It is difficult to know if I really had “a new ideaâ€, but I will at least share some details on an experiment. Space Windu has made a lot of interesting LED-string blades and I found the color mixing blades particularly interesting. (See for example his viridian, ice-blue and platinum). Clearly these blades are the source of inspiration for my experiment. Since the procedure I used was a little bit different, I think you may find it interesting. I have made a white-blue mixing, where I use four 3mm LEDs in a square, where the LEDs in diagonal (seen from above) are of the same color. The idea is that the blue color always will have a white beside and behind and that this will blend the colors.
Building techniqueI show the procedure in the photo and I add some explanations below. First I consistently start to bend out the longer leg, and for the white I bend the shorter upwards, while for the blue it is downwards. To fit the LEDs in a square I sanded by hand the inner part. I drilled a hole in a wood board to make it easier to drop a little super-glue in the middle. This was an important improvement as I started out using the helping hands – which was really slow, and also the LEDs sometimes where not perfectly on the same height. Notice that the legs that are closer are always negative leads.
The next step is to join these legs, and I did this by bending one below (and upwards) and thereby using it to bend down the other. I soldered these connections and cut away the ones pointing upwards. I call this square of four LEDs a
set. Next I joined these by bending them by hand. Basically I introduced one set into another and bended out the legs of the set in the position above. Once all the four legs were more or less in position I used a tool to press them together. When I started I had the tendency to get the sets too close to each other, but I later improved my control of the distance.
For the blade I made 6 segments, each consisting of two sections of 9 sets. Accordingly, this means 18*4=72 LEDs per segment and a total of 432 LEDs for the blade. Since the sections of 9 sets had different length I simply ordered them and used the shortest closer to the hilt. I also used super glue to make the string blade rigid, even between segments.
Specification of LEDsThe LEDs that I have used are actually very cheap, but I have no complaints about them. They are flat top with the following specifications; Blue, 3.2-3.4V, 5000-6000 mcd, White, 3.2-3.4V, 16000-20000 mcd. It says "Power Angle" 120-140 degrees, but I am not sure if they actually refer to viewing angle. Price with shipping is less than 6 Euros for 100. (I am not sure about rules on the forum, but if I am allowed, I will be happy to share the source).
I had bought a lot of blue LEDs, but only two packages of white. The packages actually included more than 100 in each, which made it possible to build the blade including 216 white LEDs. I lost a few on the way, but almost all was due to bending and gluing mistakes.
Evaluating the resultI am overall very satisfied with the work. The technique gives a fairly good blending of the colors, but I work with a sanded polycarbonate tube, and the diffusion is not perfect. I have noticed that with lower power it becomes worse. I used a foam-wrap for diffusion, but I didn’t include that many layers, because I wanted to be able to insert the blade in the polycarbonate tube without creating wrinkles. This means that I have less diffusion in the blade compared to a try-out (of only five sets) that I initially did. In the try-out the blending was perfect. I include some photos below. I make some comparisons with a green blade that consists of 80 5mm LEDs; 540PG2C, (3.0-3.6V, mcd 16000, 40 degrees viewing angle.) The photos of the blade were taken during daytime (but in shadow), except the last photo, which obviously is during the night.
Difficulties to keep in mindWhen I had finished, I had used all of my white LEDs, which meant that I had to use some sets that are a little inconsistent in height (for example a LED turn out to be slightly above the others). This is something that should be avoided, because the idea is to have the LEDS in a set exactly on the same level.
In the process I made some poor solder joints, and I had to spend some time testing and re-soldering. This is, of course, due to lack of experience and I improved on the way. On the good side, with more sources of light in each set, I do not find any problems of shadows on the blade, despite using quite a lot of solder.
I have some heat problems at the first section, and some of the foam seems to have melted. I have reduced the brightness a little bit. This problem could actually be related to the previous. I still have a poor contact in this position and when it is lost, the rest of the LEDs will get too much current.
I was also a little careless when wiring the common positive and the negative to each segment. I could have made these connections smaller (and closer to the core). This would, possibly, have allowed some more foam for diffusion.
Initially I wanted to keep all legs to be able to fine-tune a test version with resistors to obtain a particular mixing, but I never tried this because it was too many legs and the bending was close to impossible. I also had an idea to make the segments of the different LED-strings inconsistent in length to obtain a smoother light-up effect. This was also too messy, and I dropped the idea.
ConclusionsThe blade is very bright, and the blue is clearly present on the surroundings, while the blade itself is very pale (close to being white). Some blue parts are still visible to the eyes, but with minor improvements I think this building technique can provide a good “white core†blade. The improvements that should be done are: being more careful in soldering the positive and negative wires to allow a little more foam for diffusion and using a trans white blade or some other kind of “professional†blade tube, instead of the sanded polycarbonate tube. Maybe this would also allow for more foam to be included in the wrap, if wrinkles would be less visible. (I actually don’t have any experience of these options, so please let me know what you think!)
It is also possible that using white and green would be even better as the green LEDs that I have are brighter (12-14000 mcd) and closer to the white LEDs (16-20000mcd). I will make more blades mixing colors in this way. Next up is white and green, but I may also try blue and green.
I use the blade with the DIYino board and LSOS. Hopefully I will provide a video to show you how it looks like in “actionâ€.