Sound And Light Play Off Acrylic And Wire In This Engaging Circuit Sculpture

February 18, 2022 by Dan Maloney 3 Comments

It’s no secret that we really like circuit sculptures around here, and we never tire of seeing what creative ways people come up with to celebrate the components used to make a project, rather than locking them away in an enclosure. And a circuit sculpture that incorporates sound and light in its design is always a real treat to discover.

Called “cwymriad” by its designer, [Eirik Brandal], this sound sculpture incorporates all kinds of beautiful elements. The framework is made from thick pieces of acrylic, set at interesting angles to each other and in contrasting colors. The sound-generating circuit, which uses square wave outputs from an ESP32 to provide carrier and modulation signals for a dual ring modulator, is built on a framework of tinned wires. The sounds the sculpture makes have a lovely resonance to them, like random bells and chimes that fade and mix together. There’s also a matrix of white LEDs that form a sort of digital oscilloscope that displays shifting waveforms in time with the music.

While we like the way this looks and sounds, the real bonus here is the details of construction in the video below. [Eirik]’s careful craftsmanship working with multiple materials is evident throughout; we were especially impressed by the work needed to drill holes for the LED matrix, any one of which slightly out of place would have been painfully obvious in the finished product.

This is far from [Eirik]’s first appearance on these pages. His vacuum tube and silicon “ioalieia” was featured just a few weeks back, and “ddrysfeöd” used the acrylic parts as light pipes in a lovely way.

Continue reading “Sound And Light Play Off Acrylic And Wire In This Engaging Circuit Sculpture” →

Weird Phosphor Conversion LEDs Found In Cheap LED String

February 16, 2022 by Lewin Day 40 Comments

[Tim] recently found himself tinkering with a cheap string of LEDs. Far from an advanced, IC-controlled addressable set, these were merely a string with LEDs of four colors that could be switched on and off. However, digging in to the LEDs themselves turned up a curious find.

The LEDs were set up in a parallel/anti-parallel fashion. The two power lines ran the length of the string, with all the LEDs installed across them. If polarity was applied in one direction, the red and yellow LEDs would light up, in the other, the blue and green LEDs would light together.

This raised a question for [Tim], as typically, different LEDs light up at different forward voltages and this can cause issues when running different color LEDs in parallel together. What he instead found was that all the LEDs were actually blue LEDs in their fundamental construction. However, the red, yellow, and green LEDs had all been given a phosphor coating. In these devices, when the blue LED underneath lit up, the phosphor converted the light into the desired color. [Tim] was able to confirm this behaviour by illuminating the phosphor manually using an external UV-A LED.

It’s an interesting choice, but it’s certainly one way of making a multicolored string of LEDs. If you wanna get fancier though, consider studying this tutorial on working with addressable LED strings!

[Thanks to J Peterson for the tip!]

This ESP32 Pico Wristwatch Has Plenty Of Potential

February 12, 2022 by Dave Rowntree 12 Comments

First hand-built prototype. Nurse! isopropyl alcohol, stat!

Prolific hacker [Sulfuroid] is a medical doctor by day, and an electronics hobbyist by night, and quite how he finds the time, we have no idea.

The project we want to highlight is an ESP32 based LED smart watch, which we’ll sure you’ll agree, looks pretty nicely developed so far, and [Sulfuroid] has bigger plans, as you may find, when you dig into the GitHub repo. This analog-style design uses four groups of 0603-sized LEDs, arranged circularly to indicate the passage of time, or anything else you fancy. Since there are four control buttons, a pancake vibration motor, as well as Wi-Fi and Bluetooth, the possibilities are endless.

In order to stand a hope of driving those 192 LEDs from a single ESP32-Pico-D4, it was necessary to use a multiplexed LED driver, courtesy of the Lumissil IS31FL3733 device, which can handle arrays up to 12 x 16 devices. This chip is one to remember, since it has some really nice features, such as global current control to reduce CPU overhead, automatic breathing loops for those fancy fade effects, and even includes a handy open/short detection function, so it can report back assembly problems, assisting in reworking your dodgy soldering!

Power and interfacing are taken care of via USB-C, with a TP4054 single Li-Ion cell charger chip handling the battery. This is a Taiwanese clone of the popular LTC4054, but that chip may be a bit hard to get at the moment. There is the common-as-muck CP2104 USB chip dealing with the emulated serial port side of things, since for some reason, the ESP32 still does not support USB. The Pico-D4 does have RTC support, but [Sulfuroid] decided to use a DS3231M RTC chip instead. We noticed the touch functionality wasn’t broken out – that could be added easily in the next revision!

We’ve covered watches a lot, because who doesn’t want custom geek-wear! Here’s a slick one, a fun one with the brains on display, and finally one using charlieplexing to get the component count down.

Tutorial Teaches You To Use Neopixels With Micropython

February 12, 2022 by Lewin Day 4 Comments

Addressable LEDs are wonderful things, with products like Neopixels making it easy to create all kinds of vibrant, blinking glowables. However, for those without a lot of electronics experience, using these devices can seem a bit daunting. [Bhavesh Kakwani] is here to help, with his tutorial on getting started with Neopixels using the MicroPython environment.

The tutorial flows on from [Bhavesh’s] Blink example for MicroPython, and is aimed at beginners who are learning for the first time. It explains the theory behind RGB color mixing that allows one to generate all manner of colors with WS2812B-based LED strings, and how to code for the Raspberry Pi Pico to make these LEDs do one’s bidding.

The guide even covers the use of the Wokwi simulation tool. This is a great way for beginners to test their projects before having to play with actual hardware. This is useful for beginners, because it’s a great way to catch mistakes – is there a software problem, or did they push the soldering iron through the microcontroller? It’s also a technique that pays dividends when working on more complicated projects.

Whether you’re entirely new to the embedded world, or just want to learn the intricacies of talking to addressable LEDs and make sense of color mixing theory, this tutorial will serve you well. Before you know it, you’ll be building glowing projects with the best of them!

DIY Nanoleaf LED Panels Offer Peace Of Mind

February 11, 2022 by Lewin Day 14 Comments

Nanoleaf light panels are a popular product for creating glowing geometric designs on walls. However, for those that like to avoid IoT devices that integrate with big cloud services, they’re not ideal, and involve compromising on one’s privacy, somewhat. [Viktor] decided to build something of his own instead to avoid this problem.

The design is that of an equilateral triangle, which allows the panels to tesselate well. Each panel consists of two 3D printed parts. The black PLA base holds the WS2812B LED strips, cabling, and ESP8266 controller, while a white PLA cover goes over the top, which acts as a diffuser to spread the light from the individual LEDs. Each triangle contains 24 LEDs, and six triangles together consume around 1.6 amps when in use.

The benefit of the system is that it’s not controlled from a company’s cloud system, which can be shutdown at any time. [Viktor’s] setup runs entirely independently, and can be controlled from a simple web page. Plus, there’s nothing stopping him from modifying the code to use the panels for any purpose; commercial products like Nanoleaf don’t offer anywhere near the flexibility of building your own.

We’ve seen others build their own smart lighting with similar techniques before, too. Video after the break.

Continue reading “DIY Nanoleaf LED Panels Offer Peace Of Mind” →

Mystery Effect Causing LEDs To Glow During Reflow

February 9, 2022 by Lewin Day 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!]

Tiny LED Matrix Panels Tile Together Perfectly

January 6, 2022 by Dan Maloney 15 Comments

There’s a lot to admire about LED matrix projects, which more often than not end up looking really cool. But most of them rely on RGB matrix panels sourced from the surplus market, and while there’s nothing wrong with that, building your own tiny, tileable LED matrix panels makes these builds just a little bit cooler.

There’s a lot to admire about these matrix panels, not least of which is the seamless way they tile together. But to get to that point, [sjm4306] had a lot of prep work to do. He started with a much simpler 5×7 array, using the popular WS2812 RGB LEDs on a custom PCB. With a little practice under his belt, it was time to move to the much smaller SK6805 LEDs, which were laid out in an 8×8 matrix. The board layout is about as compact as it can be; [sjm4306] reports that it pushed the PCB fab to their limits, but he ended up with LEDs spaced perfectly on the board and just enough margin to keep consistent spacing in two dimensions when the boards are adjacent to each other.

Assembly of the boards was challenging, to say the least. The video below shows that the design left barely enough room for handling the LEDs with tweezers, and some fancy finagling was needed to get the boards on and off the hotplate for reflow. [sjm4306] says that he’ll be exploring JLC PCB’s assembly service in the future, since each board took an hour for him to assemble. But they look fantastic when daisy-chained together, with no detectable gaps at the joints.

With matrices like these, the possibilities are endless. We’ve even got a whole list of LED matrix projects over on Hackaday.io for you to check out.

Continue reading “Tiny LED Matrix Panels Tile Together Perfectly” →