Simulated Newton’s Cradle Makes A Flashy Desk Toy

June 1, 2019 by Lewin Day No comments

Newton’s Cradle was once upon a time, a popular desk toy in offices around the world. For [TecnoProfesor], however, it wasn’t quite flashy enough. Instead, they built a simulated version with flashing LEDs. As you do.

Rather than relying on the basic principles of the cradle to make it work, this relies on two servo motors to move the balls on the ends, with the ones in the middle remaining stationary. Each ball is fitted with an RGB LED, which flashes with the simulated “motion” of the cradle. By using ping pong balls, the light from the LEDs is nicely diffused. The frame is built from wooden dowels, metal rods, and acrylic.

It’s a project that is sure to confuse at first glance, but it’s a great way to learn basic microcontroller skills like interfacing with LEDs and servomotors. We’d love to see a version that works like a real Newton’s Cradle, flashing the LEDs as they are hit by their neighbours. We’ve even seen them automated, for the truly lazy among us. Alternatively, one could go completely ridiculous and have such a device tweet on every hit, though you might run afoul of the API’s spam restrictions. If you give it a go, drop us a line.

Make Your Own Old School LED Displays

May 31, 2019 by Lewin Day 13 Comments

We live in an era in which all manner of displays are cheap and readily available. A few dollars spent online can net you a two-line alphanumeric LCD, a graphical OLED screen, or all manner of other options. Years ago however, people made do with little monolithic LED devices. [sjm4306] wanted to recreate something similar, and got down to work (Youtube link, embedded below).

The resulting device uses 0603 sized SMD LEDs, soldered onto a tiny PCB. 20 LEDs are used per digit, which can display numbers 0-9 and letters A-F. The LEDs are laid out in a pattern similar to Hewlett-Packard designs from years past. This layout gives the numerals a more pleasant appearance compared to a more-classic 7-segment design. Several tricks are used to make the devices as compact as possible, such as putting vias in the LED pads. This is normally a poor design technique, but it helps save valuable space.

[sjm4306] has developed a breadboard model, and a more advanced version that has a pad on the rear to mount a PIC16F88 microcontroller directly. We look forward to seeing these modules developed further, and can imagine they’d prove useful in a variety of projects.

For reference, check out these Soviet-era 7-segment displays. Video after the break.

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A Work Light For Hacker Events

May 31, 2019 by Jenny List No comments

If you’ve ever attended a hacker camp, you’ll know the problem of a field of tents lit only by the glow of laser illumination through the haze and set to the distant thump of electronic dance music. You need to complete that project, but the sun’s gone down and you didn’t have space in your pack to bring a floodlight.

In Days of Yore you might have stuck a flickering candle in an empty Club-Mate bottle and carried on, but this is the 21st century. [Jana Marie] has the solution for you, and instead of a candle, her Club-Mate bottle is topped a stack of LED-adorned PCBs with a lithium-ion battery providing a high intensity downlight. It’s more than just a simple light though, it features variable brightness and colour temperature through touch controls on the top surface, as well as the ability to charge extra 18650 cells. At its heart is an STM32F334 microcontroller with a nifty use of its onboard timer to drive a boost converter, and power input is via USB-C.

We first saw an early take on this project providing illumination for a bit of after-dark Hacky Racer fettling at last year’s EMF 2018 hacker camp, since then it has seen some revisions. It’s all open-source so you can give it a go yourself if you like it.

Wireless LEDs Aren’t A First, But You Can Make Your Own

May 28, 2019 by Brian Benchoff 25 Comments

Wireless LEDs. That’s what [Scotty Allen] found in Japan, and if you find something you just have to replicate it.

[Scotty] found these wireless LEDs in a display stand for model makers and gunpla. Because you don’t want to run wires, drill holes, and deal with fiber optics when illuminating plastic models, model companies have come up with wireless LEDs. Just glue them on, and they’ll blink. It requires a base station, but these are wireless LEDs.

After buying a few of these LEDs and sourcing a base station, [Scotty] found the LEDs were three components carefully soldered together: an inductor, two caps, and the LED itself. The base station is simply two coils and are effectively a wireless phone charger. Oh, some experimentation revealed that if you put one of these wireless LEDs on a wireless phone charger it’ll light up.

The next step is of course replication, so [Scotty] headed out to Akihabara and grabbed some wire, resistors, and LEDs. The wire was wrapped into a coil, a LED soldered on, and everything worked. This is by no means the first DIY wireless LED, as with so many technologies this too hit fashion first and you could buy press-on nails with embedded wireless LEDs for years now. Check out the video below.

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Lateral Thinking For An Easier Charlieplex

May 20, 2019 by Kerry Scharfglass 9 Comments

In the practical world we live in, PCBs are often rectangles (or rectangles with rectangles, it’s just rectangles all the way down). When a designer goes to schematic capture things are put down on nice neat grid intersections; and if there isn’t a particular demand during layout the components probably go on a grid too. Routing even the nastiest fractal web of traces is mostly a matter of layers and patience. But if the layout isn’t being done in a CAD tool and needs to be hand assembled free-form this isn’t always as simple. [M Rule] had this very problem and discovered a clever solution, turning things diagonal.

They changed the fitness criteria to the optimization problem that is controlling a lot of LEDs. Instead of minimum pins to drive the goal became “easiest assembly”, which meant avoiding wires snaking back and forth across the layout, a big source of frustration in a big Charlieplexed design. The observation was that if they turned the a rectilinear LED matrix by 45° and wrapped each connection around at the edges it formed what was essentially a large multiplexed matrix. The topology is pretty mind bending, so take a minute to study the illustration and build your mental model.

It looks a little strange, but this display works the same way a normal multiplexed display does but with the added benefit that each trace flows from one side to the other without turning back on itself at any point. To light any LED set the right row/column pair as source/sink and it turns on!

What if you actually need a rectangular display? Well that’s no problem, the matrix can be bent and smooshed as desired to change its shape. At the most extreme the possible display topologies get pretty wild! We’re sure to try thinking laterally next time we need to design an unusual display, maybe there is a more efficient matrix to be found.

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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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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