Author: Tyler August

236 Articles

PLA Gears Fail To Fail In 3D Printed Bicycle Drivetrain

October 10, 2025 by 33 Comments

Anyone who has ever snapped a chain or a crank knows how much torque a bicycle’s power train has to absorb on a daily basis; it’s really more than one might naively expect. For that reason, [Well Done Tips]’s idea of 3D printing a gear chain from PLA  did not seem like the most promising of hacks to us.

Contrary to expectations, though, it actually worked; at the end of the video (at about 13:25), he’s on camera going 20 km/h, which while not speedy, is faster than we thought the fixed gearing would hold up. The gears themselves, as you can see, are simple spurs, and were modeled in Fusion360 using a handy auto-magical gear tool. The idler gears are held in place by a steel bar he welded to the frame, and are rolling on good old-fashioned skateboard bearings–two each. (Steel ones, not 3D printed bearings.) The healthy width of the spur gears probably goes a long way to explaining how this contraption is able to survive the test ride.

The drive gear at the wheel is steel-reinforced by part of the donor bike’s cassette, as [Well Done Tips] recognized that the shallow splines on the freewheel hub were not exactly an ideal fit for PLA. He does complain of a squeaking noise during the test ride, and we can’t help but wonder if switching to helical gears might help with that. That or perhaps a bit of lubricant, as he’s currently riding the gears dry. (Given that he, too, expected them to break the moment his foot hit the pedal, we can’t hardly blame him not wanting to bother with grease.)

We’ve seen studies suggesting PLA might not be the best choice of plastic for this application; if this wasn’t just a fun hack for a YouTube video, we’d expect nylon would be his best bet. Even then, it’d still be a hack, not a reliable form of transportation. Good thing this isn’t reliable-transportation-a-day!

Continue reading “PLA Gears Fail To Fail In 3D Printed Bicycle Drivetrain” →

Motors Make The Best Knobs With SimpleFOC

October 9, 2025 by 17 Comments

The worst thing about a volume knob is that, having connected it to a computer, it might be wrong: if you’ve manually altered the volume settings somewhere else, the knob’s reading won’t be correct. [I Got Distracted] has a quick tutorial on YouTube showing how to use a BLDC, a hall effect sensor, Pi Pico and the SimpleFOC library to make a knob with active haptic feedback and positioning.

We covered the SimpleFOC library a few years ago, but in case you missed it, it’s, well, a simple library for FOC on all of our favorite microcontrollers, from Arduino to ESP to Pico. FOC stands for field-oriented control, which is a particular way of providing smooth, precise control to BLDCs. (That’s a BrushLess DC motor, if the slightly-odd acronym is new to you.) [I Got Distracted] explains exactly how that works, and shows us just how simple the SimpleFOC project is to use in this video.  Why, they even produce their own motor controllers, for a fully-integrated experience. (You aren’t restricted to that hardware, but it certainly does make things easy.)

The haptic feedback and self-dialing knob make for an easy introductory project, but seeing how quick it hacks together, you can doubtless think of other possibilities. The SimpleFOC controller used in this video is limited to relatively small motors, but if you want to drive hundreds of kilowatts through open source hardware, we’ve covered that, too.  

Arguably, using a motor as a knob isn’t within the design spec, and so could almost qualify for our ongoing Component Abuse Challenge, had [I Got Distracted] thought to enter.

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2025 Component Abuse Challenge: The Sweet Sound Of A Choking Transformer

October 9, 2025 by 13 Comments

The Component Abuse Challenge is dragging all sorts of old, half-forgotten hacks out of the woodwork, but this has got to be the most vintage: [KenS] started using a transformer as a variable choke on his speakers 55 years ago.

The hack is pretty bone-dead simple. A choke is an inductor in an audio (or any other) circuit designed to, well, choke off higher-than-desired frequencies. We featured a deep dive a few years back if you’re interested. An inductor is a coil of wire, usually (but not necessarily) wound around a core of iron or ferrite. A transformer? Well, that’s also a coil of wire around a core… plus an extra coil of wire. So when [KenS], back in his salad days, had a tweeter that a was a little too tweety, and no proper choke, he grabbed a transformer instead.

This is where inspiration hit: sure, if you leave the second winding open, the transformer acts like a standard choke. What happens if you short that second winding? Well, you dampen the response of the first winding, and it stops choking, to the point that it acts more like a straight wire. What happens if you don’t short the second winding, but don’t leave it wide open? [KenS] stuck a potentiometer on there, and found it made a handy-dandy variable choke with which to perfectly tune the tone response of his speakers. Changing the resistance changes the rate at which high frequencies are choked off, allowing [KenS] to get the perfect frequency response with which to rock out to Simon & Garfunkel, The Carpenters and The Guess Who. (According to the Billboard Top 100 for 1970, those are who you’d be listening to if you had conventional tastes.)

While we can’t say the transformer is really being tortured in this unusual mode, it’s certainly not how it was designed, so would qualify for the “Junk Box Substitutions” category of the Component Abuse Challenge. If you’ve made similar substitutions you’d like to share, don’t wait another 55 years to write them up– the contest closes November 11th.

Transformer image: Hannes Grobe, CC BY-SA 4.0.

2025 Hackaday Component Abuse Challenge

2025 Component Abuse Challenge: Load Cell Anemometer

October 9, 2025 by 22 Comments

When you think anemometer, you probably don’t think “load cell” — but (statistically speaking) you probably don’t live in Hurricane Country, which is hard on wind-speed-measuring-whirligigs. When [BLANCHARD Jordan] got tired of replacing professionally-made meteorological eggbeaters, he decided he needed something without moving parts. Whatever he came up with would probably qualify for the Component Abuse Challenge, but the choice of load cells of all things to measure wind speed? Yeah, that’s not what the manufacturer intended them for.

In retrospect, it’s actually a fairly obvious solution: take a plate of known area, and you’re going to get a specific force at a given air speed. The math isn’t hard, it’s just not how we normally see this particular measurement done. Of course, a single plate would have to be pivoted to face the wind for an accurate reading, which means moving parts– something specifically excluded from the design brief. [Jordan] instead uses a pair of load cells, mounted 90 degrees to one another, for his anemometer. One measures the force in a north-south axis, and the other east-west, allowing him to easily calculate both wind speed and direction. In theory, that is. Unfortunately, he vibe coded the math with ChatGPT, and it looks like it doesn’t track direction all that well. The vibe code runs on an ESP32 is responsible for polling data, tossing outliers, and zeroing out the load cells on the regular.

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A Childhood Dream, Created And Open Sourced

October 7, 2025 by 12 Comments

Some kids dream about getting a pony, others dream about a small form factor violin-style MIDI controller. [Brady Y. Lin] was one of the latter, and now, with the skills he’s learning at Northwestern, he can make that dream a reality — and share it with all of us as an open source hardware project.

The dream instrument’s name is Stradex1, and it’s a lovely bit of kit. The “fretless” neck is a SoftPot linear potentiometer being sampled by an ADS1115 ADC — that’s a 16-bit unit, so while one might pedantically argue that there are discreet frets, there’s 2^15 of them, which is functionally the same as none at all. Certainly it’s enough resolution for continuous-sounding pitch control, as well as vibrato, as you can see at 3:20 in the demo video below. The four buttons that correspond to the four strings of a violin aren’t just push-buttons, but also contain force sensors (again, sampled by the 16-bit ADC) to allow for fine volume control of each tone.

A few other potentiometers flesh out the build, allowing control over different MIDI parameters, such as what key [Brady] is playing on. The body is a combination of 3D printed plastic and laser-cut acrylic, but [Brady] suggests you could also print the front and back panels if you don’t happen to have a laser cutter handy.

This project sounds great, and it satisfies the maker’s inner child, so what’s not to love. We’ve had lots of MIDI controllers on Hackaday over the years — everything from stringless guitars  to wheel-less Hurdy-Gurdies to say nothing of laser harps galore — but somehow, we’ve never had a MIDI violin. The violin hacks we have featured tend to be either 3D printed or comically small.

If you like this project but don’t feel like fabbing and populating the PCB, [Brady] is going to be giving one away to his 1000th YouTube subscriber. As of this writing, he’s only got 800, so that could be you!

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2G Gone? Bring It Back Yourself!

October 6, 2025 by 25 Comments

Some parts of the world still have ample 2G coverage; for those of in North America, 2G is long gone and 3G has either faded into dusk or beginning its sunset. The legendary [dosdude1] shows us it need not be so, however: Building a Custom 2G GSM Cellular Base Station is not out of reach, if you are willing to pay for it. His latest videos show us how.

Before you start worrying about the FCC or its equivalents, the power here is low enough not to penetrate [dosdude]’s walls, but technically this does rely in flying under the radar. The key component is a Nuand BladeRF x40 full-duplex Software Defined Radio, which is a lovely bit of open-source hardware, but not exactly cheap. Aside from that, all you need is a half-decent PC (it at least needs USB-3.0 to communicate with the SDR, the “YateBTS”  software (which [dosdude1] promises to provide a setup guide for in a subsequent video) and a sim card reader. Plus some old phones, of course, which is rather the whole point of this exercise.

The 2G sunset, especially when followed by 3G, wiped out whole generations of handhelds — devices with unique industrial design and forgotten internet protocols that are worth remembering and keeping alive. By the end of the video, he has his own little network, with the phones able to call and text one another on the numbers he set up, and even (slowly) access the internet through the miniPC’s network connection.

Unlike most of the hacks we’ve featured from [dosdude1], you won’t even need a soldering iron, never mind a reflow oven for BGA. 

Continue reading “2G Gone? Bring It Back Yourself!” →

GuitarPie Uses Guitar As Interface, No Raspberries Needed

October 6, 2025 by 14 Comments

We’ve covered plenty of interesting human input devices over the years, but how about an instrument? No, not as a MIDI controller, but to interact with what’s going on-on screen. That’s the job of GuitarPie, a guitar-driven pie menu produced by a group at the University of Stuttgart.

The idea is pretty simple: the computer is listening for one specific note, which cues the pie menu on screen. Options on the pie menu can be selected by playing notes on adjacent strings and frets. (Check it out in action in the video embedded below). This is obviously best for guitar players, and has been built into a tablature program they’re calling TabCTRL. For those not in the loop, tablature, also known as tabs, is an instrument-specific notation system for stringed instruments that’s quite popular with guitar players. So TabCTRL is a music-learning program, that shows how to play a given song.

With this pairing, you can rock out to the tablature, the guitarist need never take their hands off the frets. You might be wondering “how isn’t the menu triggered during regular play”? Well, the boffins at Stuttgart thought of that– in TabCTRL, the menu is locked out while play mode is active. (It keeps track of tempo for you, too, highlighting the current musical phrase.) A moment’s silence (say, after you made a mistake and want to restart the song) stops play mode and you can then activate the menu. It’s well a well-thought-out UI. It’s also open source, with all the code going up on GitHub by the end of October.

The neat thing is that this is pure software; it will work with any unmodified guitar and computer. You only need a microphone in front of the amp to pick up the notes. One could, of course, use voice control– we’ve seen no shortage of hacks with that–but that’s decidedly less fun. Purists can comfort themselves that at least this time the computer interface is a real guitar, and not a guitar-shaped MIDI controller. Continue reading “GuitarPie Uses Guitar As Interface, No Raspberries Needed” →