Doing MIDI With Discrete Logic Is Neat, If Not Particularly Useful

September 13, 2024 by Lewin Day 4 Comments

MIDI is normally baked into the chipset of a synthesizer, or something you use a microcontroller to handle. But that’s not the only way to speak the language! [Kevin] decided to have some fun doing MIDI with discrete logic instead, with some pretty neat results.

[Kevin] had previously built a control voltage step sequencer called the Baby8, which relied on 4017 counter ICs. He later realized he could repurpose three of his old Baby8 PCBs to create something that could generate MIDI using nothing more than discrete logic. The stack of three boards generate a simple MIDI message—in this case, a two-byte Program Change command. At 8 bits per byte, plus a start and stop bit, that comes out to 20 bits in total. The bits to be sent are configured via the switches on the PCBs, and clocked out through the counter ICs via a clock running at the MIDI baud rate of 31,250 Hz.

Obviously, it’s not very practical to code your MIDI commands manually via DIP switches and then clock them out in this fashion. But—it does work, and you can do it! If you wanted to build an old-school logic circuit that just spits out simple short MIDI commands, this is one way to go about it.

We’ve seen [Kevin]’s work before, too, like this neat musical rotary phone build.

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Simple PCB Agitator Gets The Job Done

September 13, 2024 by Lewin Day 17 Comments

These days, PCB fab houses are just about everywhere, and you can’t go buy a taco without walking past eight of them. Still, some out there still like to etch their PCBs at home. If that sounds like you, you might see some value in [Chris Borge]’s PCB agitator.

The design mostly relies on 3D printed parts, including the main body. It has a heavy base which is filled with concrete to keep it nicely weighed down on the table. A table for holding a PCB and fluid tank is then installed on top, via a bearing which allows it to pivot in one axis. An Arduino Nano commands the agitation of the table top, and hence the PCB etching tank, with a servo used to actually shift the table back and forth.

It’s a simple design — far simpler than some of the advanced coffee-making hardware we’ve seen recently. Regardless, it gets the job done, and done well! In testing, it accelerated [Chris]’s etching jobs significantly, we’re talking hours here. Meanwhile, if you don’t have a 3D printer on hand, you could always try building one out of junk instead!

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There’s Already A Nixie Addon For The 2024 Supercon Badge

September 12, 2024 by Lewin Day No comments

Nixie tubes are cool, and hackers like them. Perhaps for those reasons more than any other, [Kevin Santo Cappuccio] has developed a very particular Simple Add-On for the 2024 Hackaday Supercon badge.

The build began with a Burroughs 122P224 Nixie tube, and a HV8200 power supply. The latter component is key—it’s capable of turning voltages as low as 3 V into the 180V needed to power a Nixie. Then, an 18-position selector switch was pulled out of a resistance substitution box, and [Kevin] whipped up a basic DIY slip ring using some raw copper clad board.

Smoosh it all together, and what do you get? It’s a Nixie tube you can spin to change the number it displays. Useful? Hardly, unless you want to display varying glowing numbers to people at unreadable angles. Neat? Very. Just don’t touch any of the pins carrying 180 V, that’ll sting. Still, [Kevin] told us it’s pretty tucked away. “I’m totally comfortable touching it, but also would get sued into oblivion selling these on Amazon,” he says.

As [Kevin] notes in his post, the 2024 badge is all about the add-ons— and there’s actually a contest! We suspect [Kevin] will have a strong chance of taking out the Least Manufacturable title.

If you need more information about the Simple Add-On (SAO) interface, [Brian Benchoff] posted the V1.69bis standard on these very pages back in 2019. Apparently the S used to stand for something else. Video after the break.

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Back Up Your Data On Paper With Lots Of QR Codes

September 12, 2024 by Lewin Day 59 Comments

QR codes are used just about everywhere now, for checking into venues, ordering food, or just plain old advertising. But what about data storage? It’s hardly efficient, but if you want to store your files in a ridiculous paper format—there’s a way to do that, too!

QR-Backup was developed by [za3k], and is currently available as a command-line Linux tool only. It takes a file or files, and turns them into a “paper backup”—a black-and white PDF file full of QR codes that’s ready to print. That’s legitimately the whole deal—you run the code, generate the PDF, then print the file. That piece of paper is now your backup. Naturally, qr-backup works in reverse, too. You can use a scanner or webcam to recover your files from the printed page.

Currently, it achieves a storage density of 3KB/page, and [za3k] says backups of text in the single-digit megabyte range are “practical.” You can alternatively print smaller, denser codes for up to 130 KB/page.

Is it something you’ll ever likely need? No. Is it super neat and kind of funny? Yes, very much so.

We’ve seen some other neat uses for QR codes before, too—like this printer that turns digital menus into paper ones. If you’ve got your own nifty uses for these attractive squares, let us know!

Digital Bumper Sticker Tells Everyone What You’re Listening To

September 12, 2024 by Lewin Day 23 Comments

Bumper stickers are usually political, crude, or otherwise inflammatory. Rather a more fun example is this digital creation from [Guy Dupont], who made a bumper sticker that broadcasts what he’s listening to on the stereo.

[Guy] found a nice wide 11-inch bar LCD that was the right aspect ratio to suit the “bumper sticker” aesthetic. It had an HDMI interface, so he decided to drive it with a Raspbery Pi Zero 2W. Power for the system was derived from 12-volt lines going to his vehicle’s rear view camera. For an enclosure, he simply stuck the Pi and a buck converter on the back of the display and heat shrinked the whole thing. He also threw some magnets in there to stick it to the car.

How does the screen know what song to display? Well, [Guy] already has his Spotify listens scrobbling to Last.fm. Thus, he just made a script that scrapes his Last.fm page, which runs on a Particle Boron microcontroller, which has a cellular connection of its own. The Boron gets the song data, and spits it over to the Pi via Bluetooth. Then the Pi generates an image for the display.

Oh, and there’s also a neat Easter Egg. In honor of brat summer, the background changes to #8ACE00 green if the system detects you’re listening to Charli XCX. Neat.

It’s a neat build with a lot of moving parts. We’re surprised we haven’t seen anything like this before though, it’s really rather fun. Also, how’s about that taste of the old Internet—when was the last time you heard somebody mention scrobbling? Gosh, we’re getting old.

We’ve featured some of [Guy’s] works before, too, like the amusing Mailblocks project. Video after the break.

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Building A Subwoofer Box Out Of Decking Material

September 12, 2024 by Lewin Day 8 Comments

When you go to build a subwoofer box, wood is the most common choice. When it came to his project, though, [Startup Chuck] decided to go a different route entirely. Rather than the usual plywood or MDF, he decided to try Trex decking instead. Why? He had some lying around, and he suspected it might just sound good.

If you’re unfamiliar with it, Trex decking is a composite material made of recycled materials like reclaimed wood and plastic film. The best part, though? Trex decking is twice as dense as MDF. That makes it good for speaker box use because it flexes less and thus absorbs less energy from the subwoofer. [Chuck] walks us through cutting out the parts for the box and the subsequent assembly. Ultimately, it’s not dissimilar from building a speaker box out of wood; the material is simply not that different—just denser.

[Chuck] also puts his new sub through some quick little tests, demonstrating that minimal vibration is passed through to the enclosure itself. He reports that the final build has a “nice, deep sound.” Meanwhile, if you don’t like working with your hands, you could always 3D-print your speaker enclosures instead.

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Supercon 2023: Aleksa Bjelogrlic Dives Into Circuits That Measure Circuits

September 11, 2024 by Lewin Day 10 Comments

Oscilloscopes are one of our favorite tools for electronics development. They make the hidden dances of electrons visually obvious to us, and give us a clear understanding of what’s actually going on in a circuit.

The question few of us ever ask is, how do they work? Most specifically—how do you design a circuit that’s intended to measure another circuit? Aleksa Bjelogrlic has pondered that very idea, and came down to explain it all to us at the 2023 Hackaday Supercon.

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