Magnesium And Copper Makes An Emergency Flashlight

August 8, 2024 by 17 Comments

Many of us store a flashlight around the house for use in emergency situations. Usually, regular alkaline batteries are fine for this task, as they’ll last a good few years, and you remember to swap them out from time to time. Alternatively, you can make one that lasts virtually indefinitely in storage, and uses some simple chemistry, as [JGJMatt] demonstrates.

The flashlight uses 3D printing to create a custom battery using magnesium and copper as the anode and cathode respectively. Copper tape is wound around a rectangular part to create several cathode plates, while magnesium ribbon is affixed to create the anodes. Cotton wool is then stuffed into the 3D-printed battery housing to serve as a storage medium for the electrolyte—in this case, plain tap water.

The custom battery is paired with a simple LED flashlight circuit in its own 3D-printed housing. The idea is that when a blackout strikes, you can assemble the LED flashlight with your custom battery, and then soak it in water. This will activate the battery, producing around 4.5 V and 20 mA to light the LED.

It’s by no means going to be a bright flashlight, and realistically, it’s probably less reliable than just keeping a a regular battery-powered example around. Particularly given the possibility of your homebrew battery corroding over the years unless it’s kept meticulously dry. But that’s not to say that water-activated batteries don’t have their applications, and anyway it’s a fun project that shows how simple batteries really are at their basic level. Consider it as a useful teaching project if you have children interested in science and electricity!

Tulip Is A Micropython Synth Workstation, In An ESP32

August 8, 2024 by 6 Comments

We’re not sure exactly what Tulip is, because it’s so many things all at once. It’s a music-making environment that’s programmable in Python, runs on your big computer or on an ESP32-S3, and comes complete with some nice sounding synth engines, a sequencer, and a drum machine all built in. It’s like your dream late-1980s synthesizer workstation, but running on a dev board that you can get for a song.

And because Tulip is made of open-source software and hardware, you can extend the heck out of it. For instance, as demonstrated in this video by [Floyd Steinberg], you can turn it into a fully contained portable device by adding a touchscreen. That incarnation is available from Makerfabs, and it’s a bargain, especially considering that the developer [Brian Whitman] gets some of the proceeds. Or, because it’s written in portable Python, you can run it on your desktop computer for free.

The most interesting part of Tulip for us, as programmer-musicians, is that it boots up into a Micrypython REPL. This is a synth workstation with a command-line prompt as its primary interface. It has an always-running main loop, and you make music by writing functions that register as callbacks with the main loop. If you were fast, you could probably live-code up something pretty interesting. Or maybe it wants to be extended into a physical musical instrument by taking in triggers from the ESP32’s GPIOs? Oh, and did we mention it sends MIDI out just as happily as it takes it in? What can’t Tulip do?

We’ve seen some pretty neat minimalist music-making devices lately, but in a sense Tulip takes the cake: it’s essentially almost entirely software. The various hardware incarnations are just possibilities, and because it’s all open and extremely portable, you can freely choose among them. We really like the design and sound of the AMY software synthesizer engine that powers the Tulip, and we’re sure that more synthesizer models will be written for it. This is a music project that you want to keep your eyes on in the future.

Forget Ship In A Bottle, How About Joule Thief In A Fuse Tube?

August 7, 2024 by 14 Comments

We love close-up pictures of intricate work, and [w] hits the spot with a tiny joule thief in a fuse case (social media post, embedded below) powered by an old coin cell from a watch. It’s so tiny!

Ethernet transformers contain tiny coils.

A joule thief is a sort of minimum-component voltage booster that can suck nearly every last drop of energy from even seemingly-drained batteries, and is probably most famously used to light LEDs from cells that are considered “dead”.

Many joule thief designs feature hand-wound coils, which is great for junk box builds but certainly becomes more of a challenge for a tiny build like this one.

We really like that [w] salvaged a miniscule coil from an Ethernet transformer, most of which look like blocky SMD components from the outside but actually contain tiny coils.

The joule thief has been the basis of plenty of hacks over the years, and it’s always nice to see new twists on the concept.

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The First Real Sputnik

August 7, 2024 by 17 Comments

Americans certainly remember Sputnik. At a time when the world was larger and scarier, the Soviets had a metal basketball flying over the United States and the rest of the world. It made people nervous, but it was also a tremendous scientific achievement. However, it wasn’t the plan to use it as the first orbiter, as [Scott Manley] explains in a recent video that you can see below.

The original design would become Sputnik 3, which, as [Scott] puts it, was the first Soviet satellite that “didn’t suck.” The first one was essentially a stunt, and the second one had an animal payload and thermal problems that killed the canine occupant, [Laika].

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Vintage Crystal Radio Draws The Waves

August 7, 2024 by 10 Comments

The classic crystal radio was an oatmeal box with some wire and a few parts. [Michael Simpson] has something very different. He found an assembled Philmore “selective” radio kit. The simple kit had a coil, a germanium diode, and a crystal earphone.

We were sad when [Michael] accidentally burned a part of the radio’s coil. But–well–in the end, it all worked out. We’ll just say that and let you watch for yourself. The radio is simplicity itself, built on a wooden substrate with a very basic coil and capacitor tuned circuit. Continue reading “Vintage Crystal Radio Draws The Waves” →

FLOSS Weekly Episode 795: Liferay, Now We’re Thinking With Portals

August 7, 2024 by No comments

This week Jonathan Bennett and Doc Searls chat with Olaf Kock and Dave Nebinger about Liferay! That’s a Java project that started as an implementation of a web portal, and has turned into a very flexible platform for any sort of web application. How has this Open Source project turned into a very successful business? And how is it connected to most iconic children’s educational show of all time? Listen to find out!

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Compiling Four Billion If Statements

August 7, 2024 by 44 Comments

With modern tools, you have to try very hard to do something stupid, because the tools (rightly) recognize you’re doing something stupid. [Andreas Karlsson] can speak to that first hand as he tried to get four billion if statements to compile.

You may ask what state space requires four billion comparisons to evaluate? The answer is easy: the range of an unsigned 32-bit integer. The whole endeavor started with a simple idea: what if instead of evaluating whether an integer is even or odd with a modulo or bit mask, you just did an if statement for every case? Small ranges like 0-10 are trivial to write out by hand, but you reach for more automated solutions as you pass 8 bits and move towards 16. [Andreas] wrote some Python that outputs a valid C program with all the comparisons. For 16 bits, the source only clocks in at 130k lines with the executable less than 2 MB.

Of course, scaling to 32 bits is a very different problem. The source file balloons to 330 GB, and most compilers barf at that point. Undeterred, [Andreas] modified the Python to output x86_64 assembly instead of C. Of course, the executable format of Windows (PE) only allows executables up to 4 GB, so a helper program mapped the 40 GB generated executable and jumped into it.

What’s incredible about this whole journey is how performant the program is. Even large numbers complete in a few seconds. Considering that it has to thrash 40 GB of an executable through memory, we can’t help but shake our heads at how even terrible solutions can work. We love seeing someone turn a bad idea into an interesting one, like this desoldering setup.