Misc Hacks

4109 Articles

Molding complex lenses

Molding Complex Optics In A Completely Fluid System

December 9, 2021 by 25 Comments

Traditional lensmaking is a grind — literally. One starts with a piece of glass, rubs it against an abrasive surface to wear away the excess bits, and eventually gets it to just the right shape and size for the job. Whether done by machine or by hand, it’s a time-consuming process, and it sure seems like there’s got to be a better way.

Thanks to [Moran Bercovici] at Technion: Israel Institute of Technology, there is. He leads a team that uses fluids to create complex optics quickly and cheaply, and the process looks remarkably simple. It’s something akin to the injection-molded lenses that are common in mass-produced optical equipment, but with a twist — there’s no mold per se. Instead, a UV-curable resin is injected into a 3D printed constraining ring that’s sitting inside a tank of fluid. The resin takes a shape determined by the geometry of the constraining ring and gravitational forces, hydrostatic forces, and surface tension forces acting on the resin. Once the resin archives the right shape, a blast of UV light cures it. Presto, instant lenses!

The interface between the resin and the restraining fluid makes for incredibly smooth lenses; they quote surface roughness in the range of one nanometer. The use of the fluid bed to constrain the lens also means that this method can be scaled up to lenses 200-mm in diameter or more. The paper is not entirely clear on what fluids are being used, but when we pinged our friend [Zachary Tong] about this, he said he’s heard that the resin is an optical-grade UV adhesive, while the restraining fluid is a mix of glycerol and water.

We’re keen to see [Zach] give this a try — after all, he did something similar lately, albeit on a much smaller scale.

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An Easy Music Visualizer With The Arduino Nano

December 8, 2021 by 3 Comments

Flashing LEDs are all well and good, but they’re even better if they can sync up with ambient sounds or music. [mircemk] has built the LUMAZOID visualizer to do just that, relying on some staple maker components to do so.

The build is open-source, and designed to work with strings of 60, 120, or 180 WS2812B LEDs. An Arduino Nano is charged with running the show, capturing audio via its analog-to-digital converter. A sensitivity pot enables the input level to be set appropriately.

From there, a Fast Fourier Transform is taken, providing data on the intensity of the audio in various frequency bins. The LUMAZOID can be set up to respond to just bass or to all frequencies as a whole. This data is then used to pulse the LEDs in time with the beat.

It’s a fun project that demonstrates the basic techniques required to build an audio-reactive visualizer. We’ve seen some other great builds in this space before, too. Video after the break.

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Complete Hobo Stove Cooking System Could Get You Through The Apocalypse

December 7, 2021 by 70 Comments

Let’s face it, times are hard, and winter is imminent in the northern hemisphere. No matter how much you have to your name, there’s nothing like a cup of hot tea or a warm meal on a cold day. So if you need a snow day activity, consider preparing for whatever may come to pass by building yourself a complete hobo stove system out of empty cans.

[ElectroIntellect]’s stove consists of a 20oz can turned upside down with several holes made in the bottom for heat to rise. The smaller cans are used for cooking pots, and the smallest as a cup. The stove itself is meant to run on flaming twigs stuffed into the base, or a couple of tealight candles if you can only find green wood around.

This comprehensive guide covers everything from building the system to packing it up safely and taking it out to cook in the concrete wilderness. As a special bonus, [ElectroIntellect] brews up some hobo coffee on the stove using an old (clean) sock, and prepares a can of chili in under an hour with candle power.

Too much hardware for you? You can make a disposable rocket stove out of wood.

Twin jet engines mounted on tank treads

Big Wind Is The Meanest Firefighting Tank You Ever Saw

December 6, 2021 by 79 Comments

As the Iraqi army retreated at the end of the first Gulf War, they took the term “scorched Earth policy” quite literally. Kuwaiti oil wells were set alight en masse, creating towering infernos that blackened the sky.

As it turns out, extinguishing a burning oil well is no easy feat. In the face of this environmental disaster, however, a firefighting team from Hungary made a name for themselves out on the desert sands, astride a jet-engined tank named Big Wind.

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Schematic-o-matic

Tricked-Out Breadboard Automatically Draws Schematics Of Whatever You Build

December 6, 2021 by 18 Comments

When it comes to electronic design, breadboarding a circuit is the fun part — the creative juices flow, parts come and go, jumpers build into a tangled mess, but it’s all worth it when the circuit finally comes to life. Then comes the “What have I done?” phase, where you’ve got to backtrack through the circuit to document exactly how you built it. If only there was a better way.

Thanks to [Nick Bild], there is, in the form of the “Schematic-o-matic”, which aims to automate the breadboard documentation process. The trick is using a breadboard where each bus bar is connected to an IO pin on an Arduino Due. A program runs through each point on the breadboard, running a continuity test to see if there’s a jumper connecting them. A Python program then uses the connection list, along with some basic information about where components are plugged into the board, to generate a KiCad schematic.

[Nick] admits the schematics are crude at this point, and that it’s a bit inconvenient to remove some components, like ICs, from the breadboard first to prevent false readings. But this seems like one of those things where getting 80% of the work done automatically and worrying about the rest later is a big win. Plus, we can see a path forward to automatic IC probing, and even measurement of passive components too. But even as it is, it’s a great tool.

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Google Sheet showing wins and losses of sports team. Data automated by IFTTT, Alexa, and Particle

An Overly Complicated Method Of Tracking Your Favorite Sports Team

December 4, 2021 by 3 Comments

Much of the world appears to revolve around sports, and sports tracking is a pretty big business. So how do people keep up with their favorite team? Well, [Jackson] and [Mourad] decided to devise a custom IoT solution.

Their system is a bit convoluted, so bear with us. First, they tell Alexa whether or not the team won or lost that week. Alexa then sends that information to IFTTT where two different Particle Argon boards are constantly polling the results to decide how to respond next. One Particle responds by lighting up an LED, green for a win and red for a loss. Another Particle board displays the results on an LCD screen. But this is where things get tricky. One of the more confusing aspects of their design is one of the Particle boards then signals back to IFTTT, telling it to tally the number of wins and losses. This seems a bit roundabout since the system started with IFTTT in the first place. Regardless, they seemed to be happy with the result and I’m sure they learned something in the process.

This project might not fulfill any functional need given that Alexa knows everything about all our lives already and you could just ask her how your favorite team is doing whenever you want to. But hey, we’re all about learning by doing here at Hackaday and we’re all guilty of building useless projects here and there just because we can. In any case, their project could serve as a good intro to integrating your Particle with IFTTT or Alexa since there appears to be quite a bit of probably unnecessary handshaking going on here.

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Paper Plate Surround Sound System

December 3, 2021 by 14 Comments

With the holiday season, you might turn to paper plates to cut down on dishwashing after having family or friends over. But what do you do with the extras? If you are [TKOR] you make some speakers. The process is fairly simple and if you know how a speaker works, you won’t find any surprises, but there are some neat techniques you might pick up. You can see the video below.

A drill and a steel rod help with the coil winding duty. You can probably adapt the technique to make other kinds of coils and we’d rig up an encoder to count revolutions, too.

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