Build Your Own Class-E Musical Tesla Coil

We’ve all seen a million videos online with singing Tesla coils doing their thang. [Zach Armstrong] wasn’t content to just watch, though. He went out and built one himself! Even better, he’s built a guide for the rest of us, too!

His guide concerns the construction of a Class-E solid state Tesla coil. These are “underrated” in his opinion, as they’re simple, cheap, and incredibly efficient. Some say up to 95% efficient, in fact! It’s not something most Tesla coil fans are concerned with, but it’s nice to save the environment while making fun happy sparks, after all.

[Zach]’s guide doesn’t just slap down a schematic and call it good. He explains the theory behind it, and the unique features too. He uses an adjustable Schmitt trigger oscillator for the build, and he’s naturally given it an audio modulation capability because that’s a good laugh, too.

If you’ve ever wanted to convince you’re friends you’re incredibly smart and science-y, you can’t go wrong with a singing Tesla coil. This beats out Jacob’s ladder and most other plasma experiments for sheer mad scientist cred.

Have fun out there! Video after the break.

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Flute Now Included On List Of Human Interface Devices

For decades now, we’ve been able to quickly and reliably interface musical instruments to computers. These tools have generally made making and recording music much easier, but they’ve also opened up a number of other out-of-the-box ideas we might not otherwise see or even think about. For example, [Joren] recently built a human interface device that lets him control a computer’s cursor using a flute instead of the traditional mouse.

Rather than using a MIDI interface, [Joren] is using an RP2040 chip to listen to the flute, process the audio, and interpret that audio before finally sending relevant commands to control the computer’s mouse pointer. The chip is capable of acting as a mouse on its own, but it did have a problem performing floating point calculations to the audio. This was solved by converting these calculations into much faster fixed point calculations instead. With a processing improvement of around five orders of magnitude, this change allows the small microcontroller to perform all of the audio processing.

[Joren] also built a Chrome browser extension that lets a flute player move a virtual cursor of sorts (not the computer’s actual cursor) from within the browser, allowing those without physical hardware to try out their flute-to-mouse skills. If you prefer your human interface device to be larger, louder, and more trombone-shaped we also have a trombone-based HID for those who play the game Trombone Champ.

Cyberpunk Guitar Strap Lights Up With Repurposed PCBs

Sometimes, whether we like it or not, ordering PCBs results in extra PCBs lying around, either because of board house minimums, mistakes on either end, or both. What’s to be done with these boards? If you’re Hackaday alum [Jeremy Cook], you make a sound-reactive, light-up guitar strap and rock out in cyberpunk style.

The PCBs in question were left over from [Jeremy]’s JC Pro Macro project, and each have four addressable RGB LEDs on board. These were easy enough to chain together with jumper wires, solder, and a decent amount of hot glue. Here’s a hot tip: you can use compressed air to rapidly cool hot glue if you turn the can upside down. Just don’t spray it on your fingers.

The brains of this operation is Adafruit Circuit Playground Express, which runs off of a lipstick battery and conveniently brings a microphone to the table. These two are united by a 3D print, which is hot-glued to the guitar strap along with all the boards. In the second video after the break, there’s a bonus easy-to-make version that uses an RGB LED strip in place of the repurposed PCBs. There’s no solder or even hot glue involved.

Want to really light up the night? Print yourself a sound-reactive LED guitar.

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Building A Tape Echo In A Coke Can Tape Player That Doesn’t Really Work

Back in the 1990s, you could get a tape player shaped like a can of Coca Cola. [Simon the Magpie] scored one of these decks and decided to turn it into a tape echo effect instead. It didn’t work so well, but the concept is a compelling one. You can see the result in the video below.

The core of the effect is a tape loop, which [Simon] set up to loop around a pair of hacked-up cassette shells. This allows him to place one half of the loop in the Coca-Cola cassette player and the other half in a more conventional desktop tape deck. A 3D-printed bracket allows the two decks and the tape loop to be assembled into one complete unit.

The function is simple. The desktop tape deck records onto the loop, with the Coca-Cola unit then playing back that section of tape a short while later. Hey, presto — it’s a tape delay! It’s super lo-fi, though, and the tape loop is incredibly fragile.

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Make Your Music Simpler With The User-Unfriendliest Cassette Deck Ever

Call us crazy, but music was a whole lot more fun when it was on physical media. Or perhaps just easier to use, especially in the car. Whether your particular vintage favored CDs, cassettes, or even 8-tracks, being able to fish out that favorite album and slam it in the player while never taking your eyes off the road was a whole lot easier than navigating a playlist on a locked phone, or trying to control an infotainment system through soft buttons on a touch screen.

It seems like [Jarek Lupinski] is as much a Spotify Luddite as we are, since his “tape-deck” project is aimed to be as user-unfriendly as possible. It’s just an auto-reversing cassette deck movement stripped bare of all useful appurtenances, like a way to fast forward or rewind. You just put a cassette in and it plays, start to finish, before auto-reversing to play the other side in its entirety. It doesn’t even have a volume control — his cheeky advice is to “listen to louder or quieter albums” to solve that problem. Pretty easy, really, and not a EULA or advertisement in sight. Build files are available if you hate yourself enough to build one of your own.

All kidding aside, this is kind of a nice reminder of how much things have changed, and how much complexity we’ve layered onto the simplest of pleasures. If you like the minimalist approach of this project but not the deconstructed aesthetics, we’ve got you covered.

The board in question, with a Pi Pico soldered on, with old PCBs for macropads being used as captouch electrodes

Give Your Pi Pico Captouch Inputs For All Your Music Needs

Unlike many modern microcontrollers, RP2040 doesn’t come with a native capacitive touch peripheral. This doesn’t mean you can’t do it – the usual software-driven way works wonderfully, and only requires an external pullup resistor! In case you wanted a demonstration or you have a capacitive touch project in mind, this lighthearted video by [Jeremy Cook] is a must watch, and he’s got a healthy amount of resources for you in store, too!

In this video, [Jeremy] presents you with a KiCad schematic and an PCB design you can use to quickly add whole 23 capacitive touch sensing inputs to a Pi Pico! The board is flexible mechanically, easy to assemble as [Jeremy] demonstrates, and all the pins involved can still be used as regular GPIOs if you’d like. Plus, it’s fully open-source, can easily be assembled on your own, and available on Tindie too!

Of course, such a board doesn’t get created for no reason – [Jeremy] has a healthy amount of musical creations and nifty ideas to show off. We quite liked the trick of using old PCBs as capacitive touch sensing, using copper fills as electrodes – which has helped create an amusing “macropad of macropads”, and, there’s quite a bit more to see.

If capacitive touch projects ever struck a chord with you and you enjoy music-related hacking, [Jeremy]’s got a whole YouTube channel you ought to check out. Oh, and if one of the musical projects in the video caught your eye, it might just be the one we’ve featured previously! Continue reading “Give Your Pi Pico Captouch Inputs For All Your Music Needs”

Documenting Real Hidden Messages In Music

During the 1980s, a moral panic swept across the landscape with the mistaken belief that there were Satanic messages hidden in various games, books, and music that at any moment would corrupt the youth of the era and destroy society as we knew it. While completely unfounded, it turns out that there actually were some hidden messages in vinyl records of the time although they’d corrupt children in a different way, largely by getting them interested in computer science. [Dandu] has taken to collecting these historic artifacts, preserving the music and the software on various hidden recordings.

While it was possible to record only programs or other data to vinyl, much in the same way that cassette tapes can be used as a storage medium, [Dandu]’s research focuses mostly on records, tapes, and CDs which had data included alongside music. This includes not only messages or images, but often entire computer programs. In some cases these programs were meant to be used with the accompanying music, as was the case for The Other Side Of Heaven by Kissing The Pink with a program for the BBC Micro. Plenty of other contemporary machines are represented here too including the ZX Spectrum, Atari, Apple II, and the Commodore 64. The documentation extends through the CD era and even into modern music platforms like Spotify and Apple Music.

The process of extraction and recovery is detailed for each discovery, making it a comprehensive resource for retro computing enthusiasts stretching from the 80s to now. There are likely a few hidden pieces of data out there hidden in various antique storage media that [Dandu] hasn’t found yet, either. You could even make your own records with hidden programs provided you have some musical and programming talents, and a laser engraver for the record itself.