Taking “Movies” Of Light In Flight

December 25, 2024 by Elliot Williams 10 Comments

This one isn’t clickbait, but it is cheating. [Brian Haidet], the guy behind Alpha Phoenix, has managed to assemble movie footage of a laser beam crossing his garage, using a rig he put together for just a few hundred dollars. How, you ask? Well, for the long version, you’re going to want to watch the video, also embedded below. But we’ll give you the short version here.

Light travels about a foot in a nanosecond. What have you got that measures signals on a nanosecond scale pretty reliably? Of course, it’s your oscilloscope. The rest of [Brian]’s setup includes a laser that can pull off nanosecond pulses, a sensor with a nanosecond-ish rise time, and optics that collect the light over a very small field of view.

He then scans the effective “pinhole” across his garage, emitting a laser pulse and recording the brightness over time on the oscilloscope for each position. Repeating this many thousands of times and putting them all together relative to the beginning of each laser pulse results in a composite movie with the brightness at each location resolved accurately enough to watch the light beam fly. Or to watch different time-slices of thousands of beams fly, but as long as they’re all the same, there’s no real difference.

Of course, this isn’t simple. The laser driver needs to push many amps to get a fast enough rise time, and the only sensor that’s fast enough to not smear the signal is a photomultiplier tube. But persistence pays off, and the results are pretty incredible for something that you could actually do in your garage.

Photomultiplier tubes are pretty damn cool, and can not only detect very short light events, but also very weak ones, down to a single photon. Indeed, they’re cool enough that if you get yourself a few hundred thousand of them and put them in a dark place, you’re on your way to a neutrino detector. Continue reading “Taking “Movies” Of Light In Flight” →

A Twenty-Segment Display, Artistically

December 24, 2024 by Elliot Williams 21 Comments

We all know and love the humble seven-segment display, right? And if you want to make characters as well as numbers, you can do an okay job with sixteen segments off the shelf. But if you want something more art-deco, you’ll probably want to roll your own. Or at least, [Ben] did, and you can find his designs up on GitHub.

Taking inspiration from [Posy]’s epic investigation of segmented displays, [Ben] sat down with a sketchpad and created his own 20-segment font that displays numbers and letters with some strange, but frankly lovely, segment shapes. There is no center line, so letters like “T” and numbers like “1” are a little skewed, but we think it’s charming.

We’ve seen about a bazillion takes on the seven-segment idea over the years here. Most recently, we fell in love with this 21-segment beauty, but honestly the original eight(!) segment patent version is charming as well. Anyway, picking a favorite segmented display at Hackaday is like picking your favorite child, if you have a few hundred children. We love them all.

Continue reading “A Twenty-Segment Display, Artistically” →

The Mystery Of The Messed-Up Hammond X5

December 24, 2024 by Elliot Williams 4 Comments

[Filip] got his hands on a sweet old Hammond X5 organ, but it had one crucial problem: only half of the keys worked. Each and every C#, D, D#, E, F, and F# would not play, up and down the keyboard, although the other notes in between sounded just fine.

Those of you with an esoteric knowledge of older electric organs will be saying “it’s a busted top-octave generator chip”, and you’re right. One of the TOGs worked, and the other didn’t. [Filip] rolled his own top-octave generator with a Pico, in Python no less, and the old beauty roared to life once more.

But what is a top-octave generator, you may ask? For a brief period of time in the early 70s, there were organs that ran on square waves. Because a musical octave is a doubling or halving of frequency, you can create a pitch for every key on the organ if you simply create one octave’s worth of pitches, and divide them all down using something as simple as a binary counter IC. But nobody makes top-octave chips any more.

Back in 2018, [DC Darsen] wrote in asking us if we knew about any DIY top-octave designs, and we put out an Ask Hackaday to see if you all could make a top-octave generator out of a microcontroller. We got a super-optimized code hack in response, and that’s worth checking out in its own right, but we always had the nagging suspicion that a hardware solution was the best solution.

We love how [Filip]’s design leans heavily on the Pico’s programmable input/output hardware modules to get the job done with essentially zero CPU load, allowing him to write in Python and entirely bypassing the cycle-counting and assembly language trickery. The voltage shifters and the switchable jumpers to swap between different top-octave chip types are a nice touch as well. If you have an organ that needs a top-octave chip in 2024, this is the way we’d do it. (And it sounds fantastic.)

Continue reading “The Mystery Of The Messed-Up Hammond X5” →

Watch Any Video On Your Game Boy, Via Link Cable

December 23, 2024 by Elliot Williams 6 Comments

Game Boys have a link cable that lets two of them play together. You know, to battle with a friend’s Pokemon and stuff like that. But who says that it should be limited to transmitting only what Big N wants you to?

[Chromalock] wrote a custom GB program that takes in data over the link cable, and displays it on the screen as video, as fast as it can be sent. Add in a microcontroller, a level shifter, and software on the big computer side, and you can hook up your Game Boy Color as a normal video device and send it anything you want, from a webcam to any program that outputs video.

Well, almost. The biggest limitation is the data link cable, of course. On the older Game Boys, the link cable is apparently only good for 8 kHz, while the Color models can pull a not-quite-blistering 512 kHz. Still, that’s enough for 60 fps in a low-res black and white mode, or a slow, screen-tearing high-res color experience. You pick your poison.

There are gotchas that have to do with the way the GB displays palettes that get left as “to-do” on the software side. There is room for improvement in hardware too. (GB Link looks like SPI to us, and we’d bet you can push the speeds even higher with clever GB-side code.) In short, this is an awesome demo that just invites further hacking.

If you want to know more about the Game Boy to get started, and maybe even if you don’t, you absolutely must watch The Ultimate Game Boy Talk. Trust us on this one.

Continue reading “Watch Any Video On Your Game Boy, Via Link Cable” →

Hacker Tools, Hacked Tools

December 14, 2024 by Elliot Williams 3 Comments

We just love a good DIY tool project, and more so when it’s something that we can actually use cobbled together from stuff in our closet, or hacked out of cheap “toys”. This week we saw both a superb Pi Pico-based logic analyzer and yet another software frontend for the RTL-SDR dongle, and they both had us thinking of how good we have it.

If you don’t already have a logic analyzer, or if you have one of those super-cheap 8-channel jobbies, it might be worth your while to check out the Pico firmware simply because it gets you 24 channels, which is more than you’ll ever need™. At the low price of $4, maybe a little more if you need to add level shifters to the circuit to allow for 5 V inputs, you could do a lot worse for less than the price of a fancy sweet coffee beverage.

And the RTL dongle; don’t get us started on this marvel of radio hacking. If you vaguely have interest in RF, it’s the most amazing bargain, and ever-improving software just keeps adding functionality. The post above adds HTML5 support for the RTL-SDR, allowing you to drive it with code you host on a web page, which makes the entire experience not only cheap, but painless. Talk about a gateway drug! If you don’t have an RTL-SDR, just go out and buy one. Trust me.

What both of these hacker tools have in common, of course, is good support by a bunch of free and open software that makes them do what they do. This software enables a very simple piece of hardware to carry out what used to be high-end lab equipment functions, for almost nothing. This has an amazing democratizing effect, and paves the way for the next generation of projects and hackers. I can’t think of a better way to spend $20.

2025 Hackaday Europe CFP: We Want You!

December 10, 2024 by Elliot Williams 13 Comments

Hackaday’s Supercon is still warm in our hearts, and the snow is just now starting to fall, but we’re already looking forward to Spring. Or at least to Hackaday Europe, which will be taking place March 15th and 16th in Berlin, Germany.

Tickets aren’t on sale yet, but we know a way that you can get in for free.

Call for Participation

What makes Hackaday Europe special? Well, it’s you! We’re excited to announce that we’re opening up our call for talks right now, and we can’t wait to hear what you have to say. Speakers of course get in free, but the real reason that you want to present is whom you’re presenting to.

The Hackaday audience is interested, inquisitive, and friendly. If you have a tale of hardware, firmware, or software derring-do that would only really go over with a Hackaday crowd, this is your chance. We have slots open for shorter 20-minute talks as well as longer 40-minute ones, so whether you’ve got a quick hack or you want to take a deep dive, we’ve got you covered. We especially love to hear from new voices, so if you’ve never given a talk about your projects before, we’d really encourage you to apply!

Here is last year’s lineup, if you’re wondering what goes on, and if your talk would fit in.

Continue reading “2025 Hackaday Europe CFP: We Want You!” →

Tis The Season

December 7, 2024 by Elliot Williams 16 Comments

’Tis the season for soldering! At least at my house. My son and I made some fairly LED-laden gifts for the immediate relatives last year, and he’s got the blinky bug. We were brainstorming what we could make this year, and his response was “I don’t care, but it needs to have lots of LEDs”.

It’s also the season for reverse engineering, apparently, because we’re using a string of WS2812-alike “fairy lights”. These are actually really neat, they look good and are relatively cheap. It’s a string of RGB LEDs with drivers, each dipped in epoxy, and run on a common three-enameled-wire bus. Unlike WS2812s, which pass the data on to the next unit in the line and then display them with a latching pulse at the end of a sequence, these LED drivers seem to count how many RGB packets have been sent down the wire, and only respond to their own number.

This means that if you cut up a string of 200 LEDs, it behaves like a string of 200 WS2812s. But if you cut say 10 LEDs off the string, where you cut them matters. If you cut it off the front of the string, you only have to send 10 color packets. If you cut them off the other end, you need to send 290 dummy packets before they even start listening. Bizarre, but ’tis the season for bizarre hacks.

And finally, ’tis the season for first steps into “software architecture”. Which is to say that my son is appreciating functions for the first time in his life. Controlling one LED is easy, but making a light show is about two more abstraction layers on top of that. We’ve been having fun making them dim, twinkle, and chase so far. We only have two more weekends, though, and we don’t have a final light show figured out yet, but after all, ’tis the season for last minute present hacking.