DIY Button Matrix Lights Up And Speaks I2C

May 17, 2019 by Donald Papp 2 Comments

[David Johnson-Davies] always wanted an illuminated button matrix for projects, but cost was never very friendly. That all changed when he discovered a cheap source of illuminated pushbuttons on Aliexpress, leading to this DIY 4×4 illuminated button matrix design which communicates over I²C. The button states can be read independently of setting the light pattern, and an optional interrupt signal gets pulled low whenever there is a change detected. Not bad for one PCB plus about $10-worth in components!

The device uses every single pin on an ATtiny88, and because each button gets its own pin the keypresses can be detected with pin-change interrupts. The state reporting of buttons over I²C is unambiguous, even when multiple buttons are pressed simultaneously. A simple protocol provides all the needed functionality, and all connections are brought to the board’s edge to allow for easily tiling multiple panels.

The GitHub repository contains the code and PCB files and [David] helpfully shared the board files to OSH Park and PCBWay for easy ordering. In addition, he provides two demos (Tacoyaki and Tacoyaki+) which are games related to the classic Lights Out to show off the matrix.

A Ping Pong Ball LED Video Wall

May 17, 2019 by Dan Maloney 6 Comments

Constrained builds are often the most fun. Throw an artificial limit into the mix, like time limiting your effort or restricting yourself to what’s on hand, and there’s no telling what will happen.

[bitluni] actually chose both of those constraints for this ping pong ball LED video display, and the results are pretty cool, even if the journey was a little rough. It seems like using sheet steel for the support of his 15 x 20 Neopixel display was a mistake, at least in hindsight. A CNC router would probably have made the job of drilling 300 holes quite a bit easier, but when all you have is a hand drill and a time limit, you soldier on. Six strings of Neopixels fill the holes, a largish power supply provides the 18 or so amps needed, and an Arduino knock-off controls the display. The ping pong ball diffusers are a nice touch, even if punching holes in them cost [bitluni] a soldering iron tip or two. The display is shown in action in the video below, mostly with scrolling text. If we may make a modest suggestion, a game of Pong on a ping pong ball display might be fun.

[bitluni] says that the display is on its way to Maker Faire Berlin this weekend, so stop by and say hi. Maybe he’ll have some of his other cool builds too, like his Sony Watchman Game Boy mashup, or the electric scooter of questionable legality.

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An Impeccably Designed High-Speed LED Flash

May 16, 2019 by Tom Nardi 58 Comments

If you want to take a picture of something fast, and we mean really fast, you need to have a suitably rapid flash to illuminate it. A standard camera flash might be good enough to help capture kids running around the back yard at night, but it’s not going to do you much good if you’re trying to get a picture of a bullet shattering a piece of glass. For that you’ll need something that can produce microsecond flashes, allowing you to essentially “freeze” motion.

You can buy a flash that fast, but they aren’t common, and they certainly aren’t cheap. [td0g] thought he could improve on the situation by developing his own microsecond flash, and he was kind enough to not only share it with the world, but create a fantastically detailed write-up that takes us through the entire design and construction process. Even if you aren’t in the market for a hyper-fast flash for your camera, this is a fascinating look at how you can build an extremely specialized piece of gear out of relatively common hardware components.

So what goes into a fast LED flash? Rather unsurprisingly, the build starts with high-quality LEDs. After some research, [td0g] went with an even dozen CREE CXA2530 arrays at just shy of $7 USD each. Not exactly cheap, but luckily the rest of the hardware is pretty garden variety stuff, including a ATMega328P microcontroller, some MOSFETs, and a TC4452 driver. He did pack in some monstrous 400 V 10μf capacitors, but has since realized they were considerably overkill and says he would swap them out if doing it all over again.

To make development easier (and less costly, should anything go wrong), [td0g] designed the flash so that the LEDs are arranged in banks of three which can be easily removed or swapped in the 3D printed case. Each trio of LEDs is in a removable “sled” that also holds the corresponding capacitor and MOSFET. Then it was just a matter of getting the capacitors charged up and safely dumping their energy into the banks of LEDs without frying anything. Simple.

At this point, the astute reader is probably thinking that a high speed flash is worthless without an equally fast way of triggering it. You’d be right, but [td0g] already figured that part. A couple years back we covered his incredible ballistic chronometer which is being used as a sensor to fire off his new flash.

LED Panel Lamp Is A Great Way To Use Protoboard

May 13, 2019 by Lewin Day 9 Comments

It’s now possible to source chip-on-board LED modules that have huge light output in a simple, easy to use package. However they can have major power requirements, and cheaper modules are also susceptible to dead spots. [Heliox] put together a great LED lamp design the old-school way, showing there’s more than one way to get the job done.

Standard SMD LEDs are the order of the day here. The LEDs are laid out on protoboard in neat rows, making them easy to solder in place. This also makes power distribution a cinch, with the copper traces carrying the power to each row. Power is courtesy of 18650 lithium batteries installed in the back of the 3D printed housing. A GoPro-style mount is printed as part of the case, allowing the lamp to be easily mounted in a variety of ways.

It’s a quick, cheap and easy way to build a versatile LED lamp. With a diffuser installed and integrated USB charging, we could see this making an excellent portable device for on-the-go videographers or technicians. We’ve seen [Heliox]’s LED creations before, too. Video after the break.

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LED Jewelry Makes Neat Use Of Brass

May 13, 2019 by Lewin Day 7 Comments

Wearable electronics can be both fun and fashionable. However, there are certain challenges involved in neatly integrating electronic components in a way that is both functional and comfortable for the wearer. In this vein, [Jiri Praus] has managed to create some glowing earrings that are remarkably simple to boot.

The body of the earring also acts as the conductor and battery holder, all in one.

The earrings start out with brass rod, bent with pliers and soldered at the ends. By following a paper template, it’s possible to get neat and accurate bends by hand, which is necessary to make a matching pair. Through careful design, the brass rods are soldered to the LEDs, and more rod is then used to create an integrated holder for a coin cell battery, which powers the lights.

Thanks to [Jiri]’s smart designs — which we’ve featured before in the form of a blooming wireframe tulip — no wires are needed. The brass rods which make up the body of the jewelry also act as the conductors to pass current to the LEDs. The internal resistance of the coin cell battery also eliminates the need for an in-line resistor. In combination, this serves to create a simple and attractive finished product that should shine for several hours.

We’ve seen other LED earring designs before, too. There are plenty of ways to experiment with glowing jewelry, and if you’ve done something novel, be sure to let us know.

Lots Of Blinky! ESP32 Drives 20,000 WS2812 LEDs

May 7, 2019 by Bob Baddeley 17 Comments

20,000 LEDs sounds like an amazing amount of blink. When we start to consider the process of putting together 20,000 of anything, and then controlling them all with a small piece of electronics the size of a postage stamp, we get a little bit dizzy. Continue reading “Lots Of Blinky! ESP32 Drives 20,000 WS2812 LEDs” →

Getting That Neon Sign Look Without All The Hassle

May 6, 2019 by Ted Yapo 27 Comments

We all love the look of neon signage, but the between the glassblowing equipment, gas cylinders, high voltage, and the associated skill set, it’s not practical for everyone. Luckily, these days there’s a good alternative: “neon” flexible LED strips. This is the approach [Benni] recently took in making a large logo display, and the results speak for themselves.

[Benni] sourced the strips from AliExpress. They’re 8 mm wide and can be cut to length in multiples of 4.2 cm. Inside, there are strips of RGB LEDs, making the displays that much more versatile than actual neon. Covering the LEDs is a silicone diffuser strip that completes the illusion of a neon tube. The flexibility of the strips make them easy to bend into different shapes, but also mean a solid substrate of some sort is required to make them hold their shape. In [Benni]’s case, he used a metal frame to which he glued the strips with cyanoacrylate adhesive. He used zip ties to clamp the strips in place while the glue cured, and the fact that he clipped the tails of the zip ties is a testament to his detail-oriented nature; we would probably have left them on. All of the attention payed off though because the end product looks awesome. The finishing touches are supplied by some 3D-printed bezels carrying acrylic diffuser panels and traditional LED strips for the eyes, plus a DMX LED controller.

We’ve seen [Benni]’s work before, like this slick USB rotary encoder peripheral, and like that time, there’s a video which really shows off the project. Have a look, after the jump.

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