This post will be talking about how the Telecortex LED panels are constructed. The aim was to make something cheaply, quickly and for it to be transportable (light). There are two sizes of panel to suit the 2V icosahedron dome design, the design was planned out in CAD and then transformed into the real world with a lot of time and effort by myself and friends.
The LED panels consist mainly of a a material called coreflute, it is basically a plastic cardboard, often used for signage and is just about perfect for our application. The flexibility of the coreflute has caused us some issues (talk about that later) but it is quite a robust material and very cheap.
To cut the large rectangular coreflute panels to size we built a temporary table saw out of plywood and a circular saw (I wouldn't advise doing this but necessity is the mother of all inventions). We also built an adjustable angle guide to aid us in cutting the sheets of coreflute consistently, unfortunately I don't have any photos but it was built from two pieces of striaght wood, a few hinges and a large piece of threaded rod to act as the adjusting side.
The size of each LED panel meant that we couldn't fit the whole panel in one contiguous coreflute sheet, to solve that we cut each panel as two pieces and then using thin wooden dowels pushed into the corrugations. Hot glue seems to be one of the only things that sticks to coreflute, we used a thin strip of coreflute hot glued along the spine to keep the two halves from separating.
The panels were marked out where an LED strip should be placed, the LED strips were cut to length and then carefully stuck down along the marked lines. We cut wires to the right length to go between the LED strips in the centre to carry power and 2 signal wires were done between the start and end of each LED strip to form a zigzag pattern of LED strip.
Due to the flexibility of the material we were getting the solder joints breaking over time due to metal fatigue. To mitigate this we have added aluminium extrusions to the front and back of the panels, this stiffens it up significantly and prevents the hand soldered wires from breaking due to metal fatigue.
Each LED panel has a 48V>5V power supply as discussed in one of the prior posts, this is cable tied to the backside of the panel. The photo below is prior to adding on the aluminium extrusions for rigidity.
The first iteration of the control electronics simply had a 4 pin automotive style connector on each panel which had 4 connections, 48V, SPI data, SPI clock and ground. This was good for a quick assembly and cheap but we were getting signal drop outs which would cause large visual glitches.
This was a lot of labour to produce each panel but they look amazing when running together.
In a later post I will talk about how we upgraded the electronics to fix the electrical interference and visual glitches by using a CAT6A network cabling instead of individual wires like the earlier version.
