Misc Hacks

4173 Articles

Servo Larson scanner

No LEDs Required For This Servo-Controlled Larson Scanner

February 13, 2022 by 31 Comments

All things considered, it’s pretty easy to get one LED is a strip to light up sequentially, and have it bounce back and forth. Turning that simple animation into a real Larson scanner, with smooth transitions and controlled fade-out, is another thing entirely. And forgetting the LEDs altogether and making a servo-operated Larson scanner is — well, let’s just call it an interesting lesson in hardware abstraction.

The Larson scanner, named after famed TV producer Glen A. Larson for his penchant for incorporating it into shows like Battlestar Galactica and Knight Rider, is actually hard to execute in hardware thanks to the fading tail that follows the lead pixel as it dances back and forth across the display. [Eric Gunnerson] decided to make this and other animation effects easier to achieve with Fade, a custom framework for LED animations that runs on an ESP32.

LED animations are fine, but what about servos? Could Fade be modified to support them? This turned out to be a fairly easy mod thanks to Fade’s architecture and [Eric]’s existing support for non-addressable LEDs via PWM signals. And it was even possible to support more than the 16 PWM channels on an ESP32by adding a UDP connection that puts multiple ESP32s under the control of a central microcontroller.

The video below shows [Eric]’s demo of servo support, with an eight-channel electromechanical Larson scanner. Each “pixel” is a painted ping pong ball swinging back and forth on a hobby servo, and the whole thing sounds just about as awful as you’d expect it to. If you squint just right, the effect looks pretty convincing, but that’s hardly the point. The real story here is [Eric]’s thoughtful architecture, which made the mods easier than starting from scratch.

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Sticker Brings The Heat

February 13, 2022 by 17 Comments

[Carl] is always looking at making heater plates for PCB reflow and other applications. In his latest video, he shows how he is using thin flexible PCBs with adhesive backs as stickers that get hot. You can find gerber files and design files on GitHub.

You might think that this is a pretty simple thing to do with a flex PCB, but it turns out while the PCB might be flexible, the traces aren’t and so the typical long traces you see in a heater won’t allow the sticker to bend, which is a problem if you want to wrap it around, say, a coffee mug.

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Epoxy Resin Night Light Is An Amazing Ocean-Themed Build

February 12, 2022 by 17 Comments

We’ve all seen those “river” tables where a lovely old piece of tree is filled with some blue resin to create a water-like aesthetic. This project from [smartyleowl] takes that basic idea, but pushes it further, and the result is a beautiful build that is as much a diorama as it is a simple lamp.

First up, an appropriate rough piece of unprepared wood is chosen to create a cliff for the underwater scene. Speckles of UV-reactive blue powder are scattered on to the wood and some little plastic coral and marine plants are stuck down as well. A mold is then constructed around the wood using acrylic. Small whale and diver figurines are dangled in place, and blue resin poured in to complete the underwater scene. Once the resin has hardened, it’s polished to a clear sheen and its edges are nicely beveled. It’s then placed on a illuminated base which lights the scene from below, giving it a somewhat ethereal underwater quality.

It’s not a complicated project by any means, but it’s a great example of the beautiful things one can create with the creative application of colored resin. Producing a lamp that looks this good obviously takes some skill, of course – getting a bubble-free resin pour and a nice shiny finish on the wood isn’t easy. However, there’s no reason you can’t start learning today! Video after the break.

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A Most Unconventional Lego Walker

February 11, 2022 by 15 Comments

Lego Technic is a wonderful thing, making it easy to toy around with all manner of complicated mechanical assemblies without needing to do any difficult fabrication. [touthomme] recently posted one such creation to Reddit – a walker design that is rather unconventional.

The design dispenses with individually-actuated legs entirely. Instead, the two front legs are joined by an axle which pivots the legs about the body, which is shaped like an oval track. The rear legs are the same. A motorized carriage then travels along the oval track. When the weighted carriage reaches the front of the oval track, it forces the body to tip forwards, pivoting around the front legs and flipping the entire body over, swinging the rear legs forwards to become the front. The cycle then repeats again.

The flipping design, inspired by a toy, is something you wouldn’t expect to see in nature, as few to no animals have evolved mechanisms capable of continual rotation like this. It’s also unlikely to be a particularly efficient way of getting around, and the design would certainly struggle to climb stairs.

Some may claim the method of locomotion is useless, but we don’t like to limit our imaginations in that way. If you can think of a situation in which this walker design would be ideal, let us know in the comments. Alternatively, consider other walking designs for your own builds.  Video after the break.

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Breakbeats Courtesy Of The RP2040

February 9, 2022 by 6 Comments

While one often listens to songs or albums in full, sometimes you just want to lay down a simple beat. [todbot]’s latest project promises to do just that.

The build relies on a Raspberry Pi Pico or any other RP2040-based microcontroller board, and is programmed in CircuitPython. The PWM feature is used for audio output, and it’s loaded with different WAV samples of the classic “Amen” break.

Each measure, a random new sample is chosen and played, changing the beat. Even better, all the samples can loop, and they come in varying lengths, allowing them to overlap and lay over each other to add further depth to the mix. It’s a cinch to setup, as CircuitPython has an AudioMixer object built in.

Those wishing to tinker for themselves can find all the code and samples on Github. A build like this one is a great way to start learning about working with audio and music, after all. We’ve seen [todbot]’s work here before, too. Video after the break.

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Mystery Effect Causing LEDs To Glow During Reflow

February 9, 2022 by 34 Comments

Sometimes you notice something small that nevertheless you can’t explain. [Greg Davill] found himself in just such a situation this week when he noticed some green LEDs glowing dimly when reflowing some boards. Naturally, [Greg] set out to investigate.

The green LEDs were wired up as power indicators, and [Greg] suspected that the polymer caps on the board might be generating a small current somehow that was causing the LEDs to light up ever so slightly. A simple test hooked a polymer cap directly up to a multimeter. When warmed with a heat gun, the meter showed a small current “in the 5-10 uA range.”

Going further, [Greg] soldered an LED to the cap and once again heated it up, this time to 100° C. The LED  glowed, continuing to do so for around 60 seconds with heat removed. The mystery also grew deeper – [Greg] noticed that this only happened with “fresh” capacitors. Once they’d been through one heat cycle, the caps would no longer light an LED when warmed up.

It’s a curious case, and has many speculating as to the causative mechanism on Twitter. Explanations from thermoelectric effects to chemical reactions inside the capacitor. If you’ve got the inside scoop on what’s going on here, don’t hesitate to let us know in the comments. Meanwhile, check out some of [Greg]’s best work – a glowing D20 dice featuring a whopping 2400 LEDs.

[Thanks to J Peterson for the tip!]

3D Printed Circular Prototype Performance Prop Captivates Circus Spectators

February 2, 2022 by 12 Comments

When mathematically inspired maker [Henry Segerman] conspired with circus performer and acrobat [Marcus Paoletti] to advance the craft of acrobatics in round metal objects (such as cyr wheels and German Wheels), they came up with a fascinating concept that has taken shape in what [Henry] calls the Tao-Line.

Similar performance devices go in a straight line or can be turned on edge, but the Tao-Line is far more nimble. This is because the Tao-Line is not a continuous cylinder, but rather is made up of numerous circular shapes that allow the Tao-Line to be turned and inverted at different points in its rotation.

While a circus prop might not be your average Hackaday fare, it’s noteworthy because the Tao-Line started off as a 3D printed prototype, which was then turned into the metal fabrication you see in the video below the break.  It’s an excellent example of how modeling complex shapes as a physical product- not just a 3D model on the screen- can be helpful in the overall design and construction of the full scale piece.

If you’re looking to build something that’s under the big top but not quite so over the top, you might enjoy this mixed-media digital clock. Thanks to [Keith] for the great tip. Be sure to submit send your cool finds via the Tip Line!

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