A troublesome Triple-Z80 arcade board requires negative voltage for audio output

Vintage Arcade Used Negative Voltage To Turn Volume Up To 11

October 27, 2021 by Ryan Flowers 50 Comments

When [Nicole Express] got her hands on the logic board for the 1986 SNK arcade game Athena, she ran into a rather thorny problem: The board expected to be fed negative five volts! [Nicole]’s analysis of the problem and a brilliant solution are outlined in her well written blog post.

[Nicole]’s first task was to find out which devices need negative voltage. She found that the negative five volts was being fed through a capacitor to the ground pins on the Mitsubishi M151516L, an obscure 12 W audio amplifier. After finding the data sheet, she realized something strange: the amp didn’t call for negative voltage at all! A mystery was afoot.

To fully understand the problem, she considered a mid-1980’s arcade and its cacophony of sounds. How would a manufacturer make their arcade game stand out? By making it louder, obviously! And how did they make their game louder than the rest?

The answer lays in the requirement for negative five volts. The amplifier is still powered with a standard 12 V supply on its VCC pin. But with ground put at -5 V, the voltage potential is increased from 12 V to 17 V without overpowering the chip. The result is a louder game to draw more players and their fresh stacks of quarters.

How was [Nicole Express] to solve the problem? ATX PSU’s stopped providing -5 V after the ISA slot disappeared from PC’s, so that wouldn’t work. She could have purchased an expensive arcade style PSU, but that’s not her style. Instead, she employed a wonderful little hack: a charge pump circuit. A charge pump works by applying positive voltage to a capacitor. Then the capacitor is quickly disconnected from power, and the input and ground are flipped, an equal but negative voltage is found on its opposite plate. If this is done with a high enough frequency, a steady -5 V voltage can be had from a +5 V input. [Nicole Express] found a voltage inverter IC (ICL7660) made just for the purpose and put it to work.

The IC doesn’t supply enough power to get 12 W out of the amplifier, and so the resulting signal is fed into an external amplifier. Now [Nicole]’s arcade game has sound and she can play Athena from the original arcade board, 1986 style!

Arcades are few and far between these days, but that doesn’t mean you can’t introduce your young ones to the joys of dropping a quarter or two, or build a gorgeous oak Super Mario Bros cabinet complete with pixel art inlays. Do you have a favorite hack to share? Be sure let us know via the Tip Line!

Simple Electronic Hacks Inspire Doing More With Less

October 26, 2021 by Ryan Flowers 18 Comments

It’s late at night. The solder smoke keeps getting in your tired eyes, but your project is nearly done. The main circuit is powered by your 13.8 V bench supply, but part of the circuit needs 9 V. You dig into your stash to find your last LM7809 voltage regulator, but all you have is a bunch of LM7805’s. Are you done for the night? Not if you’ve watched [0033mer]’s Simple Electronic Circuit Hacks video! You know just what to do. The ground pin of a LM7805 connects to the cathode of a TL431 programmable Zener diode pulled from an old scrapped TV. The diode is referenced to a voltage divider, and voila! Your LM7805 is now putting out a steady 9 V.

How did [0033mer] become adept at doing more with less? As he explains in the video below, his primary source of parts in The Time Before The Internet was old TV’s that were beyond repair. Using N-Channel MOSFETs to switch AC, sensing temperature changes with signal diodes, and even replacing a 555 with a blinking LED are just a few of the hacks covered in the video below the break.

We especially appreciated the simple, to-the-point presentation that inspires us to keep on hacking in the truest sense: Doing more with less! If you enjoy a good diode hack like we do, you will likely appreciate learning Diode Basics by W2AEW, or a Diode Based Radiation Detector.

Thank you [DSM] for the tip! Be sure to submit your the cool things you come across to our Tips Line!

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Surfsonar shows the depth of water while surfing

Surf Sensor Adds Depth To Finding The Ultimate Wave

October 25, 2021 by Ryan Flowers 9 Comments

To say that the ocean is a dynamic environment would be a gross understatement, especially when coastlines are involved. Waves crash, tides go in and out, and countless variables make even the usual conditions a guessing game. When [foobarbecue] goes surfing, he tries to take into account all of these things. The best waves at his local beach are directly over an ever-moving sand bar, and their dynamics are affected by depth, another constant variable. [foobarbecue]’s brilliant solution to understanding current conditions? Build a depth finder directly into his surf board!

At the heart of the “surfsonar” is the Ping Sonar Echosounder, a sonar transducer designed for AUV’s and ROV’s. [foobarbecue] embedded the transducer directly into the board. Data is fed to a Raspberry Pi 4b, which displays depth and confidence (a percentage of how sure it is of the measurement) on a 2.13 inch e-Paper Display Hat.

Power is provided by a PiSugar. Charging is done wirelessly, which we’d say is pretty important considering that the whole device is sealed inside a modified surfboard.

While it’s not a low budget build, and there’s yet room for improvement, early reports are positive. Once away from the breaking waves, the device confidently shows the depth. More testing will show if the surfsonar will help [foobarbecue] find that ever-moving sandbar!

Surf hacks are always welcome, we’ve featured the LED Strip Lit Surfboard as well as the Surf Window, which tells its owner if the surf is up. Be sure to let us know about any cool hacks you find when you’re out surfing the ‘net via our Tips Line!

Tricky Screw Heads Have Disappearing Slots

October 24, 2021 by Ryan Flowers 51 Comments

Perhaps you’ve seen them, demonstrations of a machined piece of metal that upon further inspection is actually two pieces machined so perfectly that they appear as one. With extremely tight tolerances, it’s not possible to determine where one piece of metal ends and another begins — that is, until the secret is revealed. Inspired by such pieces of art, [Andrew Klein] sought to put this high level of machine work to practical use. And so it was that his as-yet-unnamed Screw With No Slot came to be.

Klein Hidden Bolt depressed by brass rod — A brass rod pushes down to reveal the keyed center section.

The screw’s disc-like appearance looks as if it’s a metal trim piece to cover a bolt hole. But in the video below [Andrew] shows us the trick, pushing a brass rod into the middle of the disc to reveal the hidden three-point slot. The center of the disk is actually a separate bit of finely machined metal that is spring loaded to stay flush. A specially designed wrench keys into the rounded concave triangle shape cut into the face.

The wrench is made with brass to avoid marring the precision surface. It uses three magnets to hold tight to the screw’s 410 magnetic stainless steel. [Andrew] didn’t spill the beans on how this was done, but we haven’t seen any process other than electrical discharge machining (EDM) that can achieve this level of mating precision. If that topic is new to you, we recommend checking out [Ben Krasnow’s] lab experiments on the topic.

We can’t help but be taken in by the beauty of the fastener, and it immediately sent our imaginations into a National Treasure induced dream-like state. [Andrew Klein] has yet to name this fastener, and he’s soliciting ideas for names in the video below the break. If you have such an idea, you can comment on his video. He’s also exploring the viability of the as-yet-named fastener as a commercial product for high end furniture builders.

This is not the first time we’ve featured [Andrew Klein]’s work. His previous featured projects include a custom sawblade for perfectly foldable joints and an unveiling of the magnetic magic behind switchable permanent magnets. Be sure to submit the neat hacks, builds, and inspiring projects that you come across to our Tip Line!

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Supply Chain Attack: NPM Library Used By Facebook And Others Was Compromised

October 22, 2021 by Ryan Flowers 26 Comments

Here at Hackaday we love the good kinds of hacks, but now and then we need to bring up a less good kind. Today it was learned that the NPM package ua-parser-js was compromised, and any software using it as a library may have become victim of a supply chain attack. What is ua-parser-js and why does any of this matter?

In the early days of computing, programmers would write every bit of code they used themselves. Larger teams would work together to develop larger code bases, but it was all done in-house. These days software developers don’t write every piece of code. Instead they use libraries of code supplied by others.

For better or worse, repositories of code are now available to do even the smallest of functions so that a developer doesn’t have to write the function from scratch. One such registry is npm (Node Package Manager), who organize a collection of contributed libraries written in JavaScript. One only need to use npm to include a library in their code, and all of the functions of that code are available to the developer. One such example is ua-parser-js which is a User Agent Parser written in JavaScript. This library makes it easy for developers to find out the type of device and software being used to access a web page.

On October 22 2021, the developer of ua-parser-js found that attackers had uploaded a version of his software that contained malware for both Linux and Windows computers. The malicious versions were found to steal data (including passwords and Chrome cookies, perhaps much more) from computers or run a crypto-currency miner. This prompted GitHub to issue a Critical Severity Security Advisory.

What makes this compromise so dangerous is that ua-parser-js is considered to be part of a supply chain, and has been adopted even by Facebook for use in some of its customer facing software. The developer of ua-parser-js has already secured his GitHub account and uploaded new versions of the package that are clean. If you have any software that uses this library, make sure you’ve got the latest version!

Of course this is by no means a unique occurrence. Last month Maya Posch dug into growing issues that come from some flaws of trust in package management systems. The art for that article is a house of cards, an apt metaphor for a system that is only as stable as the security of each and every package being built upon.

ddrysfeöd circuit art sound and light scultpture

Labyrinthian Circuit Sculpture Evokes Moods With Sound And Light

October 20, 2021 by Ryan Flowers 5 Comments

In a famous letter penned by Victorian era author Oscar Wilde, he wrote:

“Art is useless because its aim is simply to create a mood. It is not meant to instruct, or to influence action in any way. It is superbly sterile, and the note of its pleasure is sterility.”

We can’t help but wonder if [Eirik Brandal] was evoking such Wilde thoughts when he wrote to tell us about ddrysfeöd, an electronic sound and light sculpture which he called “uselessly applied electronics.” Given the mood created by the video below the break, we have to agree that it is indeed quite artful. But if it serves a purpose to inspire and cause wonderment, is it really useless? Let the philosophers philosophize. On to the hack!

[Eirik] was himself inspired by mazes such as those found in children’s activity books and magazines whose goal is to keep a child ~~busy~~ challenged by drawing a solid line from start to finish. With these in mind, [Eirik] constructed ddrysfeöd as an intricate entanglement of electronics, metal, clear and mirrored acrylic, and plated steel, all flung into a three dimensional vortex.

LED’s of red and white oscillate in time with each other. Orchestrating the multimedia symphony is an ESP32, with one core relegated to dealing with the mundane functions of the sculpture while the other waves its electronic wand to keep the ensemble suitably arranged. LED’s are bored into the base, and the acrylic is sanded on the edges to diffuse the supplied light. The electronics run on the usual +5 V, but a +12 V power supply gives volume to the LM380 audio amplifier. We also appreciated that [Eirik] expanded his skills on this project by using Sketchup to plan out the project, even printing the patterns for cutting and drilling the acrylic glass.

If [Eirik]’s build style looks familiar, it may be because you’ve seen it here on Hackaday’s Circuit Sculpture Contest, where some of his work was named Most Beautiful. You can also feast your eyes on a BEAM bot inspired pummer in the shape of a satellite. And remember, if you run across something that presses your buttons, let us know via the Tip Line!

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Art Project Fast And Fouriously Transforms Audio Into Eye Candy

October 14, 2021 by Ryan Flowers 2 Comments

Fast Fourier Transforms. Spectrum Analyzers. Waterfall displays. Not long ago, such terms were reserved for high end test gear. But oh, how things have changed! It’s no surprise to many Hackaday readers that modern microcontrollers have transformed the scene as they become more powerful and as a result are endowed with more and more powerful software libraries. [mircemk] has used such a library along with other open source software combined with mostly off the shelf hardware to create what he calls the DIY FFT Spectrum Analyzer. Rather than being a piece of test gear, this artful project aims to please the eye.

The overall build is relatively simple. Audio is acquired via a line-in jack or a microphone, and then piped into an ESP32. The ESP32 runs the audio through the FFT routine, sampling, slicing, and dicing the audio into 16 individual bands. The visual output is displayed on a 16 x 16 WS2812 Led Matrix. [mircemk] wrote several routines for displaying the incoming audio, with a waterfall, a graph, and other visualizations that are quit aesthetically pleasing. Some of them are downright mesmerizing! You can see the results in the video below the break.

Of course the build doesn’t stop with slapping some hardware and a few passive components together. To really be finished, it needs to be encased in something worth displaying. [mircemk] does not disappoint, as a beautiful 3D-printed enclosure wraps it all up nicely.

We think that the final product is great, and it reminds us of some of the very things that inspired us early on in our hacking careers. We would love to see this project integrated with an Interactive Musical Art Installation of any kind, the more esoteric the better. Perhaps a 555 timer synth could fit the bill? Be sure to share your own hacks with us via the Tip Line!

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