It’s an area I’ve been playing about in for a little while, with mixed results. In fact, I’ve been half-way through a project for about nine months, and this was the perfect excuse to finish it off. Like many makers, I’m particularly fond of WS2812B LEDs – sometimes known as NeoPixels. These are addressable LEDs, so there’s one data line that can control an almost endless series of LEDs. Each LED has a data-in and data-out pin – just connect the data-out of one to the data-in of the next, and you can drive this whole string off one pin on your microcontroller.
WS2812Bs usually come either as surface-mount components or soldered-in arrangements, such as long strips or matrices. However, there is another form: APA106s (not to be confused with APA102, a different chainable LED). These through-hole components look a little like large regular LEDs, but with four legs. They’re a great choice for circuit sculptures as they’re easy to work with, and you can create impressive lighting effects with very few wires. While circuit sculptures don’t have to have LEDs, the reflections on the brass rods give great visual appeal and help show off the structural elements of the project.
The circuit itself is really simple: the outer O of the 8 is ground; the two inner Os are VCC (5 V); and there are also breakouts for the first data-in and the last data-out, so these displays can be chained together. The only extra components needed are capacitors for smoothing the supply – with this many LEDs flicking on and off, fluctuations in the supply voltage can cause problems. I added a couple of 10 µF capacitors between ground and VCC (one in each loop), and that got everything working nicely.
The biggest challenge with building the sculpture is holding everything in place while you solder it. I used a couple of tricks. First, tinning the brass rods before joining them, either to each other or the LEDs, makes it much easier. Building up 2D parts from brass rods (such as the outer and inner loops) can be done easily by taping them in place on a heat-proof mat. Finally, use a jig to hold the LEDs in place while soldering them up. I did try a different approach first – pushing the legs of the LEDs through a piece of paper will hold them in place – but it’s not that secure, and it’s easy to rip holes that are too large. If you have access to a 3D printer, the jig is a much better approach.
The only slightly tricky bits are adding an extra bar across the middle to supply ground to the three LEDs in the mid-horizontal, and a bar connecting the final LED in the main loop to the first LED in the midline. I used a third hand to hold these in place.
I’ve tried using a variety of different brass rods over different circuit sculpture projects. You can get brass rods for model-making in a range of thicknesses, but they tend to be expensive. I use brass welding rods which are cheaper, but don’t come in the really thin sizes. I have a few thin model-making rods for when a project needs to go into a pin header hole but, most of the time, I use the welding rod.
I then created a Hackaday.io project page and entered it in the contest – you can see my entry at hsmag.cc/v3nrwl. You can download the 3D-printable STL file for the jig there, but may find that you need to tweak it up or down a few percent to make it fit.
That’s my circuit sculpture, now over to you. What can you come up with to decorate your house or hackspace? If my project hasn’t given you enough ideas, you can take a look at the other entries at hsmag.cc/SL9VmS.
