[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.
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.
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.
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.
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.
GaN or Gallium nitride is a wide band-gap semiconductor that has been employed in the manufacturing of FETs that are known to have higher power density due to its high thermal capacity while increasing efficiency. In the the case of the tunable LED, the key has been the doping with Europium for creating energy bands. When an electron jumps from a higher band to a lower band, it emits energy in the form of light and the wavelength or color depends on the gap of energy jumped as per Plank-Einstein equation.