What’s In A Washer?

May 12, 2025 by Al Williams 15 Comments

Some things are so common you forget about them. How often do you think about an ordinary resistor, for example? Yet if you have a bad resistor, you’ll find it can be a big problem. Plus, how can you really understand electronics if you don’t know all the subtle details of a resistor? In the mechanical world, you could make the same arguments about the washer, and [New Mind] is ready to explain the history and the gory details of using washers in a recent video that you can see below.

The simple answer is that washers allow a bolt to fit in a hole otherwise too large, but that’s only a small part of the story. Technically, what you are really doing is distributing the load of a threaded fastener. However, washers can also act as spacers or springs. Some washers can lock, and some indicate various things like wear or preloading conditions.

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What Happened To WWW.?

May 5, 2025 by Lewin Day 59 Comments

Once upon a time, typing “www” at the start of a URL was as automatic as breathing. And yet, these days, most of us go straight to “hackaday.com” without bothering with those three letters that once defined the internet.

Have you ever wondered why those letters were there in the first place, and when exactly they became optional? Let’s dig into the archaeology of the early web and trace how this ubiquitous prefix went from essential to obsolete.

Where Did You Go?

*The first website didn’t bother with any of that www. nonsense! Credit: author screenshot*

It may shock you to find out that the “www.” prefix was actually never really a key feature or necessity at all. To understand why, we need only contemplate the very first website, created by Tim Berners-Lee at CERN in 1990. Running on a NeXT workstation employed as a server, the site could be accessed at a simple URL: “http//info.cern.ch/”—no WWW needed. Berners-Lee had invented the World Wide Web, and called it as such, but he hadn’t included the prefix in his URL at all. So where did it come from? Continue reading “What Happened To WWW.?” →

Vintage Stereo Stack Becomes Neat PC Case

April 30, 2025 by Lewin Day 8 Comments

Vintage hi-fi gear has a look and feel all its own. [ThunderOwl] happened to be playing in this space, turning a heavily-modified Technics stereo stack into an awesome neo-retro PC case. Meet the “TechnicsPC!”

You have to hunt across BlueSky for the goodies, but it’s well worth it. The main build concerned throwing a PC into an old Technics receiver, along with a pair of LCD displays and a bunch of buttons for control. If the big screens weren’t enough of a tell that you’re looking at an anachronism, the USB ports just below the power switch will tip you off. A later addition saw a former Technics tuner module stripped out and refitted with card readers and a DVD/CD drive. Perhaps the most era-appropriate addition, though, is the scrolling LED display on top. Stuffed inside another tuner module, it’s a super 90s touch that somehow just works.

These days, off-the-shelf computers are so fancy and glowy that DIY casemodding has fallen away from the public consciousness. And yet, every so often, we see a magnificent build like this one that reminds us just how creative modders can really be. Video after the break.

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Deriving The Reactance Formulas

April 28, 2025 by Al Williams 9 Comments

If you’ve dealt with reactance, you surely know the two equations for computing inductive and capacitive reactance. But unless you’ve really dug into it, you may only know the formula the way a school kid knows how to find the area of a circle. You have to have a bit of higher math to figure out why the equation is what it is. [Old Hack EE] wanted to figure out why the formulas are what they are, so he dug in and shared what he learned in a video you can see below.

The key to understanding this is simple. The reactance describes the voltage over the current through the element, just like resistance. The difference is that a resistance is just a single number. A reactance is a curve that gives you a different value at different frequencies. That’s because current and voltage are out of phase through a reactance, so it isn’t as easy as just dividing.

If you know calculus, the video will make a lot of sense. If you don’t know calculus, you might have a few moments of panic, but you can make it. If you think of frequency in Hertz as cycles per second, all the 2π you find in these equations convert Hz to “radian frequency” since one cycle per second is really 360 degrees of the sine wave in one second. There are 2π radians in a circle, so it makes sense.

We love developing intuition about things that seem fundamental but have a lot of depth to them that we usually ignore. If you need a refresher or a jump start on calculus, it isn’t as hard as you probably think. Engineers usually use vectors or imaginary numbers to deal with reactance, and we’ve talked about that too, if you want to learn more.

X-Rays From An Overdriven Magnetron

April 28, 2025 by Dan Maloney 34 Comments

If you say that you’re “nuking” something, pretty much everyone will know that you mean you’re heating something in the microwave. It’s technically incorrect, of course, as the magnetron inside the oven emits only non-ionizing radiation, and is completely incapable of generating ionizing radiation such as X-rays. Right?

Perhaps not, as these experiments with an overdriven magnetron suggest. First off, this is really something you shouldn’t try; aside from the obvious hazards that attend any attempt to generate ionizing radiation, there are risks aplenty here. First of all, modifying magnetrons as [SciTubeHD] did here is risky thanks to the toxic beryllium they contain, and the power supply he used, which features a DIY flyback transformer we recently featured, generates potentially dangerous voltages. You’ve been warned.

For the experiment, [SciTubeHD] stripped the magnets off a magnetron and connected his 40-kV AC power supply between the filament and the metal case of the tube. We’re not completely clear to us how this creates X-rays, but it appears to do so given the distinctive glow given off by an intensifying screen harvested from an old medical X-ray film cassette. The light is faint, but there’s enough to see the shadows of metallic objects like keys and PCBs positioned between the tube and the intensifying screen.

Are there any practical applications for this? Probably not, especially considering the potential risks. But it’s still pretty cool, and we’re suitably impressed that magnetrons can be repurposed like this.

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Another Coil Winder Project

April 26, 2025 by Al Williams 4 Comments

If you build electronics, you will eventually need a coil. If you spend any time winding one, you are almost guaranteed to think about building a coil winder. Maybe that’s why so many people do. [Jtacha] did a take on the project, and we were impressed — it looks great.

The device has a keypad and an LCD. You can enter a number of turns or the desired inductance. It also lets you wind at an angle. So it is suitable for RF coils, Tesla coils, or any other reason you need a coil.

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Remembering Heathkit

April 26, 2025 by Al Williams 22 Comments

While most hams and hackers have at least heard of Heathkit, most people don’t know the strange origin story of the legendary company. [Ham Radio Gizmos] takes us all through the story.

In case you don’t remember, Heathkit produced everything from shortwave radios to color TVs to test equipment and even computers. But, for the most part, when you bought something from them, you didn’t get a finished product. You got a bag full of parts and truly amazing instructions about how to put them together. Why? Well, if you are reading Hackaday, you probably know why. But some people did it to learn more about electronics. Others were attracted by the lower prices you paid for some things if you built them yourself. Others just liked the challenge.

But Heathkit’s original kit wasn’t electronic at all. It was an airplane kit. Not a model airplane, it was an actual airplane. Edward Heath sold airplane kits at the affordable price around $1,000. In 1926, that was quite a bit of money, but apparently still less than a commercial airplane.

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