Magic Pyramids Blink Eternal With The Power Of The Sun

May 16, 2021 by Kerry Scharfglass 21 Comments

Without knowing it, we’ve spent years watching [Jasper Sikken] piece together an empire of energy harvesting equipment, and now he’s putting the pieces together into wonderful creations. His recently finished solar harvesting pyramids are mesmerizing objects of geometric perfection we’d love to see glinting in the sun.

These solar harvesting pyramids are well described by their name. Each one contains a PCBA around 30mm on a side with a solar energy harvester built around the dedicated AEM10941 IC, a single solar cell, and a very bright green LED. [Jasper] calculates that the solar cell will charge the super capacitor at 20uA at with just 200 lux of light (a level typical for casual indoor spaces) letting it run indefinitely when placed indoors. Amazingly with the LED blinking for 15ms every 2 seconds it will run for 21 days in complete darkness. And that’s it! This is a software-free piece of hardware which requires no input besides dim light and blinks an LED indefinitely.

What about that super capacitor? It’s called a Lithium Ion Capacitor (LIC) and is a hybrid between a typical rechargeable lithium battery and an electrolytic capacitor, offering extremely high capacity in a convenient two leg through hole form factor. This one is a whopping 30 Farad at 3.8 V, and we first saw it when [Jasper] won the Hackaday Earth Day contest last month. Check out that link if you want to know more about their uses and how to integrate them.

For more detail about all of the components of the solar pyramid we need only turn to the Hackaday archives. In December 2019 [Tom Nardi] wrote about building a cheap degassing system for making some very familiar looking resin pyramids. And before that [Donald Papp] brought us another familiar piece of the pyramid when he wrote up a different 1″ x 1″ solar harvesting system that [Jasper] designed.

Check out the video after the break to see what one of these gems looks like from all sides. And for many more experiments leading up the final pyramid check out the logs on the Hackaday.io page.

Continue reading “Magic Pyramids Blink Eternal With The Power Of The Sun” →

8-Bit Computer Addresses LEDs

April 19, 2021 by Bryan Cockfield 2 Comments

Homebrew 8-bit computers tend to have fairly limited displays, often one or more seven-segment displays and an array of LEDs to show the values of RAM or perhaps some other states of the computer. [Duncan] is in the process of building just such an computer, but wondered if there was a way to create a more visually appealing display while still keeping the computer true to its 8-bit roots. With some interesting TTL logic he was able to create this addressable RGB LED display to some remarkable results.

The array works by controlling the WS2812B LED strips with a specific timing cycle which was pioneered by [Tim] for a different project. [Tim] was able to perform this timing cycle with some simple Assembly code, which means that [Duncan] could convert that code into TTL gate logic relatively easily. Using 74LS02 NOR chips gets the job done as far as timing goes, and the pulses are then fed into a shift register and support logic which then creates the signal for the LED strips.

When everything is said and done, [Duncan] has a fully addressable 16×16 RGB LED array as a display for his 8-bit computer without violating any of his design principles and keeping everything to discrete TTL logic chips and a stick of RAM. It’s a unique method of display that might go along really well with any other homebrew computer like this one that’s also built with 74LS chips.

A HALO Of LEDs For Every Ear

April 17, 2021 by Kerry Scharfglass 28 Comments

Few things get a Hackaday staffer excited like bunches of tiny LEDs. The smaller and denser the better, any form will do as long as we can get a macro shot or a video of a buttery smooth animation. This time we turn to [Sawaiz Syed] and [Open Kolibri] to deliver the brightly lit goods with the minuscule HALO 90 reactive LED earrings.

The HALO 90’s are designed to work as earrings, though we suspect they’d make equally great brooches, hair accessories, or desk objects. To fit this purpose each one is a minuscule 24 mm in diameter and weighs a featherweight 5.2 grams with the CR2032 battery (2.1 g for the PCBA alone). Functionally their current software includes three animation modes, each selectable via a button on device; audio reactive, halo (fully lit), and sparkle. Check out the documentation for details on expected battery life in each mode, but suffice to say that no matter what these earrings will make it through a few nights out.

In terms of hardware, the HALO 90’s are as straightforward as you’d expect. Each device is driven by an STM8 at its maximum 16MHz which is more than fast enough to keep the 90 charliplexed 0402 LEDs humming along at a 1kHz update rate, even with realtime audio processing. In fact the BOM here is refreshingly simple with just 8 components; the LEDs, microcontroller and microphone, battery holder and passives, and the button. [Sawaiz] even designed an exceptionally slick case to go with each pair of earrings, which holds two HALO 90’s with two CR2032’s and includes a magnetic closure for the most satisfying lid action possible.

As with some of his other work, [Sawaiz] has produced a wealth of exceptional documentation to go with the HALO 90’s. They’re available straight from him fully assembled, but with documentation this good the path to a home build should be well lit and accessible. He’s even chosen parts with an eye towards long availability, low cost, and ease of sourcing so no matter when you decide to get started it should be a snap.

It was difficult to choose just a few images from [Sawaiz]’s mesmerizing collection, so if you need more feast your eyes on the expanded set after the break.

Continue reading “A HALO Of LEDs For Every Ear” →

LED Brightness Adjustment Uses Itself As Sensor

April 11, 2021 by Donald Papp 16 Comments

This is a story about a successful system that nevertheless failed to make the cut. An experimental LED brightness adjustment is something [Mitxela] explored in a project for a high-precision clock; one that shows time down to the nearest millisecond, and won’t flicker or otherwise look weird when photographed with a high-speed camera. To pull this off means reinventing many things about a clock display, including how to handle brightness adjustment elegantly. Now, to be clear, the brightness adjustment idea described here is something that did not end up being used, but it’s interesting enough that [Mitxela] wrote it up and we’re very glad he did.

The idea was to have a smooth and seamless automatic brightness adjustment, ideally with no added components. Since LEDs can be used as light sensors, [Mitxela] saw an opportunity to use elements of the clock displays themselves as sensors. This is how it works: a charge in the p-n junction that makes up an LED will decay at a rate proportional to the amount of light hitting the junction. By measuring the speed of this decay, it’s therefore possible to tell how much light is hitting the LED. It’s effective and elegant, but there are a few practical issues to deal with.

The first failed idea was to employ as sensors the unused decimal points in the seven-segment LED modules, but that turned out to have issues. One was the common-cathode wiring of the display modules; this makes them very convenient to drive as displays, but made using the decimal point as a light sensor impractical. The other issue was that the built-in diffuser that makes the displays easier to read absorbs a lot of ambient light. A much better option was to use the LEDs in the colon separators between digits, since they’re independent. Naturally they still have to light up in addition to being used as sensors, but [Mitxela] made a successful prototype by performing the necessary measurements in between the LEDs being driven by PWM.

Despite how clever and efficient the solution was, in the end what sank it was the fact that the LEDs just don’t do a very good job of sensing ambient light for this purpose. The LEDs are simply too directional. Even after sanding away the top (lens) part of the LEDs, they still had a very narrow field of view. As [Mitxela] describes it, tilting the clock towards the ceiling could send it to full brightness, and the shadow of one’s head falling across the clock would plummet it into “night mode” dimness. In short, it responded to what was directly in front of it, rather than the ambient light level as a whole.

It’s a reminder that sometimes a solution simply won’t tick all the right boxes, and it can happen for unexpected reasons. Still, LEDs are versatile things. Not only can they sense light, but as the name implies they’re also diodes. As diodes can be used as temperature sensors that means LEDs can as well.

This Vintage LED Matrix Lives In A Gold Bathtub

April 3, 2021 by Donald Papp 9 Comments

Early LED displays came in all sorts of configurations. Because the LED was fairly new technology, all kinds of ideas were getting tried, and with all that work there was plenty of opportunity for hardware that didn’t make the cut to fall into obscurity. That’s exactly what happened to the Hewlett-Packard 5082-7002, a 5×7 LED matrix display with something many of its brethren didn’t: an oversized gold tub to sit in.

It doesn’t seem that these displays were ever used in any actual products, and its origins are a mystery, but the device itself was nevertheless assigned an HP part number. Beyond that, not much is known about them, but [Industrial Alchemy] reminds us that many early LED devices were poorly documented and never produced in any real quantities. They became forgotten hardware, waiting to be rediscovered.

The 5082-7002 has a oversized gold tub that makes the 5×7 LED matrix mounted inside look puny by comparison, and reading any display made from these units would be difficult because the large size of the device would mean a lot of empty space between each character or digit. But it’s definitely got a striking look to it, no doubt about that.

What’s neat is that the 5802-7002 actually showed up in a video we featured with a look back at cool old LED technology. If you would like to (briefly) see the HP 5802-7002 a bit closer under a microscope, here is a link to the video, cued to 2:19.

Over-Engineered Incandescent Numerical Display Shows Great Workmanship

April 1, 2021 by Donald Papp 18 Comments

Back before LED technology came into its own, displays used incandescent bulbs. These vintage incandescent displays weren’t necessarily big; the Eaton 925H-C fiber optic display, for example, has numbers barely 7 mm tall and packs two of them into a tiny area. Of course, the depth of the display module itself is huge by today’s standards; those components have got to go somewhere, after all.

This particular device is, in [Industrial Alchemy]’s words, “[d]ripping with the spending excess that only a bottomless military budget can provide… the Eaton 925H-C may not be a practical device, but it is certainly an impressive one.”

The way the display works is this: individual incandescent bulbs light up fiber optic light guides, which terminate on the face of the display in small dots to make up a numerical display. With only fourteen bulbs, the dots we see here clearly aren’t individually addressable; the two digits are most likely broken up into seven segments each, with three dots making up each segment.

No expense seems spared in the design and manufacture of these displays. Even the incandescent lamps have individual shock absorbers.

The sheer amount of workmanship in these displays is remarkable, and their design makes them easy to retrofit with LED technology instead of replacing the tiny incandescent lamps. In a stark contrast to all of the machined aluminum and gold plated contacts seen here in the Eaton 925H-C, take a look at this Soviet-era seven-segment incandescent display whose construction is far less sophisticated, but shows off its own clever engineering. We’ve also seen more modern DIY takes on the concept, using LED light sources and cured UV resin light pipes to get that vintage look to the displays.

Building An LED Etch-A-Sketch

March 11, 2021 by Lewin Day 14 Comments

The Etch-A-Sketch was a toy that demanded mastery. Some grew capable of creating masterful artworks, while others struggled to do more than a jumbled mess of angry, angular lines. The inherent limitations of being able to only draw a singular, connected line are all part of the fun, of course, and [gatoninja236] recreated that in a modern, LED form.

The build uses a Raspberry Pi to run the show, with a 64×64 LED matrix hooked up to the GPIO pins serving as a display. Two encoders are used to recreate the famous Etch-A-Sketch interface, hooked up to an Arduino Nano that then communicates encoder data to the Pi over I2C, due to the limited GPIOs available. There’s also an MPU6050 accelerometer board, used to enable the intuitive shake-to-clear functionality.

The final result is a fun LED toy that, unlike a real Etch-A-Sketch, you can play in the dark. We’ve seen other sneaky hacks on the classic toy before, too – like this Samsung TV cleverly hidden in a lookalike shell. Video after the break. Continue reading “Building An LED Etch-A-Sketch” →