The laser driver's internals, showing the custom PCB, the PSU, connectors and the interlocks.

Laser Driver Design Keeps Safety First

May 29, 2022 by 20 Comments

[Les] from [Les’ Lab] has designed a driver for laser diodes up to 10 watts, and decided to show us how it operates, tells us what we should keep in mind when designing such a driver, and talks about laser safety in general. This design is an adjustable current regulator based on the LM350A, able to provide up to 10 watts of power at about 2 volts – which is what his diode needs. Such obscure requirements aren’t easily fulfilled by commonly available PSUs, which is why a custom design was called for.

He tells us how he approached improving stability of the current regulation circuit, the PCB design requirements, and planning user interface for such a driver. However, that’s just part of the battle – regulating the current properly is important, but reducing the potential for accidental injuries even more so. Thus, he talks extensively about designing the driver circuit with safety in mind – using various kinds of interlocks, like a latching relay circuit to prevent it from powering up as soon as power is applied.

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Relax And Enjoy This Simple Drone Synthesizer

May 29, 2022 by 2 Comments

You’d think that a synthesizer that makes as much noise and sports as many knobs as this one would have more than a dozen transistors on board. Surely the circuit behind the panel is complex, and there must be at least a couple of 555 timers back there, right?

But no, the “Box of Beezz” that [lonesoulsurfer] came up with is remarkably simple. It takes inspiration from a [Look Mum No Computer] circuit called the “Circle Drone of Doom,” which used six switchable relaxation oscillators to make some pretty cool sounds. The Box of Beezz steps that up a bit, with four oscillators in three switchable banks in the final version. Each oscillator has but one transistor with a floating base connection and a simple RC network on the collector. The sawtooth outputs of these relaxation oscillators can be adjusted and summed together, resulting in some surprisingly complex sounds. Check out the video below for a bit of the synth’s repertoire — we’d swear that there are points where we can hear elements of the THX Deep Note in there.

We poked around a bit to understand these oscillators, and it looks like these qualify as avalanche relaxation oscillators. [lonesolesurfer]’s notes indicate that SS9018 transistors should be used, but in the photos they appear to all be 2N4401s. We’re not sure how long the transistors will last operating in the avalanche mode, but if they quit, maybe some neon tubes would work instead.

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Better Robots Through Gallium

May 29, 2022 by 16 Comments

In the movie Terminator 2, the T-1000 robot was made of some kind of liquid metal that could change shape among other interesting things. According to a chemical engineer at North Carolina State University, there may be something to the idea. [Michael Dickey] has been experimenting with gallium, a liquid metal, that scientists think may unlock a new generation of flexible devices.

The most common liquid metal is mercury, of course, and it has its uses. However, its toxicity has led to a reduction in its use. Gallium has low toxicity and also doesn’t easily evaporate. What can you do with it? Check out the video below to see a very simple demonstration of the liquid metal lifting a small — very small — weight with an electrical impulse.

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The LackRack Enterprise Edition in Revspace, Netherlands

Rackmount Hardware Placement Issues? IKEA LACK To The Rescue!

May 29, 2022 by 18 Comments

[hackbyte] reminds us about a classic hack that, even though we’ve seen floating around for over a decade, has somehow never quite graced our pages before. Many of us keep small home labs and even, at times, collections of servers that we’d be comfortable be calling mini-datacenters. However, if you use the ever-abundant 19″ switches, servers and other hardware, keeping these mounted and out of the way can be a thorny experience. Which leads us to, undoubtedly, unintentional – but exceptionally handy – compatibility between IKEA LACK table series and 19″ rackmount hardware.

The half-humorous half-informative wiki page on Eth0Wiki talks about this idea in depth, providing a myriad of examples and linking to pages of other hackerspaces and entities who implemented this idea and improved upon it. These tables look nice and fit anywhere, stack neatly when not in use, and you can put a bottle of Club-Mate on top. Aka, they’re the exact opposite of cheap clunky cabinets actually designed for rackmount you can buy, and cost a fraction of the price. What’s not to love?

You can buy a whole lot of cheap hardware in 19″, and arguably, that’s where you can get the best hardware for your dollar. Many a hackerspace has used these tables for makeshift infrastructure, permanent in all but intent. So, in case some of us missed the memo, now you are aware of yet another, underappreciated solution for mounting all these servers we get for cheap when yet another company replaces its equipment – or undergoes a liquidation. If LackRack hasn’t been on your radar – what have you been using for housing your rackmount hardware collection?

Wondering what to do with an old server? Building a powerful workstation is definitely on the list. Alternatively, you could discard the internals and stuff it full of Raspberry Pi!

Annotate PDFs On Linux With PDFrankenstein

May 28, 2022 by 20 Comments

On Windows and Mac machines, it’s not too troublesome to add text or drawings (such as signatures) to PDF files, but [Mansour Behabadi] found that on Linux machines, there didn’t seem to be a satisfying way or a simple tool. Being an enterprising hacker, [Mansour] set out to fill that gap, and the way it works under the hood is delightfully hacky, indeed.

The main thing standing in the way of creating such a tool is that the PDF format is a complex and twisty thing. Making a general-purpose PDF editing tool capable of inserting hyperlinks, notes, images, or drawings isn’t exactly a weekend project. But [Mansour] didn’t let that stop him; he leveraged the fact that tools already exist on Linux that can read and create PDF files, and tied them all together into what was at one point “a horrific patchwork of tools” which inspired the name pdfrankenstein.

The tool is a GUI that uses Inkscape and qpdf to convert a PDF page to an SVG file, set it as a locked background, then let the user add any annotations they desire, using Inkscape as the editor. After changes are made, the program removes the background, overlays the annotations back onto the originals, and exports a final file. Annotations can therefore be anything that can be done in Inkscape.

Curious about these and other tools for handling PDFs? We’ve shared some programs and tricks when we previously covered dealing with the PDF format in Linux.

Soap Mouse Is A Slippery Interface For Mid-Air Input

May 28, 2022 by 5 Comments

We all have those gnarly hacks that we still think about years after we first saw them. For serial tipster [Inne], one of those is [Patrick Baudisch]’s soap mouse, which is a DIY device for mousing in mid-air that uses components from off the shelf and around the house.

How does it work? The guts are encased in plastic shaped like a flattened pill, which slips into a fuzzy sock. By squeezing it a bit, the plastic pill rotates, spinning the outward-facing sensor round and round. Although we briefly reported on the soap mouse way back in 2006, we think it deserves to be in the spotlight today, especially since there’s a complete PDF guide to building one that’s optimized for gaming. If you want a regular pointing device instead, the conversion is described within.

[Patrick] uses a CompUSA (RIP) mouse in the guide, but any sufficiently slim and also short mouse should work as long as it has a decently long focal range, which is necessary for the sensor to see the hull. Plenty of travel mice out there should fit the bill.

The hull itself is made from two small (empty) bottles of hand sanitizer, chosen for their size, shape, and clarity of plastic. The outermost housing is a baby sock with a snap sewn on. [Patrick] says moving the sock against the plastic is difficult, and has tried various methods for lubrication, such as a bit of mineral oil inside some plastic bags.

Be sure to check out the video after the break, which does a great job of explaining everything from the various types of interaction to construction in 5½ minutes.

Since 2006, [Patrick] has held workshops where people have built their own soap mice. Have you built one? Let us know in the comments. And don’t forget about the Digi-Key-sponsored Odd Inputs and Peculiar Peripherals contest, which runs through July 4th. Declare your independence from regular keyboards and mice and win big!

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AI Attempts Converting Python Code To C++

May 28, 2022 by 31 Comments

[Alexander] created codex_py2cpp as a way of experimenting with Codex, an AI intended to translate natural language into code. [Alexander] had slightly different ideas, however, and created codex_py2cpp as a way to play with the idea of automagically converting Python into C++. It’s not really intended to create robust code conversions, but as far as experiments go, it’s pretty neat.

The program works by reading a Python script as an input file, setting up a few parameters, then making a request to OpenAI’s Codex API for the conversion. It then attempts to compile the result. If compilation is successful, then hopefully the resulting executable actually works the same way the input file did. If not? Well, learning is fun, too. If you give it a shot, maybe start simple and don’t throw it too many curveballs.

Codex is an interesting idea, and this isn’t the first experiment we’ve seen that plays with the concept of using machine learning in this way. We’ve seen a project that generates Linux commands based on a verbal description, and our own [Maya Posch] took a close look at GitHub Copilot, a project high on promise and concept, but — at least at the time — considerably less so when it came to actual practicality or usefulness.