ended up comfortable with. Vivaldi may be driven by the open-source Blink engine from Chromium and Chrome, but its proprietary front end doesn’t have an open-source licence.
It’s freeware, or free-as-in-beer, and I think the only such software I use. Why, I hear you ask? It’s an effort to produce a browser like Opera used to be in the old days, it’s European which is a significant consideration when it comes to data protection law, and it has (so far) maintained a commitment to privacy while not being evil in the Google motto sense.
It’s quick, I like its interface once the garish coloured default theme has been turned off, and above all, it Just Works. I have my browser back, and I can get on with writing. Should they turn evil I can dump them without a second thought, and hope by then Ladybird has matured enough to suit my needs.
It may not be a trend many of us particularly like, but here in 2025 there’s a sense that the browser has reduced our computers almost to the status of a terminal. It’s thus perhaps the most important piece of software on the device, and in that light I hope you can understand some of the concerns levelled in this series. If you’re reading this from Firefox HQ I’d implore you to follow my advice and go back to what made Firefox so great back in the day, but for the rest of you I’d like to canvass your views on my choice of a worthy replacement. As always, the comments are waiting.
