Clock-of-Clocks Adds Light-Pipe Hands For Beauty And Function

We’ve gotten used to seeing “meta clocks,” clocks that use an array of analog clock faces and piece together characters using the hands of the clocks. They’re very clever, and we always like to see them, especially when they come with detailed build instructions like this one does.

What’s also nice about [Erich Styger]’s “MetaClockClock” display is the twist on the original concept. Where most clock-of-clocks depend on the contrast between the hands and the faces of the analog movements, [Erich] added light to the mix. Hidden inside the bezel of each clock is a strip of RGB LEDs; coupled with the clear acrylic hands of the clock, which act as light pipes, each clock can contribute different shapes of different colors to the display. Each clock is built around a dual-shaft stepper motor of the kind used in car dashboard gauges; the motors each live on a custom PCB, while the LEDs are mounted on a ring-shaped PCB of their own. Twenty-four of the clocks are mounted in a very nice walnut panel, which works really well with the light-pipe hands. The video below shows just some of the display possibilities.

[Erich] has documented his build process in extreme detail, and has all the design files up on GitHub. We won’t say that recreating his build will be easy — there are a lot of skills needed here, from electronics to woodworking — but at least all the information is there. We think this is a beautiful upgrade to [Erich]’s earlier version, and we’d love to see more of these built.

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Inputs Of Interest: Marsback M1 Is A Portable Party Peripheral

Again, let’s just get this out of the way up front: I got this lovely little 75% keyboard for free from a gaming accessories company called Marsback. It’s a functioning prototype of a keyboard that they have up on Kickstarter as of March 2nd. It comes in three color schemes: dark, white and sakura pink, which is white and pink with cherry blossoms.

This illustration of the lube points is from my email string with Marsback.

Marsback found me through my personal website and contacted me directly to gauge my interest in this keyboard. I’ll admit that I wasn’t too excited about it until I scrolled further in the email and saw that they are producing their own switches in-house.

I think that’s a really interesting choice given that Cherry MX and other switches exist, and there so many Cherry MX clones out there already. Naturally, I had to investigate, so following a short review, I’ll take it apart.

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Dynamic Map Of Italy On A PCB

While most PCBs stick to tried-and-true methods of passing electrons through their layers of carefully-etched copper, modern construction methods allow for a large degree of customization of most aspects of these boards. From solder mask to number of layers, and even the shape of the board itself, everything is open for artistic license and experimentation now. [Luca] shows off some of these features with his PCB which acts as a live map of Italy.

The PCB is cut out in the shape of the famous boot, with an LED strategically placed in each of 20 regions in the country. This turns the PCB into a map with the RGB LEDs having the ability to be programmed to show any data that one might want. It’s powered by a Wemos D1 Mini (based on an ESP8266) which makes programming it straightforward. [Luca] has some sample programs which fetch live data from various sources, with it currently gathering daily COVID infection rates reported for each of the 20 regions.

The ability to turn a seemingly boring way to easily attach electronic parts together into a work of art without needing too much specialized equipment is a fantastic development in PCBs. We’ve seen them turned into full-color art installations with all the mask colors available, too, so the possibilities for interesting-looking (as well as interesting-behaving) circuits are really opening up.

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Running Way More LED Strips On A Raspberry Pi With DMA

The Raspberry Pi is a powerful computer in a compact form factor, making it highly useful for all manner of projects. However, it lacks some of the IO capabilities you might find on a common microcontroller. This is most apparent when it comes to running addressable LED strings. Normally, this is done using the Pi’s PWM or audio output, and is limited to just a couple of short strings. However, [Jeremy P Bentham] has found a way to leverage the Pi’s hardware to overcome these limitations.

The trick is using the Raspberry Pi’s little-documented Secondary Memory Interface. The SMI hardware allows the Pi to shift out data to 8 or 16 I/O pins in parallel using direct memory access (DMA), with fast and accurate timing. This makes it perfect for generating signals such as those used by WS2812B LEDs, also known as NeoPixels.

With [Jeremy]’s code and the right supporting hardware, it’s possible to run up to 16 LED strips of arbitrary length from the Raspberry Pi. [Jeremy] does a great job outlining how it all works, covering everything from the data format used by WS2812B LEDs to the way cache needs to be handled to avoid garbled data. The hack works on all Pis, from the humble Pi Zero to the powerful Pi 4. Thanks to using DMA, the technique doesn’t overload the CPU, so performance should be good across the board.

Of course, there are other ways to drive a ton of LEDs; we’ve seen 20,000 running on an ESP32, for example.

[Thanks to Petiepooo for the tip!]

The Most Expensive D20 You’ll See Today

Roll your negotiation skill, because this d20 is a hefty one. The Tweet is also below. We are charmed by [Greg Davill]’s twenty-sided LED contraption, but what do we call it? Is it a device? A sculpture? A die? Even though “d20” is right on his custom controller PCB, we don’t think this will grace the table at the next elf campaign since it is rather like taking a Rolls Royce to the grocery store. Our builder estimates the price tag at $350 USD and that includes twenty custom PCB light panels with their components, a controller board, one battery pack, and the 3D printed chassis that has to friction-fit the light faces.

Power and communication for all the panels rely on twenty ribbon cables daisy-chained throughout the printed scaffolding, which you can see in the picture above. [Greg] made a six-sided LED cube last year, and there are more details for it, but we suspect he learned his lesson about soldering thousands of lights by hand. There are one-hundred-twenty LEDs per panel, times twenty, that is over two-thousand blinkenlights. We don’t yet have specs on the controller, but last time he used a SAMD51 processor to support over three-thousand lights. We don’t know where he’ll go next, but we’re game if he wants to make a chandelier for Hackaday’s secret underground lair.

(Editor’s Note: If you were at Supercon last year, and you got to play with this thing in the flesh, it’s worth it!)

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Abused Hard Drive Becomes POV Clock

We all know that there’s not much to do with an old hard drive. Once you render the platters unreadable and perhaps harvest those powerful magnets, there’s not much left of interest. Unless, of course, you turn the whole thing into a persistence-of-vision clock.

At least that’s what [Leo] did when he created “PendoLux”. The clock itself is pretty simple; like any POV project, it just requires a way to move an array of flashing LEDs back and forth rapidly enough that they can trick the eye into seeing a solid image. [Leo] put the read head mechanism of an old HDD into use for that, after stripping the platters and motor out of it first.

The voice coil and magnet of the head arm are left intact, while a 3D-printed arm carrying seven RGB LEDs replaces the old heads. [Leo] added a small spring to return the arm to a neutral position, and used an Arduino to drive the coil and flash the LEDs. Getting the timing just right was a matter of trial and error; he also needed to eschew the standard LED libraries because of his heavy use of interrupts and used direct addressing instead.

POV clocks may have dropped out of style lately — this hard drive POV clock and a CD-ROM version were posted years ago. But [Leo]’s clock is pretty good looking even for a work in progress, so maybe the style will be making a comeback.

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Trick From 1903 Makes An Old Monochrome TV Spit Some Colours

Its safe to say that colour television is taken for granted nowadays. Consumed by the modern marketing jargon of colour dynamic range, colour space accuracy and depth, it is easy to overlook the humble beginnings of image reproduction when simply reconstructing an image with the slightest hint of colour required some serious ingenuity and earned you a well deserved pat on the back!

[anfractuosus] revisited an old gem of a technique, first patented in 1903 and used it to successful make an old monochrome TV produce a colour image. The idea in essence, is actually similar to what cheap image sensors and LCDs still use today. Rather than relying on true RGB colour generation by individually integrating colour sources as AMOLED does, we take an easier route: Produce a simpler monochrome image where each colour pixel is physically represented by four monochrome sub-pixels, one for each colour component. Now light up each of the sub-pixels according to the colour information of your image and rely on an external colour filter array to combine and spit out the correct colours.

He first used some image processing to convert a standard colour video into the aforementioned monochrome sub-pixel representation. Next, a Bayer colour filter array was printed on some acetate sheets using an inkjet printer (the original inventors used potato starch!), which when overlaid on top of the monochrome monitor, magically result in colour output.

There are some problems associated with this technique, mainly to do with the difficulty in measuring the size of the TV pixels and then producing and perfectly aligning a filter sheet for it. You should check out how [anfractuosus] went about solving those issues.

So now you know a bit more about colour image generation, but how about colour TV transmission? Check out an earlier piece to learn more.

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