Mysterious Files PH

If a zipper breaks, a 3D printer might not be the first tool one reaches for — but it’s more feasible than one might think. [MisterJ]’s zipper slider replacement is the kind of 3D print that used to be the domain of well-tuned printers only, but most hobbyist printers should be able to handle it nowadays.

What really sets this design apart from other printed versions is its split construction. Putting a new slider onto a zipper usually requires one to free the ends of the zipper by unsewing them. [MisterJ]’s two-part design instead allows the slider to be assembled directly onto the zipper, without the hassle of unsewing and re-sewing anything. That’s a pretty significant improvement in accessibility.

Want to make some adjustments? Good news, because the files are in STEP format which any CAD program will readily understand. We remember when PrusaSlicer first gained native STEP support and we’re delighted that it’s now a common feature in 3D printer software.

[MisterJ]’s zipper slider design is available in a variety of common sizes, in both standard (zipper teeth face outward) and reverse (zipper teeth face inward) configurations. Naturally a metal slider is more durable than a plastic one, but being able to replace broken parts of a zipper with a 3D printer is a pretty handy thing. Speaking of which, you can also 3D print a zipper box replacement should the squarish bit on the bottom get somehow wrecked or lost.

[idealdealy] had a problem. GNU Radio Companion was proving to be a powerful tool, but it just didn’t look… cool enough. The solution? A custom bit of software called PimpMyGRC, designed to jazz things up a bit in everyone’s favorite open-source SDR package.

In the creator’s own words, PimpMyGRC solves the problem nobody had with GNU Radio. It stemmed from [idealdealy]’s desire to have a plain black background in the software to ease eye strain during late night debug sessions. From there, it developed into a full theming package coded in Python, complete with all kinds of fun color schemes.

You can go with “arctic” if you’re somewhere cold, “bubblegum” if you’re feeling young and fun, or “neon hacker” if you’re still obsessed with early 90s movies with terrible plot holes around computers.

None of these themes will help you work faster, but they’ll probably make your friends jealous that your setup looks a little bit cooler than theirs. Plus, there are some really fun animated effects to catch your eye if your attention is fading. You might get flames dancing on the bottom of the screen, or binary digits falling through the display in a manner vaguely akin to terminals from The Matrix.

If you’re new to this world, you might like to check out this primer on getting started with GNU Radio. Meanwhile, if you’re cooking up your own SDR hacks of value, don’t hesitate to notify the tipsline!

It’s Pi Day, and while we know that many of you celebrate privately, those that take a moment to put aside their contemplation of all things circular and join us on this mathematically-significant day will likely know the name [Cristiano Monteiro]. Since 2022 he’s made it a yearly tradition to put together a themed project every March 14th, and he’s just put the finishing touches on the 2026 edition.

Generally, [Cristiano] sends in some interesting hardware device that visualizes the calculation of pi, but this year he surprised us a bit by delivering a software project. His Orbital Pi Simulator allows you to see what would happen to an orbiting spacecraft if it’s navigation system suddenly believed the value of pi was something different.

In broad strokes, we can imagine what would happen. If you plug in something significantly higher than 3.14, the orbit becomes elliptical to the point that the craft can fly off into deep space. Drop the value down, and the orbit will intersect with the Earth — a guaranteed recipe for a bad time.

The Kerbal Space Program players in the audience will no doubt point out that a spacecraft in a stable orbit would more or less stay on that same trajectory indefinitely and not need to manually adjust its velocity in the first place. Further, they would argue that said spacecraft suddenly firing its thrusters retrograde because a flipped bit in its computer resulted in the value of pi suddenly being 1.2 isn’t very realistic. Those people would be correct, but they would also be no fun at parties.

Fans of math and/or circles will no doubt be interested in the previous devices [Cristiano] has built to mark this date. Last year he put together a robotic hand that counted out pi with its 3D printed fingers, and in 2024 he used the Pepper’s Ghost illusion to great effect. For those wondering, not everything he does is pi-related. The portable GPS time server he sent out way in 2021 was a particularly slick piece of hardware.

Cooking with charcoal is a fairly common human activity, as much as others have come to prefer fuels like propane and propane accessories for their outdoor, summertime grilling. Although it’s made from wood, it has properties that make it much more useful for cooking — including burning at a higher temperature and with more consistent burn rates. It can also be used as a fuel for generating heat and electricity, but since it’s not typically found lying around in the forest it has to be produced, which [Greenhill Forge] has demonstrated his charcoal production system in one of his latest videos.

The process for creating charcoal is fairly simple. All that needs to happen is for wood to be heated beyond a certain temperature in the absence of oxygen. At this point it will off-gas the water stored in it as well as some of the volatile organic compounds, and what’s left behind is a flammable carbon residue. Those volatile organics are flammable as well, though, so [Greenhill Forge] uses them to heat the wood in a self-sustaining reaction. First, a metal retort is constructed from a metal ammo box, with a pipe extending from the side and then underneath the box. A few holes are drilled in this part, and the apparatus is mounted above a small fire on a metal stand. With the fire lit the wood begins heating, and as it heats these compounds exit the pipe and ignite, adding further fuel to the fire. Eventually the small fire will go out, allowing the retort to heat itself on the gasses released from the wood alone.

To generate the hot water, [Greenhill Forge] has taken an extra step and enclosed the retort in a double walled metal cylinder. Inside the cylinder is a copper tube packed in sand, which harvests the waste heat from the charcoal production for hot water. In his test runs, the water in a large drum was heated to the point that the tubing he used for the test began to melt, so it is certainly working better than he expected.

After the retort cools, [Greenhill Forge] uses the charcoal in another process that generates about a days’ worth of electricity and hot water. It’s part of a complete off-grid system that’s fairly carbon neutral, since trees are an abundant renewable resource compared to fossil fuels. Heating with wood directly is still common in many cold areas around the world, with the one major downside being the labor required to keep the stove running. But we’ve seen at least one project which solves this problem as well.

The Tesla turbine is a bladeless centripetal-flow turbine invented by Nikola Tesla in 1913, using the boundary-layer effect rather than having a stream of gases or a fluid impinge on blades. Recently [Jamie’s Brick Jams] constructed one using Lego to demonstrate just how well these turbines work compared to their bladed brethren.

Since it uses the boundary-layer effect, the key is to have as much surface area as possible. This means having many smaller discs stacked side by side with some spacing between them.

Interestingly, the air that is directed against the turbine will travel inwards, towards the axle of the discs and thus requiring some way to vent the air. In the video a number of design prototypes are tested to see how they perform before settling on a design suitable for a functional generator.

The first discs are printed in PLA with an FDM printer, which are put on a shaft with 1 mm spacers. What becomes clear during testing is that these turbines can reach ridiculous speeds, but torque is really quite weak until you hit very high RPMs, well beyond 10,000 RPM. This is a bit of an issue if you want to drive any load with it, especially on start-up, but managed to propel a walker robot as a quick torque test.

After all that testing and experimenting, the right material for the turbine discs was investigated, with PLA pitted against ‘PLA tough’, PETG, PC and TPU. Of these PLA Tough got the best results in terms of RPM at the same air pressure. This was assembled into a basic generator, but the turbine struggled to generate enough torque.

Here the solution was to create a custom generator that would be much easier to spin up. To this was added a much larger turbine with 0.3 mm thin discs, using which ultimately some power could be generated, along with a considerable amount of torque. To adjust the RPM into the generator from the turbine a CVT initially was used to provide a gradual adjustment, but this had to be replaced with metal gears.

After this change the generator was good enough for a power output of about 14 Watt at 30 V with 85 PSI as input. Which is more than enough to charge a smartphone or light up a big LED panel. The design files for all of these turbines are provided on MakerWorld, such as for the big turbine.

Although Tesla turbines never made much of a splash as turbines, they are quite nice as pumps that can take a bit of abuse, including ingesting debris that would wreck other types of pumps. As a turbine they remain a fun hobbyist toy, with us covering various designs over the years. Take for example this one from 2011 based on HDD platters, or a micro turbine out of metal.

Remember those brick cellphones in the 1990s? They were comically large by today’s standards. These phones used the 1G network to communicate and, as such, have been unusable for decades now. However [Alan Boris] has resurrected this classic phone to operate today.

Originally costing as much as today’s top-of-the-line phones, but instead of weighing just a few ounces this classic Motorola DynaTAC 8000 Classic 2 tips the scales at a hefty 1.5 lbs. [Alan Boris] decided to not just bring the electronics back to life, but to even stuff a modern cellphone inside it to make it fully functional. Given the size of this phone, finding room for the new innards wasn’t much of a challenge. In fact, after the retrofit there was less in the phone than when it started life.

Using a perfboard and some tactile switches he was able to sense the button presses on the phone’s keypad and relay those to a Raspberry Pi Pico 2. The Pico in turn drove a small color LCD to replicate the original screen and controlled a pair of ADG729 boards used to dial the BM10 cellphone within this cellphone. The BM10 is a cellphone about the size of a 9V battery, making it easy to put inside the DynaTAC and bring the handset back to the modern cellular network.

Thanks [Alan Boris] for the tip! Be sure to check out our other cellphone hacks as well as some of our other retrofit hacks.

Join Hackaday Editors Elliot Williams and Tom Nardi as they cover their favorite hacks and stories from the week. The episode kicks off with some updates about Hackaday Europe and the recently announced Green Power contest, as well as the proposal of a new feature of the podcast where listeners are invited to send in their questions and comments. After the housekeeping is out of the way, the discussion will go from spoofing traffic light control signals and the line between desktop computers and smartphones, all the way to homebrew e-readers and writing code with chocolate candies. You’ll hear about molding replacement transparent parts, a collection of fantastic tutorials on hardware hacking and reverse engineering, and the recent fireball that lit up the skies over Germany. The episode wraps up with a fascinating look at how the developer of Pokemon Go is monetizing the in-game efforts of millions of players.

Check out the links below if you want to follow along, and as always, tell us what you think about this episode in the comments!

Download this episode in DRM-free MP3 so you can listen to it while doing unpaid labor in Pokemon Go.

News:

• 2026 Hackaday Europe Call For Participation: We Want You!
• Get Your Green Power On!

What’s that Sound?

• Think you know that sound? Fill out the form for a chance to win!

Interesting Hacks of the Week:

• Spoofing An Emergency Traffic Preemption Signal
• Hands On With Creality’s New M1 Filament Maker
  • ERRF 22: Recreator 3D Turns Trash Into Filament
• DIY 3D Pen Is Born To Weld
• Are We Finally At The Point Where Phones Can Replace Computers?
  • Smartphone Hackability, Or, A Pocket Computer That Isn’t
  • Google Will Require Developer Verification Even For Sideloading
• Power Control For A Busy Workbench
• Calculator Case To Scratch-Built Pocket E-Reader

Quick Hacks:

• Elliot’s Picks:
  • Building A Class 100 Semiconductor Cleanroom Inside A Shed
  • The Sweetest Programming Language: MNM
  • A Rotary Dial The 3D Printed Way
• Tom’s Picks:
  • Reverse-Engineering The Bluetooth Fichero Thermal Label Printer Protocol
  • Clear Resin Casting Replicates Old Acrylic For Selectric Repair
  • Take A Ride On Wrongbaud’s Hardware Hacking Highway

Can’t-Miss Articles:

• German Fireball’s 15 Minutes Of Fame
  • The Moon Is Safe, For Now: No Collision In 2032 After All
  • The Solar System Is Weirder Than You Think
  • Accidental Climate Engineering With Disintegrating Satellites
• Pokemon Go Had Players Capturing More Than They Realized