Light Up Earrings

light up earrings

Unfortunately [ch00f's] been too busy to write for Hack a Day lately, but he has finished off an awesome little project — Christmas LED earrings!

As with all his projects, there is a brilliant write up that covers everything — even for the stuff that didn’t work. But what we really have to admire about this project in particular is the scale at which he was working. The tiny battery squished in between the two boards? A mere 19mAh. Which is actually enough to power the earrings for a few hours, but is only the size and thickness of a few microSD cards!

The second thing that really popped out at us was the boards themselves, there’s just no room for a programming header! To work around this [ch00f] actually made the PCBs in 3 segments, programmed it, and then cut off the programming header section! If that’s not enough ingenuity, how about this – He also included hall effect sensors on-board to turn them off while charging! Not to mention an intricate wood box to charge them in…

Stick around after the break to see the great demo video, it even has some classy music from the 1930′s which really sets the mood.

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Hackaday Staff Update


It’s been just over three weeks since Supply Frame bought Hackaday and a lot has been going on. Almost all of it has been behind the scenes as we make our way through the scaffolding that was built up over the years to run the site. I’ll share more on that as things develop. But now I’d like to introduce you to the staff.

We’ve actually had a staff page for about a year but I’m not sure it was ever announced. Check out the Staff roll call to see a picture and bio of each of our team members. [Brian Benchoff] and I make up the editorial team. [Eric Evenchick] joins us once again as a writer. And over the last couple of weeks we hired [Mathieu Stephan] (aka Limpkin), [Josh Marsh], and [Michael Ciuffo] (aka ch00f). The six of us come from a wide range of backgrounds. We have interests and skill sets that complement each other, and as we get used to working as a team this will equate to better features and more original content. Please join me in welcoming the new writers, and long live Hackaday!


Ghostly images captured only on camera

is that a logo

A while back our good buddy [Ch00f] built a QR code clock, unreadable to both humans and computers. A human couldn’t read the clock because of the digital nature of a QR code, and because the clock used persistence of vision in driving the LEDs, a digital camera can’t capture all the pixels in the QR code at the same time. It’s a highly useless but impressive art piece. Now, [Ch00f] is turning that build on its head. He created a rudimentary display that is invisible to the human eye, but easily detected with a digital camera.

This build exploits a basic property of CMOS digital cameras – the rolling shutter. Because it takes time to get pixels off a modern digital image sensor, each picture is actual a composite of many different strips, each taken slightly out of sequence. You can see this for yourself by taking a picture of something rotating very fast with your camera phone; a picture of an airplane propeller will make the blades appear curved, or look like [Dr. Seuss] has an aeronautical engineering degree.

To create his display, [Ch00f] found a few inexpensive fiber optic lights. By aligning a few of these into columns and lighting them up in a precise sequence, he can exploit the rolling shutter and make an image appear. To the human eye, it looks like a solid wall of illuminated fiber optics.

As for how practical this build is, [Ch00f] says not much. For cell phone cameras, you’d need to have a very, very short exposure time for this to work. The only way to do that is to make this display unbelievably bright, or just put it out in the sun. We can’t see that being practical for any potential use case, but we’d be more than happy to see a large-scale attempt at displaying images with this technique.

LCD-based QR clock


Here’s a new take on the QR clock concept that uses an LCD display. The concept comes from the work [ch00f] put into his two versions of a QR clock (both of which used LED arrays). The time of day is encoded using the Quick Response Code standard. This version generates a new code each second which encapsulates date, hour, minute, and second information. If you look at the image on the left you’ll notice the code is not centered. Take a look at the video after the break and you’ll see that’s because it’s bouncing around the LCD like a screensaver. Watch a little longer and you’ll see the psychedelic effects shown in the image on the right.

A PIC32 is driving the display. It’s connected to a DCF77 radio module which feeds the system atomic clock data. The color plasma effects are used to show when the device has locked onto the radio signal.

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Making a QR clock bigger, cheaper, and better


With the massive response and blog cred from his QR Code clock, [ch00f] felt it was time to step up his game and update his design to a proper commercial product. His new QR clock is bigger, brighter, cheaper, and in every way better than the old version, but these improvements came at a cost.

The LED matrices [ch00f] used in his earlier, smaller version weren’t very aesthetically pleasing. He wanted the lights to shine a brilliant white, and also be somewhat attractive when not illuminated. The 8×8 LED arrays [ch00f] picked up from Futurlec had a disgusting yellow coating on each LED that turned light emitted by the blue LEDs inside to a brilliant white. This simply wouldn’t do for a commercial product with [ch00f]‘s name on it, so he turned to the one place in the universe where everything was for sale:

After some trials and tribulations with component manufacturers in China, [ch00f] had the perfect LED matrix; not too expensive, very good quality control, and something that looked really good when both unpowered and illuminated.

Now that his boards are being spun up, [ch00f] hopes to sell his QR clock on Tindie. Each 24×24 LED matrix should cost less than $100, a pretty good deal if you ask us. He’d like to know if anyone out there has any feature requests, to which we can only say he should get rid of the PCB border. Tiling a few of these displays and controlling them via serial would be much cooler than a QR Code clock.

Months of failure lead up to this EL panel dimmer that pulses to the music


Way back in March [Ch00f] took on a for-hire project to make a suit that lights up to the music. He decided to build something based around a pulsating EL panel. He’s put a lot of time and tried of a few different techniques, but he finally has a working EL panel dimmer.

This is a saga we’ve kept our eye on. The fall seems to have been good to him, after a failure using TRIACS he managed to adjust the brightness of some EL wire by messing with the current going to the driver’s oscillator. Standing on the shoulders of that success he designed the board seen above by getting serious about audio signal processing. There’s a microphone on the board which picks up sound which is then processed into a signal responsible for the brightness of the EL panel.

There’s a demo video after the break, but you’ll want to dig into his article to get all the gritty details.

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POV wheels for a longboard

If you don’t mind working with really small components this POV wheel project for a longboard will certainly attract some attention.

The name of the game here is small and cheap. Small because the wheels are only 72mm in diameter (about 2.8 inches). Cheap because [Ch00f] wants to produce and sell them locally. He went with an ATtiny24 microcontroller driving fifteen LEDs. Obviously this will present a problem as the uC uses a 14-pin SOIC package and that’s just not enough I/O to drive the LEDs individually. Add to that the issue of storing patterns to be displayed and you start to run out of program memory very quickly.

But obvious he pulled it off. The image above shows the wheel displaying the CT logo (for and there are several other patterns shown off in the clip after the break. The LEDs are multiplexed, but the wheel spins fast enough that this turns out to be okay. The rotation is measured by an IR reflectance sensor aimed at the stationary axle. A CR2032 powers the device, with some counterweights added to keep the wheel balanced.

Our only concern is the fragility of the exposed electronics. But if you hit the right BOM price we guess you can just replace the board as needed.

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