Two sides of a business-card shaped device are shown. On the left, it’s clear that the device is about half a centimeter thick, with a large scroll wheel visible in the center. The device cover is 3D-printed in black plastic, and has cutouts to mark where three buttons ar. On the right, the underside of the device is visible. It is a black PCB, with white text giving contact information.

Building A Macro Pad Into A Business Card

August 31, 2025 by Aaron Beckendorf 10 Comments

A business card is a convenient way to share your contact information, but it’s unfortunately prone to being thrown away or forgotten. PCB business cards try to get around this problem, but while impressive, most won’t keep the recipient engaged for a very long time. [Cole Olsen]’s macro pad business card, on the other hand, might actually get regular use.

The card has three buttons and a rotary encoder as controls, with an RGB LED to indicate the card’s current mode. It can perform three sets of functions: general productivity, serving as a presentation remote, and controlling music. The scroll wheel is the main control, and can switch through windows, desktops, and tabs, page through slides, and control music volume.

The card itself is made out of a PCB, the exposed side of which contains [Cole]’s contact information, and the other side of which is covered by a 3D-printed case. As thick as it is, this might be stretching the definition of “card” a bit, but as a mechanical engineer, [Cole] did want to demonstrate some mechanical design. A nice!nano wireless keyboard development board running ZMK firmware reads the sensors and sends commands. Conveniently for a presentation remote, the card is powered by a rechargeable battery and can work wirelessly (as a side benefit, if a recipient were minded to get rid of this card, the lithium-polymer battery would probably substantially delay disposal).

[Cole] writes that he was inspired by many of the other impressive business cards we’ve covered. Some of the macro pads we’ve seen have been marvels of miniaturization in their own right.

Who Is Your Audience?

August 23, 2025 by Elliot Williams 29 Comments

Here at Hackaday HQ, we all have opinions about the way we like to do things. And no surprise, this extends to the way we like to lay out circuits in schematics. So when we were discussing our own takes on this piece on suggested schematic standards, it was maybe more surprising how much we did agree on than how much we had different preferred styles. But of course, it was the points where we disagreed that provoked the most interesting discussion, and that’s when I had a revelation.

Besides torturing electronics, we all also write for you all, and one thing we always have in mind is who we’re writing for. The Hackaday audience, not to blow you up, is pretty knowledgeable and basically “full-stack” in terms of the hardware/software spectrum. This isn’t to say that everyone is a specialist in everything, though, and we also have certain archetypes in mind: the software type who is just starting out with hardware, the hardware type who isn’t as savvy about software, etc. So, back to schematic layout: Who is your audience? It matters.

For instance, do you organize the pinout for an IC by pin number or by pin function, grouping the power pins and the ADC pins and so on? If your audience is trying to figure out the circuit logic, you should probably go functional. But if you are trying to debug a circuit, you’re often looking at the circuit diagram to figure out what a given pin does, and the pin-number layout is more appropriate.

Do you lay out the logical flow of the circuit in the schematic, or do you try to mimic the PCB layout? Again, it could depend on how your audience will be using it. If they have access to your CAD tool, and can hop back and forth seamlessly from schematic to PCB, the logical flow layout is the win. However, if they are an audience of beginners, or stuck with a PDF of the schematic, or trying to debug a non-working board, perhaps the physical layout is the right approach.

Al Williams, who has experience with projects of a much larger scale than most of us self-taught hackers, doesn’t even think that a schematic makes sense. He thinks that it’s much easier to read and write the design in a hardware description language like VHDL. Of course, that’s certainly true for IC designs, and probably also for boards of a certain complexity. But this is only true when your audience is also familiar with the HDL in question. Otherwise, you’re writing in Finnish for an audience of Spaniards.

Before this conversation, I was thinking of schematic layout as Tom Nardi described it on the podcast – a step along the way to get to the fun parts of PCB layout and then to getting the boards in hand. But at least in our open-source hardware world, it’s also a piece of the documentation, and a document that has an audience of peers who it pays to keep in mind just as much as when I’m sitting down and writing this very newsletter. In some ways, it’s the same thing.

(And yeah, I know the featured image doesn’t exactly fit the topic, but I love it anyway.)

How To Stop Zeus From Toasting Your Pi

August 22, 2025 by Heidi Ulrich 18 Comments

If you’ve ever lost gear to lightning or power spikes, you know what a pain they are. Out in rural Arkansas, where [vinthewrench] lives, the grid is more chaos than comfort – especially when storms hit. So, he dug into the problem after watching a cheap AC-DC module quite literally melt down. The full story, as always, begins with the power company’s helpful reclosers: lightning-induced surges, and grid switching transients. The result though: toasted boards, shorted transformers, and one very dead Raspberry Pi. [vinthewrench] wrote it all up – with decent warnings ahead. Take heed and don’t venture into things that could put your life in danger.

Back to the story. Standard surge suppressors? Forget it. Metal-oxide varistor (MOV)-based strips are fine for office laptops, but rural storms laugh at their 600 J limits. While effective and commonly used, MOVs are “self-sacrificing” and degrade over time with each surge event.

[vinthewrench] wanted something sturdier. Enter ZeusFilter 1.0 – a line-voltage filter stitched together from real parts: a slow-blow fuse, inrush-limiting thermistor, three-electrode gas discharge tube for lightning-class hits, beefy MOVs for mid-sized spikes, common-mode choke to kill EMI chatter, and safety caps to bleed off what’s left. Grounding done right, of course. The whole thing lives on a single-layer PCB, destined to sit upstream of a hardened PSU.

As one of his readers pointed out, though, spikes don’t always stop at the input. Sudden cut-offs on the primary can still throw nasty pulses into the secondary, especially with bargain-bin transformers and ‘mystery’ regulators. The reader reminded that counterfeit 7805s are infamous for failing short, dumping raw input into a supposedly safe 5 V rail. [vinthewrench] acknowledged this too, recalling how collapsing fields don’t just vanish politely – Lenz makes sure they kick back hard. And yes, when cheap silicon fails, it fails ugly: straight smoke-release mode.

In conclusion, we’re not particularly asking you to try this at home if you lack the proper knowledge. But if you have a high-voltage addiction, this home research is a good start to expand your knowledge of what is, in theory, possible.

A brown plastic circuit board is visible in the middle of the picture, containing an integrated circuit, a resistor, a diode, two capacitors, and some jumper wires going away to the sides.

A Solderless, Soluble Circuit Board

August 19, 2025 by Aaron Beckendorf 25 Comments

Anyone who’s spent significant amounts of time salvaging old electronics has probably wished there were a way to take apart a circuit board without desoldering it. [Zeyu Yan] et al seem to have had the same thought, and designed circuit boards that can be dissolved and recycled when they become obsolete. Read the details in the research paper. (PDF)

The researchers printed the circuit boards out of water-soluble PVA, with hollow channels in place of interconnects. After printing the boards, they injected a eutectic gallium-indium liquid metal alloy into these channels, populated the boards with components, making sure that their leads were in contact with the liquid alloy, and finally closed off the channels with PVA glue, which also held the components in place. When the board is ready to recycle, they simply dissolve the board and glue in water. The electric components tend to separate easily from the liquid alloy, and both can be recovered and reused. Even the PVA can be reused: the researchers evaporated the solution left after dissolving a board, broke up the remaining PVA, and extruded it as new filament.
Continue reading “A Solderless, Soluble Circuit Board” →

PCB Business Card Plays Pong, Attracts Employer

August 13, 2025 by Tyler August 11 Comments

Facing the horrifying realization that he’s going to graduate soon, EE student [Colin Jackson] AKA [Electronics Guy] needed a business card. Not just any business card: a PCB business card. Not just any PCB business card: a PCB business card that can play pong.

[Colin] was heavily inspired by the card [Ben Eater] was handing out at OpenSauce last year, and openly admits to copying the button holder from it. We can’t blame him: the routed-out fingers to hold a lithium button cell were a great idea. The original idea, a 3D persistence-of-vision display, was a little too ambitious to fit on a business card, so [Colin] repurposed the 64 LED matrix and STM32 processor to play Pong. Aside from the LEDs and the microprocessor, it looks like the board has a shift register to handle all those outputs and a pair of surface-mount buttons.

Of course you can’t get two players on a business card, so the microprocessor is serving as the opponent. With only 64 LEDs, there’s no room for score-keeping — but apparently even the first, nonworking prototype was good enough to get [Colin] a job, so not only can we not complain, we offer our congratulations.

The video is a bit short on detail, but [Colin] promises a PCB-business card tutorial at a later date. If you can’t wait for that, or just want to see other hackers take on the same idea, take a gander at some of the entries to last year’s Business Card Challenge. Continue reading “PCB Business Card Plays Pong, Attracts Employer” →

Creating A New Keyboard Flex For An Old Calculator

August 12, 2025 by Lewin Day 19 Comments

[Menadue] had a vintage Compucorp 326 calculator with an aging problem. Specifically, the flex cable that connects the button pad had turned corroded over time. However, thanks to the modern PCB industrial complex, replacing the obscure part was relatively straightforward!

The basic idea was simple enough: measure the original flex cable, and recreate it with the flat-flex PCB options available at many modern PCB houses that cater to small orders and hobbyists. [Menadue] had some headaches, having slightly misjudged the pitch of the individual edge-connector contacts. However, he figured that if lined up just right, it was close enough to still work. With the new flex installed, the calculator sprung into life…only several keys weren’t working. Making a new version with the correct pitch made all the difference, however, and the calculator was restored to full functionality.

It goes to show that as long as your design skills are up to scratch, you can replace damaged flex-cables in old hardware with brand new replacements. There’s a ton of other cool stuff you can do with flex PCBs, too.

Continue reading “Creating A New Keyboard Flex For An Old Calculator” →

Design Review: LattePanda Mu NAS Carrier

August 12, 2025 by Arya Voronova 17 Comments

It is a good day for design review! Today’s board is the MuBook, a Lattepanda Mu SoM (System-on-Module) carrier from [LtBrain], optimized for a NAS with 4 SATA and 2 NVMe ports. It is cheap to manufacture and put together, the changes are non-extensive but do make the board easier to assemble, and, it results in a decent footprint x86 NAS board you can even order assembled at somewhere like JLCPCB.

This board is based on the Lite Carrier KiCad project that the LattePanda team open-sourced to promote their Mu boards. I enjoy seeing people start their project from a known-working open-source design – they can save themselves lots of work, avoid reinventing the wheel and whole categories of mistakes, and they can learn a bunch of design techniques/tips through osmosis, too. This is a large part of why I argue everyone should open-source their projects to the highest extent possible, and why I try my best to open-source all the PCBs I design.

Let’s get into it! The board’s on GitHub as linked, already containing the latest changes.

Git’ting Better

I found the very first review item when downloading the repo onto my computer. It took a surprising amount of time, which led me to believe the repo contains a fair bit of binary files – something quite counterproductive to keep in Git. My first guess was that the repo had no .gitignore for KiCad, and indeed – it had the backups/ directory with a heap of hefty .zips, as well as a fair bit of stuff like gerbers and footprint/symbol cache files. I checked in with [LtBrain] that these won’t be an issue to delete, and then added a .gitignore from the Blepis project.

Continue reading “Design Review: LattePanda Mu NAS Carrier” →