Author: Seth Mabbott

12 Articles

Breadboard for vacuum tubes

This Board Helps You Prototype Circuits With Tubes

September 14, 2025 by 11 Comments

There you are at the surplus store, staring into the bin of faded orange, yellow, red, and black, boxes–a treasure trove of vintage vacuum tubes—dreaming about building a tube amp for your guitar or a phonograph preamp for your DIY hi-fi sound system. But, if you are not already in possession of a vintage, purpose-built tube testing device, how would you test them to know whether they are working properly? How would you test out your designs before committing to them? Or maybe your goal is simply to play around and learn more about how tubes work.

One approach is to build yourself a breadboard for tubes, like [MarceloG19] has done. Working mostly with what was laying around, [MarceloG19] built a shallow metal box to serve as a platform for a variety of tube sockets and screw terminals. Connecting the terminals to the socket leads beneath the outer surface of the box made for a tidy and firm base on which to connect other components. The built-in on/off switch, fuse and power socket are a nice touch.

[MarceloG19’s] inaugural design is a simple Class A amplifier, tested with a sine wave and recorded music. Then it’s on to some manual curve tracing, to test a tube that turns out to be fairly worn-out but serviceable for certain use cases.

If you’re dipping your toes into tube-based electronics, you’re going to want a piece of equipment like this prototyping board and [MarceloG19’s] documentation and discussion are a good read to help get you started.

Once you have your board ready, it’s time to move on to building a stereo amplifier , a tube-based headphone preamp, or take things in a different direction with this CRT-driven audio amplifier.

Business Card Ouija board

This Ouija Business Card Helps You Speak To Tiny Llamas

September 9, 2025 by 7 Comments

Business cards, on the whole, haven’t changed significantly over the past 600-ish years, and arguably are not as important as they used to be, but they are still worth considering as a reminder for someone to contact you. If the format of that card and method of contact stand out as unique and related to your personal or professional interests, you have a winning combination that will cement yourself in the recipient’s memory.

In a case study of “show, don’t tell”, [Binh]’s business card draws on technological and paranormal curiosity, blending affordable, short-run PCB manufacturing and an, LLM or, in this case, a Small Language Model, with a tiny Ouija board. While [Binh] is very much with us in the here and now, and a séance isn’t really an effective way to get a hold of him, the interactive Ouija card gives recipient’s a playful demonstration of his skills.

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Improved Jumping Bean

2025 One Hertz Challenge: Building A Better Jumping Bean

July 17, 2025 by 4 Comments

Do you feel nostalgia for a childhood novelty toy that had potential but ultimately fell short of its promise? Do you now have the skills to go make a better version of that toy to satisfy your long-held craving? [ExpensivePlasticCrap] does and has set off on a mission to make a better jumping bean.

Jumping beans, the phenomenon on which the novelty of [ExpensivePlasticCrap]’s childhood is based, are technically not beans, and their movement is arguably not a jump — a small hop at best. The trick is that the each not-a-bean has become the home to moth larvae that twitches and rolls on the ground as the larvae thrash about, trying to move their protective shells out of the hot sun.

The novelty bean was a small plastic pill-like capsule with a ball bearing inside what would cause the “bean” to move in unexpected ways as it rolled around. [ExpensivePlasticCrap]’s goal is to make a jumping bean that lives up to its name.

Various solenoids and motors were considered for the motion component of this new and improved bean. Ultimately, it was a small sealed vibrating motor that would be selected to move the bean without getting tangled in what was to become a compact bundle of components.

An ATtiny microcontroller won out over discrete components for the job of switching the motor on and off (once per second), for ease of implementation. Add this along with a MOSFET, battery and charging board for power into a plastic capsule, and the 1  Hz jumping bean was complete.

[ExpensivePlasticCrap] offers some thoughts on how to get more jump out of the design by reducing the weight of the build and giving it a more powerful source of motion.

If insect-inspired motion gets you jumping, check out this jumping robot roach and these tiny RoboBees.

2025 Hackaday One Hertz Challenge
navdesk

DIY Navigation System Floats This Boat

July 10, 2025 by 10 Comments

[Tom] has taken a DIY approach to smart sailing with a Raspberry Pi as the back end to the navigation desk on his catamaran, the SeaHorse. Tucked away neatly in a waterproof box with a silicone gasket, he keeps the single board computer safe from circuit-destroying salt water. Keeping a board sealed up so tightly also means that it can get a little too warm. Because of this he under-clocks the CPU so that it generates less heat. This also has the added benefit of saving on power which is always good when you aren’t connected to the grid for long stretches of time.

A pair of obsolescent phones and a repurposed laptop screen provide display surfaces for his navdesk. With these screens he has weather forecasts, maps, GPS, depth, speed over ground — all the data from all the onboard instruments a sailor could want to stream through a boat’s WiFi network — at his fingertips.

There’s much to be done still. Among other things, he’s added a software defined radio to the Pi to integrate radio monitoring into the system, and he’s started experimenting with reprogramming a buoy transmitter, originally designed for tracking fishing nets, so that it can transmit his boat’s location, speed and heading instead.

The software that ties much of this system together is the open source navigational platform OpenCPN which, with its support for third-party plugins, looks like a great choice for experimenting with new gadgets like fishing net buoy transmitters.

For more nautical computing fun check out this open source shipboard computer, and this data-harvesting, Arduino-driven buoy.

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Turbo engine mockup

3D Printer Turbo-Charges A Vintage Vehicle

July 4, 2025 by 21 Comments

[Ryan] of [Fat Lip Collective] has been on a streak of using 3D printing for his car mod projects. From spark plug adapters to exhaust pipes to dash panels, his CAD skills and additive manufacturing tech have played a number of roles in his process.

Most recently, [Ryan] has embarked on a mission to equip an ’80s-era Toyota KE70 Corolla with a turbo engine. The main question there being how to fit the engine back into the car once he’s inserted a salvaged turbo into the exhaust line.

There is a non-trivial amount of stuff that needs to be packed in with the rest of the engine and finding a working configuration that doesn’t get in the way of anything else requires some trial and error. Furthermore, the alignment of the many twisting and turning pieces of schedule 40 pipe that will direct gasses where they need to go needs to be pretty precise.

Juggling all of this would be tedious, time consuming, and error prone if it were not for [Ryan’s] mighty 3D printer. He printed a set of the different elbows and reducers modeled on the schedule 40 pipe that he would likely be using. He added degree markers for easy reference later and flat sections at the ends of each piece so they could be bolted to each other. With this kit of parts in hand, he was able to mock up different arrangements, re-configuring them as he considered the position of other nearby components.

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Drone Photogrammetry

Photogrammetry Takes To The Skies

June 22, 2025 by 14 Comments

Maybe your goal is to preserve the heyday of rail travel with a precise scale replica of a particular railroad station. Maybe you’re making a hyper-local edition of Monopoly in which the houses and hotels are the actual houses and hotels in your hometown.

Whatever the reason, if you have need for shrinkifying a building or other reasonably large object, there is (at least) one sure-fire way to do it, and [ nastideplasy ] is your guide with this tutorial on drone photogrammetry.

The process is essentially the same as any other photogrammetry you may have seen before—take lots of overlapping photos of an object from many different angles around it, stitch those photos together, make a 3D mesh by triangulating corresponding points from multiple photos—but this time the photos are captured by drone, allowing for much larger subjects, so long as you can safely and legally fly a drone around it.

The challenge, of course, is capturing a sufficient number of overlapping photos such that your reconstruction software can process them into a clean 3D mesh. Where purpose-built 3D scanners, automatic turntables, or a steady hand and lots of patience worked well at a smaller scale, skill with a pair of control sticks is the key to getting a good scan of a house.

[ nastideplasy ] also points out the importance of lighting. Direct sunlight and deep shadows can cause issues when processing the images, and doing this at night is almost certainly out of the question. Overcast days are your best bet for a clean scan.

The tutorial calls for software from Autodesk to stitch photos and clean up 3D meshes. We’ve also seen some excellent results with open source options like Meshroom as well.

Capacitor Adapter board

Kludge Compensates For Kaput Component With Contemporary Capacitor

June 16, 2025 by 14 Comments

It is a well-known reality of rescuing certain older electronic devices that, at some point, you’re likely going to have to replace a busted capacitor. This is the stage [Kevin] is at in the 3rd installment in his saga of reviving a 50-year-old Military Tektronix oscilloscope.

[Kevin] recently discovered a failed capacitor in the power supply for this vintage analog scope. Having identified and removed the culprit, it was time to find a way to replace the faulty component with a modern equivalent. The original capacitor is out of fashion to the degree that a perfect replacement would be impractical and likely not desirable. This job would call for a bit of adaptation.

Continue reading “Kludge Compensates For Kaput Component With Contemporary Capacitor” →