While at the Hacker Hotel camp in the Netherlands back in February, our attention was diverted to an unusual project. [Niklas Fauth] had bought along a Tesla coil, but it was no ordinary Tesla coil. Instead of the usual tall coil and doughnut-shaped capacity hat it took the form of a stack of PCBs with spacers between them, and because Tesla coils are simply cooler that way, he had it playing music as an impromptu MIDI-driven plasma-ball lousdpeaker. Now he’s been able to write up the project we can take a closer look, and it makes for a fascinating intro not only to double-resonant Tesla coils but also to Galium Nitride transistors.
The limiting factor on Tesla coils comes from the abilities of a transistor to efficiently switch at higher frequencies. Few designs make it above the tens of kHz switching frequencies, and thus they rely on the large coils we’re used to. A PCB coil can not practically have enough inductance for these lower frequencies, thus Niklas’ design employs a very high frequency indeed for a Tesla coil design, 2.6 MHz with both primary and secondary coils being resonant. His write-up sets out in detail the shortcomings of conventional MOSFETS and bipolar transistors in this application, and sets out his design choices in using the GaN FETs. The device he’s using is the TI LMG5200 GaN half-bridge driver, that includes all the necessary circuitry to produce the GaN FET’s demanding drive requirements.
The design files can be found in a GitHub repository, and you can see a chorus of three of them in action in the video below. Meanwhile [Niklas] is a prolific hardware hacker whose work has appeared on these pages in the past, so take a look at his ultrasonic phased array and his x-ray image sensor work.
Continue reading “A Tesla Coil From PCBs”
The Korg DW-6000 is an entry-level synthesiser from the mid 1980s that has the classic sounds, but not enough of them. At least that was [Mateusz Kolanski]’s view, as he hacked his model with a 16-fold increase in its wavetable memory.
At the heart of the DW-6000 is NEC’s UPD7810 16-bit microcontroller, a device stuffed with ports aplenty. The Korg doesn’t use all of those ports, so he was curious as to whether its relatively small 256 kbit ROMs could be upgraded to something much bigger with the use of four unused lines to drive their addresses. This proved to be no easy task, not least because the UPD7810 is hardly a chip with a lot of published work to learn from. A manual for it came from an unexpected source: an obscure game console used it so there is support within MAME.
A significant quantity of hardware reverse engineering and software experimenting later, and he had a ROM piggyback board to plug into his lightly-modified DW-6000. The initial model used stripboard, but naturally a decent PCB was created. That might be everything, but of course some means of working with those samples was required. Enter a Windows wavetable editor and organiser to create new ROM images, for the complete DW-6000 upgrade kit.
This project took several years, proving that persistence can pay off. If you’re not used to the way microcontrollers did their interfacing back in the 1980s then it’s definitely worth a read even if old synths aren’t your thing.
This isn’t the first bit of Korg reverse engineering we’ve brought you, either.
Only 80s kids will remember actual hair metal with the meedley-mees way up high on the fret board, and in the 80s, fret boards got longer. Twenty one or twenty two frets on a guitar weren’t good enough, and you needed the full two octaves of twenty four frets. As with anything, more is better, so [Said Too Much] decided to add frets to his guitar. Yes, you can do that, and it actually doesn’t sound too bad, all things considering.
A few things to cover before going over this build. This did not start out as an experiment to extend the fretboard of a guitar. This started out as a soprano guitar build; this would be the inverse of a baritone guitar — instead of an extended scale length and heavier strings to play a fourth or fifth below a regular guitar, this soprano guitar would have a shorter scale length and lighter gauge strings to play a fourth or fifth above a regular guitar. After a few calculations and some calls to companies that make very, very thin guitar strings, this project morphed into a 3/4 scale guitar (a 23″ scale length, although I question that scale length being actually 3/4 scale) and a set of strings that used 0.07″ strings.
Since a soprano guitar is pretty much just like a normal guitar with more frets, this project also got an extended, 3D printed fretboard. Why? Because. The stock pick guard was modeled and printed out in PLA, removing the neck and middle pickups. Then, an ‘extended fret board adapter’ of sorts was slotted in behind the strings. This gives the guitar 38 frets, a full third of them being printed in PLA.
The burning question: does a 3D printed fret board work? Yes, kind of. If you can get your fingers in between the frets, you can absolutely play the 36th fret on this guitar. It’s not for everybody, obviously, and PLA printed frets will never be as good as polished metal frets. But it is an interesting experimental technique for stringed instruments we haven’t seen before. Check out the video below.
Continue reading “Thirty Six Frets For A 3D Printed Guitar”
The common magnetic loudspeaker is, fundamentally, a fairly simple machine. A static magnetic field is generated by a permanent magnet, and a membrane is mechanically connected to a coil. When a varying electrical current is passed through the coil, this causes the coil to move due to the magnetic field, vibrating the membrane and producing sound. [Mattosx] put this theory into practice with a simple 3D-printed speaker.
It’s not the first 3D-printed speaker we’ve ever seen, but it’s one of the cutest. The main body of the speaker is rectangular, and has a cavity in which three neodymium magnets are placed. The vibrating membrane is then printed separately, including an integrated spindle upon which the coil is wound. The assembly is held together with some socket-head cap screws which complement the pleasantly modern look.
The device does a good job delivering the bleeps when hooked up to an Arduino, and we could see this basic design serving well in all manner of charming 3D-printed builds. Video after the break.
Continue reading “A Mostly 3D Printed Speaker”
This goes back to Bach: if you want to change the sound an organ makes, you have to pull on some drawbars. This design didn’t change for 300 years, and in the 20th century with the advent of ‘tonewheel’ organs, you still had small bars to pull to change what sounds came out of the organ. While this was a simple solution for air-powered organs of the 1700s, when it comes to MIDI, rotary pots are a lot less expensive than linear pots. Given the lack of drawbar MIDI controllers, [Stefano] decided to build his own. It has nine drawbars and eight buttons, all connected to MIDI.
The interesting electromechanical part of this build, the drawbars themselves, are ripped from a Hammond organ. Don’t worry, plenty of these were made and only a handful actually sound good. To that, [Stefano] added a few pushbuttons soldered onto a piece of perfboard, and everything is wired up to a Teensy LC, the microcontroller platform that’s becoming the standard for everything from MIDI controllers to computer keyboards. MIDI over DIN and MIDI over USB are supported, and all the buttons and drawbars are individually programmable. You can even do that through SysEx messages, because that’s how things were done back in the day.
While there are a few MIDI-controlled organs that still use drawbars — the double manual Nord comes to mind imminently — this is a great solution to putting drawbars into anything that speaks MIDI, VSTs included.
Pickups are a key part of an electric guitar’s sound. You can spend a king’s ransom on tracking down just the right Vintage American Original 1950s Whatevers (TM) to put in your Spudocaster, but it’s not the only way. [Keith Decent] decided to make a pickup from scratch, using only materials found lying around the workshop. (Youtube, embedded below).
To build a pickup, you’ll want some magnet wire. In this case, [Keith] harvests this from an old transformer. A pickup body is then constructed from an old wooden ruler and some machine screws. A drill is used to spin the pickup body while the wire is roughly wound on, and everything is then held together with lashings of hot glue.
It’s a grungy build with a very Mad Max vibe – with the perfect aesthetic to suit [Keith]’s junkbox guitar build. The sound is good, but difficult to rate accurately when used on a guitar with slightly imperfect intonation. We’d love to hear it installed on a well-tuned body to get a better comparison.
It goes to show you don’t need to spend money on new parts and tools to get a build started. Sometimes you can make something perfectly functional with stuff you have lying around at home. Video after the break.
Continue reading “Building Your Own Guitar Pickup From Scrap”
All the best retro-1980s chiptune acts should possess a keytar. It’s the Law, or something. [Theremin Hero] has reminded us of this with a new video we’ve shown below featuring an instrument he had a part in creating alongside [Sam Wray] and [Siddharth Vadgama] a few years ago. The Blade is a 3D-printed keytar featuring two Guitar Hero necks and an integrated pair of Game Boys to provide the sound from the authentic silicon.
To describe it in those terms though is to miss a wealth of other components and featured. The keyboard itself is from a Rock Band keytar which feeds MIDI to a Raspberry Pi running PD Extended that handles all the button press mappings. An Arduino Mega performs the same task for the two Guitar Hero necks. Midi from the various sources is processed by an Arduino Boy which then feeds the Game Boys that make the sounds. Oh – and there’s a Leap Motion 3D motion controller in the mix as well, though that doesn’t seem to be used directly in the chiptune synth functionality.
We’ve had a few keytars here over the years, but this one makes us think of the Commodore 64 instrument created by [Jeri Ellsworth].
Continue reading “It’s (Almost) Two Keytars In One!”