[Dan] is an element collector, someone who gets his socks knocked off by bismuth crystals and the orange vapor of bromine. Of course every element collector needs a proper display case, and since the periodic table table idea is cliché, [Dan] decided to build an elemental display that’s also a really awesome LED wall.
The build started off as most do with a few sheets of plywood and 120 acrylic shelves for each item in [Dan]’s collection. The real magic happened when [Dan]’s buddy [Bill] was called in to make the display a little more interesting.
Behind each acrylic shelf is a three-LED section of a LED strip, each part of the periodic table having a different color. The 120 individual shelving units are broken down into 16-shelf groups, each driven by a custom LED driver board. These driver boards are connected to a master Arduino with phone cables and make wonderful use of a very neat TCL5940 Arduino library.
The elemental display has a few options; all-on, twinkling, an Apple ‘breathing’ mode, and a graphic eq, as shown in the video after the break.
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Even if you’ve overcome your fear diddling about with tiny SMD components, applying solder paste – especially if you’re populating more than one board at a time – is still a chore. The pros use very expensive laser cut stainless steel solder paste stencils, something still a bit out of reach to the casual hobbyist. [Felix] solved this problem by making his own solder paste stencils very cheaply using empty soda cans.
The process begins just like any other home etching tutorial by lightly sanding the un-bent aluminum can and applying the etch resist via the toner transfer method. Etching is done with off-the-shelf HCl and hydrogen peroxide, resulting in an amazingly clean stencil comparable in quality with a professional stencil.
Sure, going through a dozen-step process to make a solder paste stencil may not be as convienent as [Cnlohr]’s toothpick and tweezers method, but [Felix]’ method is just about up to par with extraordinarily expensive laser cut stainless steel stencils. Not bad for something that came from the recycling bin.