Congratulations To The 2024 Business Card Challenge Winners!

When you ask a Hackaday crowd to design a business card, you should expect to be surprised by what you get. But still, we were surprised by the breadth of entries! Our judges wracked their brains to pick their top ten, and then we compared notes, and three projects rose to the top, but honestly the top ten could have all won. It was a tight field. But only three of the entries get to take home the $150 DigiKey gift certificates, so without further ado…

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A business card-sized synthesizer with capacitive touch pads.

2024 Business Card Challenge: The Gift Of Music

Has anyone ever told you that you just can’t carry a tune? If you were to be the lucky recipient of one of [Ayu]’s synthesizer business cards, well, then it really couldn’t be helped.

This tiny, go-anywhere instrument has quite a lot going for it. It’s easy for anyone to pick up and play something, but versatile enough that a more experienced musician can add complexity. While we do tend to see twelve keys in a small form-factor like this, the Canta-Cart uses them a bit differently. Only ten are tied to notes, and the other two are for transposition.

[Ayu] was able to keep the BOM cost way down by using the PY32, which is an ARM Cortex-M microcontroller made by Puya that costs as little as 10¢ each. In fact, the whole BOM clocks in around 60¢ total even with the audio DAC and amplifier ICs, which really makes these ideal to actually give away to people. Check it out in action after the break, or try it in the browser!

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A bunch of unpopulated PCB business cards with rad dead rat artwork.

2024 Business Card Challenge: A Very Annoying Business Card, Indeed

Usually the business card itself is the reminder to get in contact with whoever gave it to you. But this is Hackaday, after all. This solar-powered card reminds the recipient to send [Dead Rat Productions] an email by beeping about every two hours, although the gist of that email may simply be begging them to make it stop, provided they didn’t just toss the thing in the garbage.

The full-on, working version of the card is not intended for everyone — mostly serious-looking A-list types that ooze wealth. Most of [Dead Rat Productions]’ pub mates will get an unpopulated version, which could be a fun afternoon for the right kind of recipient, of course.

That person would need a Seeed Studio Xiao SAMD21, a solar panel, plus some other components, like an energy-harvesting chip to keep the battery topped up. Of note, there is a coin cell holder that requires prying with a screwdriver to get the battery out, so there’s really no escaping the beeping without some work on their part. We rather like the artwork on this one, especially the fact that the coin cell sits inside the rat’s stomach. That’s a nice touch.

A 3D-printed magnetic fidget business card with ID storage.

2024 Business Card Challenge: Magnetic Fidget Card

If you want someone to keep your business card around, you should probably make it really cool-looking, or have it do something useful. It’s kind of the whole point of the 2024 Business Card Challenge. And while we’d normally expect electronics of some persuasion to be involved, we must admit that this magnetic fidget card definitely does something, at least when manipulated. And even when it’s just sitting there, the card has a storage slot for IDs, or whatever you want.

Have you ever played with a magnetic fidget? They are quite satisfying, and making one yourself is likely to be even cheaper than making one of the spinning variety. This one uses a whopping 16 neodymium magnets, which means that it’s probably quite aurally satisfying as well as fun to handle.

And of course, since it’s 3D-printed, you can put whatever you want on the faces and update them easily if something changes. Bonus points to [Bhuvan Bagwe] for designing some for the Hackaday crew!

A battery-testing business card.

2024 Business Card Challenge: A Battery Tester With Blinkenlights

Readers of a certain vintage will no doubt remember that for a brief time, some alkaline batteries came with a built-in battery tester. Basically, you just pushed really hard with your fingernails on the two ends of the strip, and it either lit up the little strip (or didn’t if it was dead), or made the word ‘good’ appear if energized.

But those days are long gone. What you need now is to either grab the voltmeter, stick out your tongue, or build yourself a battery-testing business card. Even the normies will enjoy this one, mostly because LEDs. Forty-seven of them to be exact, which will come to life and demonstrate that [Greg] is capable of making working electronic gadgets. No way does this card end up at the bottom of a desk drawer.

As far as grasping the batteries goes, [Greg] had several ideas, but ultimately landed on pogo pins, which we think is a fabulous solution. Be sure to check out the neat interactive BOM, somewhere in the middle of which is the CH32v003 RISC-V microcontroller. In the video after the break, you can see [Greg] using a Flipper Zero to program it.

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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

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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A solar-powered decibel meter the size of a business card.

2024 Business Card Challenge: NoiseCard Judges The Sound Around You

Let’s face it: even with the rise of the electric car, the world is a noisy place. And it seems like it has only gotten worse in recent years. But how can we easily quantify the noise around us and know whether it is considered an unhealthy decibel level?

That is where the NoiseCard comes in. This solar-powered solution can go anywhere from the regrettable open office plan to the busy street, thanks to a couple of 330 µF capacitors. It’s based on the low-power STM32G031J6 and uses a MEMS microphone to pick up sound from the back of the card, which the code is optimized for. Meanwhile, the LEDs on the front indicate the ambient noise level, ranging from a quiet 40 dB and under to an ear-splitting 105 dB or greater.

When it comes to building something the size of a business card, every component is under scrutiny for size and usefulness. So even the LEDs are optimized for brightness and low power consumption. Be sure to check it out in action after the break in various environments.

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