A tuna fish with several probes sticking out of it.

So You Can Tuna Fish

July 19, 2024 by Kristina Panos 10 Comments

You know what they say. But it’s 2024, after all. Shouldn’t you be able to tune a fish by now? As [ChromaLock] shows us in the video below, it’s absolutely possible, and has been all along.

Of course, you can’t possibly put a rainbow trout (or any other fish) under tension until it produces audible tones. So, how does it work? [ChromaLock] turned to the skin, which functions electrically much like ours does with different resistance values in different areas.

From there, it was a matter of hunting around for spots that produced different notes that sounded good, and marking them for later so it can be played like a potentiometer. But there were problems with this setup, mostly screeching between notes from stray voltages in the environment.

After a brief detour using a PS/2 keyboard with spray-painted keycaps, [ChromaLock] said to hell with it and unearthed a regular MIDI keyboard. Armed with a 3D printed jig to hold the probes, [ChromaLock] tested everything with a cucumber, and then out came the trout for its musical debut. Be sure to check it out after the break.

What else can you do with canned tuna and other fish? Cook up some pyrolized bread, and you’ve got yourself a foundry and crucible.

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Simple Version Of Pong Played On A Row Of LEDs

July 15, 2024 by Tom Nardi 5 Comments

As far as video games go, Pong is already about as simple as it gets. But if even two dimensions is a bit more than you’re looking to tackle, [mircemk] shows how you can distill the core gameplay of this iconic title to its absolute minimum using an Arduino and a row of LEDs.

While [mircemk] brings their usual design aesthetic and flash to the project, this one could truly be done as a parts bin build. All you really need is a microcontroller with enough I/O pins (here, an Arduino Nano is used), a couple of buttons, and the aforementioned LEDs. A 16×2 LCD and a buzzer have been added to improve on the user interface a bit, but even that isn’t strictly required.

To play, each user holds their button and gets ready to hit it as soon as the LED closest to them lights up. Again, [mircemk] spruces this build up by offering both integrated buttons on the front panel of the game, as well as a pair of external “controllers” so you don’t have to crowd around the main unit. In this incarnation the score is shown on the LCD, but swapping that out for a pair of seven-segment LEDs could give the whole thing a bit more of a retro flair.

This isn’t the first time [mircemk] has tackled 1D Pong — if you can spring for addressable LEDs, you can pull the whole thing off with significantly less wiring.

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Undo Arduino Encryption With An Oscilloscope

July 14, 2024 by Elliot Williams 16 Comments

Cryptography ain’t easy. Seemingly small details like how many times a computationally intensive loop runs can give the game away. [Lord Feistel] gives us a demo of how this could work with nothing more than poorly designed code, a resistor, and an oscilloscope.

The hardware side is, as mentioned, really simple. Put a resistor inline with the Arduino and monitor the voltage drop across the resistor with the scope. When the chip is working hard, it consumes more current, and code sections that take longer will show up as longer dips.

On the software end, it’s only a little more complicated. The RSA encryption scheme involves a lot of exponentiation and modulo-taking. Here, [Lord Feistel] is targeting a naive way of computing the exponents quickly, and demonstrates how you can read the exponent straight out the chip’s power demand.

Implementing this attack against a real-world RSA algorithm, in the context of the Arduino doing other stuff, will be harder. And we don’t know if the algorithm implemented in “standard” Arduino libraries is smarter than this one. (If you know, let us know in the comments.) But still, this is a cool example of just how simple and straightforward it can be to eavesdrop on bad code.

If you only need to bypass encryption instead of breaking it, check out [Lord Feistel]’s other tutorial on power glitching that we featured previously. If you haven’t played around with the hardware side of security, it gets deep pretty quickly, but you can at least dip your toes in the shallow end with what you’ve got in your closet.

A DIY Proximity Sensor, Using Just Scrap Parts And Software

July 1, 2024 by Donald Papp 7 Comments

[mircemk] shows how to create a simple non-contact proximity sensor using little more than an Arduino Nano board, and a convenient software library intended to measure the value of capacitors.

The prototype has a threshold set via potentiometer for convenience.

The basic idea is that it’s possible to measure a capacitor’s capacitance using two microcontroller pins and the right software, so by using a few materials to create an open-style capacitor, one can monitor it for changes and detect when anything approaches enough to alter its values past a given threshold, creating a proximity sensor.

The sensor shown here is essentially two plates mounted side-by-side, attached to an Arduino Nano using the Capacitor library which uses just two pins, one digital and one analog.

As configured, [mircemk]’s sensor measures roughly thirty picofarads, and that value decreases when approached by something with a dielectric constant that is different enough from the air surrounding the sensor. The sensor ignores wood and plastic, but an approaching hand is easily detected. The sensor also detects liquid water with similar ease, either in the form of pooled liquid, or filled bottles.

We’ve also seen a spring elegantly used as a hidden touch sensor that works through an enclosure’s wall by using similar principles, so the next time you need a proximity or touch-sensitive sensor in a project, reaching for the junk box might get you where you need to go. Watch [mircemk]’s sensor in action in the video, just below the page break.

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Hosting Your Own PixMob Party Made Easy

June 28, 2024 by Tom Nardi 10 Comments

Over the last few years, it’s been increasingly common for concertgoers to be handed a light-up bracelet from PixMob that synchronizes with the others in the crowd to turn the entire audience into a music visualizer. They’re a clever way of enhancing the concert experience, but unfortunately, they don’t do anything once you leave the show. Or at least, that used to be the case.

We’ve seen efforts to reverse engineer the IR (and occasionally radio) signals that drive these PixMob devices, but since we checked in last it seems like things have gotten a lot easier for the home gamer. [David Pride] has recently posted a brief write-up that shows how quickly and easily it is to get these devices fired up using nothing more exotic than an Arduino, an IR LED, and an audio sensor module.

With the audio sensor module connected to the Arduino’s digital input and the IR LED wired to digital out, all you need to do is flash firmware to the board and start playing some beats. The source code [David] has provided is a a remixed version of what’s previously been published by [Carlos Ganoza], which, in this case, has been tweaked to make the lighting patterns less random.

Presumably, this is to make the devices behave more like they do during an actual concert, but since nobody at Hackaday is cool enough to have seen a live musical performance in the last decade, we’re not really sure. All we can say is that the effect looks pretty sweet in the demo video.

Back in 2019, we saw a teardown of an early PixMob device, and by 2022, the efforts to reverse engineer their IR control protocol were well underway. We’re glad to see things have progressed to the point that you can piece together a transmitter from what’s in the parts bin, as it means at least some of these devices will have a lifespan longer than a single concert.

Enjoy Totality Every Day With This Personal Eclipse Generator

June 27, 2024 by Dan Maloney 29 Comments

There have been a couple of high-profile solar eclipses lately, but like us, you probably missed the news of the one that passed over Munich in 2019. And every day since then, in fact, unless you were sitting in a particular spot: the couch of one [Bernd Kraus], who has his very own personal eclipse generator.

We’ll attempt to explain. Living in an apartment with a gorgeous western view of Munich is not without its cons, chief among which is the unobstructed exposure to the setting sun. Where most people would opt for a window treatment of some sort to mitigate this, [Bernd] felt that blotting out the entire view was a heavy-handed solution to the problem. His solution is a window-mounted X-Y gantry that dangles a cutout of the moon in just the right place to blot out the sun. An Arduino uses the time and date to calculate the position of the sun as it traverses the expansive window and moves the stepper motors to keep the moon casting its shadow in just the right place: on his face as he sits in his favorite spot on the couch.

There are a couple of time-lapse sequences in the video below, as well as a few shots of the hardware. We know this isn’t an actual coronagraph, but the effect is pretty cool, and does resemble an eclipse, at least in spirit. And it goes without saying that we applaud the unnecessary complexity embodied by this solution.

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A PCB business card that plays tic-tac-toe with red and blue LEDs.

2024 Business Card Challenge: Go Tic-Tac-Toe-to-Toe With Them

June 24, 2024 by Kristina Panos 4 Comments

There is perhaps no more important time to have a business card than when you’re in college, especially near the end when you’re applying for internships and such. And it’s vital that you stand out from the crowd somehow. To that end, Electrical & Computer Engineer [Ryan Chan] designed a tidy card that plays tic-tac-toe.

Instead of X and O, the players are indicated by blue and red LEDs. Rather than having a button at every position, there is one big control button that gets pressed repeatedly until your LED is in the desired position, and then you press and hold to set it and switch control to the other player. In addition to two-player mode, the recipient of your card can also play alone against the ATMega.

The brains of this operation is an ATMega328P-AU with the Arduino UNO bootloader for ease of programming. Schematic and code are available if you want to make your own, but we suggest implementing some type of changes to make it your own. Speaking of, [Ryan] has several next steps in mind, including charlieplexing the LEDs, using either USB-C or a coin cell for power, upgrading the AI, and replacing the control button with a capacitive pad or two. Be sure to check it out in action in the two videos after the break.

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