DIY Metal Detector Gives You The Mettle To Find Some Medals

Hurricane season is rapidly approaching those of us who live in the northern hemisphere. While that does come with a good deal of stress for any homeowners who live in the potential paths of storms it also comes with some opportunities for treasure hunting. Storms tend to wash up all kinds of things from the sea, and if you are equipped with this DIY metal detector you could be unearthing all kinds of interesting tchotchkes from the depths this year.

The metal detector comes to us from [mircemk] who is known for building simple yet effective metal detectors. Unlike his previous builds, this one uses only a single integrated circuit, the TL804 operational amplifier. It also works on the principle of beat-balance which is an amalgamation of two unique methods of detecting metal.  When the wire coils detect a piece of metal in the ground, the information is fed to an earpiece through an audio jack which rounds out this straightforward build.

[mircemk] reports that this metal detector can detect small objects like coins up to 15 cm deep, and larger metal objects up to 50 cm. Of course, to build this you will also need the support components, wire, and time to tune the circuit. All things considered, though it’s a great entryway into the hobby.

Want to learn more about metal detecting? Check out this similar-looking build which works on the induction balance principle.

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Rural Hacker De-Crufts And Rebuilds Hydroelectric Generator

YouTuber [Linguoer] has a knack, and it’s one that we don’t often see on the pages of Hackaday: rewinding and rebuilding dilapidated motors and generators. In the video below, you’ll see [Lin] take a hydroelectric turbine and generator that looks like it’s been sitting at the bottom of a lake, and turn it into a working unit, all while wearing her trademark blue and yellow denim jumpsuit.

Where as most makers would have used a MIG or TIG welder, [Linguoer] uses a simple (probably A/C) stick welder. Generator windings are calculated and wound by hand, and the carcass of what used to be the generator is sandblasted out in the open. Missing parts are fabricated from scratch using nothing more than an angle grinder. “Simple” is the order of the day.

[Linguoer] often refers to herself as “Village Girl”. Whatever specialty tools she uses, they are elementary. And whatever methods she uses, they are manual. You will get the idea very quickly that [Linguoer] isn’t just a person with a skill, but a person with a passion for getting things done no matter the circumstances. [Linguoer] is a hacker if there ever was one!

If hydroelectric hacks spin your pelton wheel, give this Impressive Off-Grid Hydroelectric Plant a whirl.

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Charger Caddy Shows What 3D Printers Were Meant For

As computers became more popular in the late 80s and into the 90s, they vastly changed their environments. Of course the technological changes were obvious, but plenty of other things changed to accommodate this new technology as well. For example, furniture started to include design elements to accommodate the desktop computer, with pass-through ports in the back of the desks to facilitate cable management. While these are less common features now there are plenty of desks still have them, this 3D printed design modernizes them in a simple yet revolutionary way.

While these ports may have originally hosted thick VGA cables, parallel printer cables (if they would fit), and other now-obsolete wiring, modern technology uses simpler, smaller solutions. This doesn’t mean that they aren’t any less in need of management, though. This print was designed to hold these smaller wires such as laptop chargers, phone chargers, and other USB cables inside the port. A cap on the top of the print keeps everything hidden until it is lifted by hand, where a cable can be selected and pulled up to the top of the desk.

While it might seem like a simple project at first, the elegance of this solution demonstrates excellent use of design principles and a knack for integrating slightly older design decisions with modern technology. If you have a 3D printer and a cable management port on your desk, the print is available on Thingiverse. Not every project needs a complicated solution to solve a problem, like this automatic solar tracker we recently saw which uses no complicated electronics or algorithms to reliably point itself at the sun.

Little Flash Charges In 40 Seconds Thanks To Super Capacitors

We’ve all committed the sin of making a little arduino robot and running it off AA batteries. Little Flash is better than that and runs off three 350 F capacitors.

In fact, that’s the entire mission of the robot. [Mike Rigsby] wants people to know there’s a better way. What’s really cool is that 10 A for 40 seconds lets the robot run for over 25 minutes!

The robot itself is really simple. The case is 3D printed with an eye towards simplicity. The brains are an Arduino nano and the primary input is a bump sensor. The robot runs around randomly, but avoids getting stuck with the classic reverse-and-turn on collision.

It’s cool to see how far these capacitors have come. We remember people wondering about these high priced specialty parts when they first dropped on the hobby scene, but they’re becoming more and more prevalent compared to other solutions such as coin-cells and solder tab lithium batteries for PCB power solutions.

You Didn’t See Graphite Around This Geiger Counter

Even if you don’t work in a nuclear power plant, you might still want to use a Geiger counter simply out of curiosity. It turns out that there are a lot of things around which emit ionizing radiation naturally, for example granite, the sun, or bananas. If you’ve ever wondered about any of these objects, or just the space you live in, it turns out that putting together a simple Geiger counter is pretty straightforward as [Alex] shows us.

The core of the Geiger counter is the tube that detects the radiation. That’s not something you’ll be able to make on your own (probably) but once you have it the rest of the build comes together quickly. A few circuit boards to provide the tube with the high voltage it needs, a power source, and a 3D printed case make this Geiger counter look like it was ordered from a Fluke catalog.

The project isn’t quite finished ([Alex] is still waiting on a BNC connector to arrive) but seems to work great and isn’t too complicated to put together, as far as Geiger counters go. He did use a lathe for some parts which not everyone will have on hand, but a quick trip to a makerspace or machinist will get you that part too. We’ve seen some other parts bin Geiger counters too, so there’s always a way around things like this.

Robot’s Actions And Our Reactions

If you walk into a dog owner’s home that dog is probably going to make a beeline to see if you are a threat. If you walk into a cat owner’s home, you may see the cat wandering around, if it even chooses to grace you with its presence. For some people, a dog’s direct approach can be nerve-wracking, or even scary depending on their history and relative size of the dog. Still, these domestic animals are easy to empathize with especially if you or your family have a pet. They have faces which can convey curiosity or smug indifference but what if you were asked to judge the intent of something with no analogs to our own physical features like a face or limbs? That is what researchers at the IDC Herzliya in Israel and Cornell University in the US asked when they made the Greeting Machine to move a moon-like sphere around a planet-like sphere.

Participants were asked to gauge their feelings about the robot after watching the robot move in different patterns. It turns out that something as simple as a sphere tracing across the surface of another sphere can stir consistent and predictable emotions in people even though the shapes do not resemble a human, domestic pet, or anything but a snowman’s abdomen. This makes us think about how our own robots must be perceived by people who are not mired in circuits all day. Certainly, a robot jellyfish lazing about in the Atlantic must feel less threatening than a laser pointer with a taste for human eyeballs.


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Morse Code Keyboard 1939 Style!

If you want to learn Morse code and you don’t have a teacher, you’d probably just head over to a website or download a phone app. Before that, you probably bought a cassette tape or a phonograph record. But how did you learn Morse if you didn’t have any of that and didn’t know anyone who could send you practice? Sure, you could listen to the radio, but in 1939 that might be difficult, especially to find people sending slow enough for you to copy.

Wireless World for August 3rd, 1939, has the answer in an article by [A. R. Knipe] on page 109. While you probably wouldn’t use it today, it is a great example of how ingenious you can be when you don’t have an Arduino and all the other accoutrements we take for granted today.

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