Payphone Tag Is Australia’s New National Sport

April 28, 2026 by Zoe Skyforest No comments

Australia’s payphones are an iconic part of the national landscape, even if they’re not as important as they once used to be. However, they’re having a resurgence of late, in part thanks to a new national pastime—the sport of Payphone Tag!

Created by [Alex Allchin], the game is simple. To play, you first sign up on the website and get your emoji and 5-digit PIN. You then go out and find a payphone, dial the Payphone Tag number, and enter your PIN when prompted. This lets you “capture” the phone, raising your score in the game. If a phone is already captured, no matter—just head out there, dial the number, and key in your own PIN to steal it. You can also push your score even higher by capturing three payphones in a triangle on the map to get bonus points.

It’s a fun geospatial game that’s also free to play, because Telstra made payphone calls free back in 2022. It might cost you a bit to get out to some phones, but there are plenty you can reach with the aid of free public transport at the moment, anyway. Protip—at the time of writing, there are a ton of easy captures to be had on Kangaroo Island. It might just cost you a pretty penny to get out there. Have at it!

We’d love to see some stats from Telstra as to whether this is making a dent in overall payphone usage rates. In any case, there were 800 players in the last 7 days and a full 36,640 captures so far, so a lot is happening out there. We fully expect to see this concept spread to other nations in turn, though it might be less attractive in places where you still need to dig out a coin to make a call.

We’ve featured a few payphone hacks over the years. If you’re doing something rad with these telecommunication devices of yesteryear, we’d love to hear about it on the tipsline.

2026 Green Powered Challenge: Supercapacitor Enables High-Power IoT

April 28, 2026 by Bryan Cockfield No comments

With all the battery technologies and modern low-current sleep modes in most microcontrollers, running a sensor and microcontroller combo off-grid and far away from any infrastructure is usually not too difficult a task. Often these sorts of systems can go years without maintenance or interaction. But for something that still has to be off-grid but needs to do some amount of work every now and then like actuating a solenoid or quickly turning a servo, these battery-based systems can quickly run out of juice. To solve that problem, [Nelectra] has come up with this high-power capacitor-based IoT system.

Although supercapacitors don’t tend to have the energy density of batteries, they’re perfectly capable of powering short tasks in off-grid situations like this. They’re also typically able to tolerate lower voltages, extreme temperatures, and shock better than most batteries as well. A small solar cell on the top of this device keeps it topped up, and when running in deep sleep mode can hold a charge for up to six days. In more real-world applications supporting sensors, relays, or other actuators, [Nelectra] has found that it can hold a charge for around three days. When a quick burst of power is needed, it can deliver 1.5 A at 9 V or 500 mA at 24 V.

[Nelectra]’s stated goal for this build is to bridge low-power energy harvesting and practical field actuation, enabling maintenance-free systems such as irrigation control and remote switching without batteries, going beyond simple sensor applications while not relying on always-on power from somewhere else. Something like this would work really well in applications like this automated farm, which has already provided some unique solutions to intermittent power and microcontroller applications that need very high reliability.

Hackaday Europe: Last Round Of Speakers, Workshops

April 28, 2026 by Elliot Williams No comments

If you don’t already have your tickets to Hackaday Europe, pick them up now. The clock is ticking! Today, we’d like to announce our keynote speaker, the remainder of our featured talks, and two more workshops. (And if you want workshop tickets, which always go fast, get those soon!)

Hackaday Europe is super excited to welcome back Hackaday Superfriend [Sprite_tm] to kick off the event with a keynote talk on how he made a retrogaming PC from bare silicon. Don’t miss it.

Jeroen Domburg

Building a retro-PC…From Components

What if you could build a retro-gaming PC from bare chips? No emulation. No ancient hardware. Jeroen walks through designing a compact 486 SBC with modern amenities, starting from the silicon up.

Edwin Hwu
PlayStation 4 to Psychometer: Skin Nanotexture Biometrics

Turn a PlayStation 4 optical pickup into a high-speed dermal atomic force microscope. Edwin shows how hardware hacking and deep learning combine to assess skin conditions and potentially detect stress non-invasively.

Erin Kennedy
Outdoors with Robots: Adventures and Lessons Learned

Ten years of taking robots into the real outdoors, through sand, mud, and wildfire zones. Erin shares what happens when nature-inspired machines meet nature itself, and what she’s learned building them.

Stephen Coyle
Making physically intuitive electronic instruments

Our physical intuitions about inertia, momentum, and gravity shape how we play instruments. Stephen explores what happens when digital instruments simulate these properties and what new musical possibilities emerge.

Sylvain Huet
Bare metal made easy

As tech grows more opaque, there’s an urgent need to return to simple, hackable systems. Sylvain presents an ambient computing vision; devices that blend into life rather than dominate it.

Alex Ren
Hack Club: How to get 2000 teenagers hacking their own hardware projects

A 3D printer made of Lego. DOOM running in a PDF. These are Hack Club projects built by teenagers. Alex shares the tools, culture, and community behind hardware hacking at scale for young makers.

Michael Wiebusch
Build a Cable Modem for your Arduino. For 2 Euros. But it’s not a Modem.

Electric signals travel in two directions in a coaxial cable, and they don’t mix on the way. Michael explains transmission line theory and demonstrates why it matters for RF and high-speed digital design.

Anders Nielsen
High Performance SDR on the cheap

RF, high-speed USB, analog chaos. Building a 20MHz continuous bandwidth, 3GHz-capable SDR without breaking a $50 BOM, achievable with a single FPGA on a carrier board.

Federico Terraneo
Fluid kernels and how to optimize C++ for microcontrollers

A 20-minute tour of the fluid kernel architecture, the Miosix RTOS as a practical implementation, and 18 years of hard-won tips for writing efficient C++ on microcontrollers.

Benjaminas Sulcas
Fault injection 101

A hands-on workshop covering the basics of hardware fault injection, power glitching, EMFI, and practical comparisons of tools available to hardware security researchers and curious makers.

Davide Gomba
Let’s Mesh!

A practical dive into mesh networking with Meshtastic and Reticulum; installing, configuring, and communicating across decentralized mesh programs. Leave with hands-on experience and a new view of off-grid connectivity.

If you’re joining us and you’re not on the list above, you can still take the stage! We’ll have time for seven-minute Lightning Talks, hopefully enough for everyone. So bring your hack and bring a story. We want to hear it.

[If you read this far, you probably want tickets. Just sayin’.]

A Tube Amplifier That’s Oven Ready

April 28, 2026 by Jenny List 15 Comments

The problem with tube based audio is that it has so often been hijacked by people for whom the bragging rights of having a tube amplifier outweigh the benefits, or the sheer fun of building the thing. [Bettina Neumryr] makes a speciality of building projects featured in old electronics magazines, and her latest, a tube amplifier from 1955, is a fantastic antidote to the gold-plated silliness of audiophile tube amplifiers.

Design wise it’s relatively straightforward, with a preamplifier before a two-tube transformerless splitter circuit driving a push-pull output. She dives into the circuit a little, noting its feedback circuit to the cathode of the first splitter tube. There’s an accompanying power supply, a classic tube rectifier design that incorporates a hefty low-pass filter with a giant choke.

We particularly like her choice of chassis — while it’s possible to pay silly money for a tube chassis in 2026 she’s taken a much more down to earth approach with a pair of baking trays. We’re being honest here, they look surprisingly good. Component choices are limited by what’s available so most parts come from the junk box including the output transformer which causes her issues later. There’s a lot of mumbo-jumbo about tube amplifier layout, and she wisely sidesteps some of it.

The result after a few mishaps and a bit of unintended oscillation, is an amp which shows promise, but has distortion due to that transformer. We think she’ll have no problems sourcing a better one, which should bring that distortion figure into the acceptable range. You can watch the whole video below the break, and if that’s got you hooked, you can see one of our own youthful follies.

Continue reading “A Tube Amplifier That’s Oven Ready” →

The GPS III Rollout Is Almost Complete, But What Is It?

April 28, 2026 by Tom Nardi 12 Comments

Considering how integral it is to our modern way of life, you could be excused for thinking that the Global Positioning System (GPS) is a product of the smartphone era. But the first satellites actually came online back in 1978, although the system didn’t reach full operational status until April of 1995. While none of the active GPS satellites currently in orbit are quite that old, several of them were launched in the early 2000s — and despite a few tweaks and upgrades, their core technology isn’t far removed from their 1990s era predecessors.

But in the coming years, that’s finally going to change. Just last week, the tenth GPS III satellite was placed in orbit by a SpaceX Falcon 9 rocket. Once it’s properly configured and operational, it will join its peers to form the first complete “block” of third-generation GPS satellites. Over the next decade, as many as 22 revised GPS III satellites are slated to take their position over the Earth, eventually replacing all of the aging satellites that billions of people currently rely on.

So what new capabilities do these third-generation GPS satellites offer, and why has it taken so long to implement needed upgrades in such a critical system?

Continue reading “The GPS III Rollout Is Almost Complete, But What Is It?” →

New Slicer Enables Horizontal Overhangs Without Support

April 28, 2026 by Zoe Skyforest 12 Comments

There’s a rule of thumb when it comes to FDM printing that overhangs are really only possible to an angle of around 45 degrees or so. If you try to squirt out plastic with nothing supporting it, it just goes everywhere. However, a new slicer hopes to enable printing up to 90-degree overhangs with some creative techniques.

The software that enables this is called WaveOverhangs, and currently exists as a fork of OrcaSlicer. The idea is straightforward enough — using unique toolpathing to create rings of deposited material that fasten to those laid down before them in the same layer. Thus as the printer lays down a layer into bare space, the deposited plastic is, ideally, able to fix on to the supported edge. As the next ring is laid down, it grabs on to the cooled ring laid down before it, and so on. The idea is inspired by wave propagation, hence the name. You can see a demonstration of the software in the video below by [Cocoanix 3D Printing].

It’s still a very new technique. The slicer has a whole bunch of knobs to turn and two different algorithms. Get the settings just right and you can print horizontal overhangs successfully. There aren’t exactly presets yet, this is something to explore with trial and error. If you test it out, don’t forget to upload your results to the Community Gallery so the developers can see what works and what doesn’t.

We’ve explored how smart slicers can do amazing things before, too, particularly when it comes to things like bridging.

Continue reading “New Slicer Enables Horizontal Overhangs Without Support” →

A Guide To CubeSat Mission And Bus Design

April 28, 2026 by Al Williams 8 Comments

If you mention the word bus, you might think of public transportation or, more likely for us, a way to connect things together. But in the satellite world, the bus is the part of a vehicle that supports the payload but isn’t itself the payload. Typically, that means the electric power system, propulsion, radios, and thermal control, among other systems. If you are designing a CubeSat, you will want to read A Guide to CubeSat Mission and Bus Design by [Frances Zhu].

The Creative Commons-licensed book has twelve chapters, ranging from systems engineering — that is, defining what you want to do — to analyzing structures, handling power, setting up communications, and more. Of particular interest to us was the chapter on command and data handling. The final chapters cover software, system integration, and there’s even a chapter on Ethics.

If you want to build a CubeSat or just want to learn more about how satellites actually work, this is a great read. There are videos and other features, too. If you don’t like reading in your browser, you can download an EPUB, PDF, or MOBI near the top of the page.

There are many resources for the want-to-be CubeSat builder. You can even start with an open source design.