The beautiful workmanship in [Andrew]’s LED tree is gorgeous all on its own, but of course there’s more going on than meets the eye. This LED tree can be blown out like a candle and it even playfully challenges a user to blow out all the lights at once in a single breath.
Some of you may remember the fascinating example of an LED you can blow out like a candle which had the trick of using the LED itself as a sensor. Like any diode, the voltage drop across the LED changes very slightly based on temperature. By minimizing thermal mass with surface-mount LEDs and whisker-thin wires, it was possible to detect when the LED was being blown on.
The LED tree shown here uses the same basic principle, but with a few important changes. The electronics have been redesigned and improved, and the Arduino used in the original proof of concept is ditched for stacked custom PCBs. Each board has a diameter under 100 mm in order to take advantage of the fab house’s lower cost for small boards. [Andrew] says that while the boards required a lot of time-consuming hand soldering and assembly, the payoff was that five boards rang in at barely five dollars (plus shipping) and that’s hard to beat.
Watch the tree in action in the brief video embedded below.
[Mile] put together this stunning LED matrix watch, on which the stars of this show are the 256 monochrome 0603 LEDs arranged in a grid on its face. The matrix is only 1.4in in the diagonal and is driven by a combination of an LED driver and some shift registers. The brain is an ATmega328p. We appreciate the extra effort taken to add a USB to UART adapter so the mega can be programmed over USB. It also contains all the necessary circuitry to charge and maintain the lithium battery inside safely.
Input into the device is done with a hall effect sensor which keeps the build from having any moving parts. The body is a combination of 3D printed parts and really fetching brass details connecting to the band.
If it weren’t over the top enough the build even has an ambient light sensor so the display can dim or brighten depending. We bet [Mile] is pretty proud to wear this on their wrist.
For Game of Thrones fans, it’s an awkward time. The show has ended its run on HBO (not without a certain level of controversy), the planned prequel is still years away, and who knows when George R. R. Martin will actually get around to writing the final books in the series. Fans have no choice but to entertain themselves while waiting for further tales of adventure from Westeros, which is how we get things like this motorized clock from [Techarge].
Inspired by the now iconic opening sequence from the HBO series, elements of the 3D printed model spin around while the theme song is played courtesy of a DFPlayer Mini MP3 player module and small 2 watt speaker. The audio hardware, motor, and four digit LED display module in the front are all connected to an Arduino with a custom PCB shield, giving the inside of the clock a very clean and professional appearance.
Around the back side [Techarge] has two small push buttons to set the hour and minutes, and a large toggle to control the music and movement. As of right now it needs to be switched on and off manually, but a future enhancement could see it kick on hourly. We’d also like to see an RTC module added to the PCB, or better yet, switch over to the ESP8266 and just pull the time down from NTP.
Who knows? By the time you’ve built one of these clocks for yourself, and the hand-made Iron Throne phone charger stand to go with it, maybe ol’ George will have slipped out a new book. But don’t count on it.
An important distinction between equipment used for caving, climbing, biking, and other outdoor activities is the level of stress that’s generally applied. For instance, while climbing helmets are built to withstand the impact of sharp rocks, they’re not made to protect a biker’s head from suddenly hitting the ground. Likewise, while camping headlamps may be able to survive a light rainfall, they’re probably not made to shine at the 800 lumens after being submerged underwater.
[LukeM] built himself a caving headlight, after being “fed up with what was available on the market”. While his project is a bit older, it’s still pretty helpful for any newer hobbyists looking to try their hand at building a custom headlamp. Many cavers have to carry around a few primary – one main light for general visibility and a secondary light for focusing on specific objects. These are typically worn on the helmet, attached somehow to prevent the light source from falling off mid-climb. From tricky operations, varying distances, cost, and ease of battery replacement, there are a number of reasons why a caver might want to build their own customizable head lamp.
The result is rugged, waterproof, reliable, bright enough to supplement flashes in caving photos and also dim enough for general use (30-700 lumens). It has options for wide and narrow beams, displays a neutral to warm color, and is relatively upgradeable without too much trouble. At the same time, it’s also fairly compact, with all of the components packed inside of a short section of 3″x2″ aluminum tubing, protected at the back and front by aluminum and acrylic backings. The LEDs used are four Cree XP-E R2 bin LEDs and a hipFlex driver from TaskLED with programmable settings for max output, thermal protection temperature, warning voltage, and lighting modes. I’m personally already smitten with the level of customizability of this build.
On top of all of that, it’s been cave tested and approved!
Stained glass is an art form that goes back many centuries, with the churches and cathedrals of Europe boasting many stunning examples from the mediaeval masters of the craft. You do not however have to go to York or Chartres cathedrals to experience stained glass, for it remains a vibrant and creative discipline with many contemporary practitioners. One thing the stained glass of today has in common with that of yesteryear though is that it remains static, being composed of pieces of glass held together by metal strips. This is something that [Frank Zhao] has addressed as he has evolved a technique that allows him to incorporate LEDs into static stained glass, making for a particularly eye-catching effect.
It’s likely that we join many readers in not knowing the intricacies of making a piece of stained glass, so his is a fascinating write-up for its step-by-step run-through. His stained glass cat has pieces of glass edged with copper tape, which he then solders together. Driving the LEDs is not something that should be alien to us, but his method of using the copper-and-solder stained glass joints as conductors for them by creating strategically placed cuts is very effective. The final effect is of a homogeneous piece without the cuts being particularly visible , but with a pleasing array of lights on the cat’s tail. Those of us for whom stained glass production is new have learned something of the technique, and stained glass artists have seen their craft do something completely new.
Stained glass hasn’t featured here too often, the closest we’ve come is this striking fake stained glass Iron-Man themed panel a few years ago.
PixMob units are wearable LED devices intended for crowds of attendees at events like concerts. These devices allow synchronized LED effects throughout the crowd. [yeokm1] did a teardown of one obtained from a preview for the 2019 Singapore National Day Parade (NDP), and in the process learned about the devices and their infrastructure.
Suspected IR emitter for the PixMob units, mounted on a lighting tower (marked here in white).
PixMob hardware has been known to change over time. This version has two RGB LEDs (an earlier version had only one), an unmarked EEPROM, an unmarked microcontroller (suspected to be the Abov MC81F4104), and an IR receiver module. Two CR1632 coin cells in series power the device. [yeokm1] has made the schematic and other source files available on the teardown’s GitHub repository for anyone interested in a closer look.
One interesting thing that [yeokm1] discovered during the event was the apparent source of the infrared emitter controlling the devices. Knowing what to look for and reasoning that such an emitter would be mounted with a good view of the crowd, [yeokm1] suspected that the IR transmitter was mounted on a lighting tower. Viewing the tower through a smartphone’s camera revealed a purplish glow not visible to the naked eye, which is exactly the way one would expect an IR emitter to look.
Sadly, there wasn’t any opportunity to record or otherwise analyze the IR signals for later analysis but it’s possible that the IR protocol might be made public at some point. After all, running custom code on an earlier PixMob board was made possible in part by asking the right people for help.
Driving an LED and making it flash is probably the first project that most people will have attempted when learning about microprocessor control of hardware. The Arduino and similar boards have an LED fitted, and turning it on and off is a simple introduction to code. So it’s fair to say that many of us will think we have a pretty good handle on driving an LED; connect it to a I/O pin via a resistor and that’s it. If this describes you, then Mike Harrison’s talk at the recent Hackaday Superconference (embedded below) will be an education.
Mike has appeared on these pages multiple times as he pushes LEDs and PCB techniques to their limits, even designing our 2017 Superconference badge, and his many years of work in the upper echelons of professional LED installations have given him an unrivaled expertise. He has built gigantic art projects for airports, museums, and cities. A talk billed as covering everything he’s learned about LEDs them promises to be a special one.
If there’s a surprise in the talk, it’s that he’s talking very little about LEDs themselves. Instead we’re treated to a fundamental primer in how to drive a lot of LEDs, how to do so efficiently, with good brightness and colour resolution, and without falling into design traps. It’s obvious that some of his advice such at that of relying on DIP switches rather than software for configuration of multi-part installations has been learned the hard way.
Multiple LEDs at once from your driver chip, using a higher voltage.
We are taken through a bit of the background to perceived intensity and gamma correction for the human eyesight. This segues neatly into the question of resolution, for brightness transitions to appear smooth it is necessary to have at least 12 bits, and to deliver that he reaches into his store of microcontroller and driver tips for how to generate PWM at the right bitrate. His favoured driver chip is the Texas TLC5971, so we’re treated to a primer on its operation. A useful tip is to use multiple smaller LEDs rather than a single big one in the quest for brightness, and he shows us how he drives series chains of LEDs from a higher voltage using just the TI chip.
Given the content of the talk this shouldn’t come as a shock, but at the end he reminds us that he doesn’t use all-in-one addressable LEDs such as the WS2932 or APA102. These are the staple of so many projects, but as he points out they are designed for toy type applications and lack the required reliability for a multi-thousand LED install.
Conference talks come in many forms and are always fascinating to hear, but it’s rare to see one that covers such a wide topic from a position of experience. He should write it into a book, we’d buy it!
Some of you may remember the fascinating example of an LED you can blow out like a candle which had the trick of using the LED itself as a sensor. Like any diode, the voltage drop across the LED changes very slightly based on temperature. By minimizing thermal mass with surface-mount LEDs and whisker-thin wires, it was possible to detect when the LED was being blown on.
