Here’s a clever hack. Simple, elegant, and eminently cost-effective: using an SMD capacitor to hold your flash media in place!

This is a hack that can pretty much be summed up with just the image at the top of the page — a carefully placed SMD capacitor soldered to a routed tab makes for an extremely cost effective locking mechanism for the nearby SD card slot. There’s just enough flexibility to easily move the capacitor when its time to insert or eject your media.

It’s worth noting that the capacitor in this example doesn’t even appear to be electrically connected to anything. But there’s also no reason you couldn’t position one of the capacitors in your existing bill of materials (BOM). This form of mechanical support will be much cheaper than special purpose clips or mounts. Not a big deal for low-volume projects, but if you’re going high-volume this is definitely something to keep in mind.

If you’re just getting started with SMD capacitors then one of the first things to learn is how to solder them. Also, if you’re hoping to salvage them then try to look for newer equipment which is more likely to have SMD components than through-hole. If you’re planning to use your capacitors for… “capacitance” (how quaint), you can start by learning the basics. And if you want to know everything you can learn about the history of capacitors, too.

Thanks to [JohnU] for writing in to let us know about this one. Have your own natty hacks? Let us know on the tipsline!

Today in old school nostalgia our tipster [Clint Jay] wrote in to let us know about this rotary dial.

If you’re a young whippersnapper you might never have seen a rotary dial. These things were commonly used on telephones back in the day, and they were notoriously slow to use. The way they work is that they generate a number of pulses corresponding to the number you want to dial in. One pulse for 1, two pulses for 2, and so on, up to nine pulses for 9, then ten pulses for 0.

We see circuits like this here at Hackaday from time to time. In fact, commonly we see them implemented as USB keyboards, such as in Rotary Dial Becomes USB Keyboard and Rotary Dialer Becomes Numeric Keypad.

One thing that makes this particular project different from the ones we’ve seen before is that it doesn’t require a microcontroller. That said, our hacker [Mousa] shows us how to interface this dial with an Arduino, along with sample code, if that’s something you’d like to do. The schematic for the project shows how to connect the rotary dial (salvaged from an old telephone) to both a 7-segment display and a collection of ten LEDs.

The project write-up includes links to the PCB design files. The guts of the project are a 4017 decade counter and a 4026 7-segment display adapter. Good, honest, old school digital logic.

For those of us who’ve spent far too long hammering rubber keys into submission, a glorious solution has arrived. [Lee Smith] designed the ZX Mechtrum Deluxe, the ultimate keyboard upgrade for your beloved ZX Spectrum 48k. Thanks to [morefunmakingit], you can see this build-it-yourself mechanical mod below. It finally brings a proper spacebar and Spectrum-themed Wraith keycaps into your retro life.

The Metrum Deluxe is a full PCB redesign: no reused matrices or clunky membrane adapters here. [Lee Smith] got fed up with people (read: the community, plus one very persistent YouTuber) asking for a better typing experience, so he delivered. Wraith keycaps from AliExpress echo the original token commands and BASIC vibe, without going full collector-crazy. Best of all: the files are open. You can download the case on Printables and order the PCB through JLCPCB. Cherry on top (pun intended): you’ll finally have a spacebar your thumbs can be proud of.

So whether you’re into Frankenstein rigs or just want your Spectrum to stop feeling like an air mattress, check this video out. Build files and link to the keycaps can be found on Youtube, below the video.

Tip: if you foster a secret love for keyboards, don’t miss the Keebin’ with Kristina’s series on all sorts of keyboards.

[Kalesh Sasidharan] from Sciotronics wrote in to tell us about their project, Stamp: a modular set of template breakout boards designed to make prototyping with SMD components faster, easier, and more affordable. No breadboards, custom PCBs, or tangled jumper wires required. The project has blasted past its Kickstarter goal, and is on track to start shipping in September.

Stamp was created out of frustration with the traditional SMD prototyping workflow. Breadboards don’t support SMD parts directly, and using adapters quickly gets messy, especially when you need to iterate or modify a design. Ordering PCBs for every small revision just adds delay, and cost.

Stamp solves this by offering reusable template boards with commonly used SMD footprints. You place the main component on the front and the supporting components on the back. Many complete circuits, such as buck converters, sensor blocks, microcontrollers, and so on, can fit on a single 17.8 × 17.8 mm board.

Most Stamps feature custom castellated holes, designed for side-by-side or right-angle edge connections, enabling a modular, reconfigurable approach to circuit building. The plan is to make the designs fully open source, so that others can build or adapt them. Although many PCB manufacturers might not have the facilities to make the special castellated edges which are available on some Stamps.

Dave Jones from the EEVblog covered the Stamp on one of his recent Mailbag videos, which you can check out below. This isn’t the first time we’ve seen somebody promise to reinvent the breadboard, but we do appreciate the simplicity of this approach.

If you’re into retro CPUs and don’t shy away from wiring old-school voltages, [Mark]’s latest Intel 8080 build will surely spark your enthusiasm. [Mark] has built a full system board for the venerable 8080A-1, pushing it to run at a slick 3.125 MHz. Remarkable is that he’s done so using a modern Microchip FPGA, without vendor lock-in or proprietary flashing tools. Every step is open source.

Getting this vintage setup to work required more than logical tinkering. Mark’s board supplies the ±5 V and +12 V rails the 8080 demands, plus clock and memory interfacing via the M2GL005-TQG144I FPGA. The design is lean: two-layer PCB, basic level-shifters, and a CM32 micro as USB-to-UART fallback. Not everything went smoothly: incorrect footprints, misrouted gate drivers, thermal runaway in the clock section; but he managed to tackle it.

What sets this project apart is the resurrection of a nearly 50-year-old CPU. It’s also, how thoroughly thought-out the modern bridge is—from bitstream loading via OpenOCD to clever debugging of crystal oscillator drift using a scope. [Mark]’s love of the architecture and attention to low-level detail makes this more than a show-off build.

If you’ve ever squinted at a DE10-Nano wondering where the fun part begins, you’re not alone. This review of the Mr. MultiSystem 2 by [Lee] lifts the veil on a surprisingly noob-friendly FPGA console that finally gets the MiSTer experience out of the tinker cave and into the living room. Developed by Heber, the same UK wizards behind the original MultiSystem, this follow-up console dares to blend flexibility with simplicity. No stack required.

It comes in two varieties, to be precise: with, or without analog ports. The analog edition features a 10-layer PCB with both HDMI and native RGB out, Meanwell PSU support, internal USB headers, and even space for an OLED or NFC reader. The latter can be used to “load” physical cards cartridge-style, which is just ridiculously charming. Even the 3D-printed enclosure is open-source and customisable – drill it, print it, or just colour it neon green. And for once, you don’t need to be a soldering wizard to use the thing. The FPGA is integrated in the mainboard. No RAM modules, no USB hub spaghetti. Just add some ROMs (legally, of course), and you’re off.

Despite its plug-and-play aspirations, there are some quirks – for example, the usual display inconsistencies and that eternal jungle of controller mappings. But hey, if that’s the price for versatility, it’s one you’d gladly pay. And if you ever get stuck, the MiSTer crowd will eat your question and spit out 12 solutions. It remains 100% compatible with the MiSTer software, but allows some additional future features, should developers wish to support them.

Want to learn more? This could be your entrance to the MiSTer scene without having to first earn a master’s in embedded systems. Will this become an alternative to the Taki Udon announced Playstation inspired all-in-one FPGA console? Check the video here and let us know in the comments.

We all appreciate clear easy-to-read reference materials. In that pursuit [Andreas] over at Splitbrain sent in his latest project, Pinoutleaf. This useful web app simplifies the creation of clean, professional board pinout reference images.

The app uses YAML or JSON configuration files to define the board, including photos for the front and back, the number and spacing of pins, and their names and attributes.For example, you can designate pin 3 as GPIO3 or A3, and the app will color-code these layers accordingly. The tool is designed to align with the standard 0.1″ pin spacing commonly used in breadboards. One clever feature is the automatic mirroring of labels for the rear photo, a lifesaver when you need to reverse-mount a board. Once your board is configured, Pinoutleaf generates an SVG image that you can download or print to slide over or under the pin headers, keeping your reference key easily accessible.

Visit the GitHub page to explore the tool’s features, including its Command-Line Interface for batch-generating pinouts for multiple boards. Creating clear documentation is challenging, so we love seeing projects like Pinoutleaf that make it easier to do it well.

Most of us learned to design circuits with schematics. But if you get to a certain level of complexity, schematics are a pain. Modern designers — especially for digital circuits — prefer to use some kind of hardware description language.

There are a few options to do similar things with PCB layout, including tscircuit. There’s a walk-through for using it to create an LED matrix and you can even try it out online, if you like. If you’re more of a visual learner, there’s also an introductory video you can watch below.

The example project imports a Pico microcontroller and some smart LEDs. They do appear graphically, but you don’t have to deal with them graphically. You write “code” to manage the connections. For example:

<trace from={".LED1 .GND"} to="net.GND" />

If that looks like HTML to you, you aren’t wrong. Once you have the schematic, you can do the same kind of thing to lay out the PCB using footprints. If you want to play with the actual design, you can load it in your browser and make changes. You’ll note that at the top right, there are buttons that let you view the schematic, the board, a 3D render of the board, a BOM, an assembly drawing, and several other types of output.

Will we use this? We don’t know. Years ago, designers resisted using HDLs for FPGAs, but the bigger FPGAs get, the fewer people want to deal with page after page of schematics. Maybe a better question is: Will you use this? Let us know in the comments.

This isn’t a new idea, of course. Time will tell which HDLs will survive and which will whither.

In this series of 23 YouTube videos [Rich] puts the AMD Zynq-7000 SoC through its paces by building a development board from the ground up to host it along with its peripherals. The Zynq is part FPGA and part CPU, and while it has been around for a while, we don’t see nearly as many projects about it as we’d like.

Rich covers everything from the power system to HDMI, USB, DDR RAM, and everything in between. By the end, he’s able to boot PetaLinux.

The Zynq SoC includes an ARM Cortex-A9 Based APU and an Artix-7 FPGA (or a Kintex-7 FPGA on higher models). In case you missed it, Xilinx was recently acquired by AMD, which is why you might have remembered this as a Xilinx part.

We’ve heard from [Rich] before. Back in 2021 we saw his Arduino Brings USB Mouse To Homebrew Computer. Don’t miss his follow-up playlist: Building on my Zynq-7000 in which he takes his Zynq-7000 board even further.

If you’re interested in FPGA technology but need something more easy going to get you started, be sure to check out how to build a 6809 CPU on an FPGA. Or, if you need something even simpler, report for boot camp.

Thanks to [Alex] for the tip!

This fun PCB from [Nick Brown] features a miniature railroad implemented with 0805-sized LEDs. With an eye towards designing his own fun interactive PCB badge, the Light-Rail began its journey. He thoroughly documented his process, from shunting various late-night ideas together to tracking down discrepancies between the documentation of a part and the received part.

Inspired by our very own Supercon 2022 badge, he wanted to make a fun badge with a heavy focus on the aesthetics of the final design. He also wanted to challenge himself some in this project, so even though there are over 100 LEDs, they are not laid out in a symmetrical or matrix pattern. Instead, it’s an organic, winding railroad with crossings and stations throughout the board. Designed in KiCad the board contains 144 LEDS, 3 seven-segment displays, and over a dozen buttons that all come together in use for the built in game.

The challenges didn’t stop at just the organic layout of all those LEDs. He decided to use Rust for this project, which entailed writing his own driver for the seven-segment displays as well as creating a tone library for the onboard buzzer. As with all projects, unexpected challenges popped up along the way. One issue with how the oscillator was hooked up meant he wasn’t able to use the ATmega32U4, which was the brains of the entire railroad. After some experimenting, he came up with a clever hack: using a pogo pin jig to connect the clock where it needed to go while programming the board.

Be sure to check out all the details of this journey in his build log. If you love interactive badges also check out some of the other creative boards we’ve featured.