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Author Topic: LED string saber evolution - this might change the way we think about LED string  (Read 18167 times)

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Offline Obi_1

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Hi guys,

I want to share a new and exciting LED string technology emerging. It has the potential IMHO to change the way we think about LED strings.

To pay credit where credit is due, this opportunity has been brought to my attention first by racemaniac (see in my Arduino lightsaber thread), thanks for him to introduce me this unique technology!!!

So here is the trailer:
Who did not dream about building one day an LED string saber with the possibility for color change? Moreover, people assembling their LED strings know the pain of suddenly loosing an LED, solder joint coming loose, etc.

This just might be the answer to both of these major wishes. There is a new, prefab LED string on the market called neopixel (type WS2812), you can find a lot of offers on ebay, for instance:
1-2-5-Meter 60 Led´s/m WS2812B Streifen Stripe weiss RGB | eBay

Technically speaking these stripes mount LED modules on a flexible PCB, which can be cut at any LED position. The LED modules integrate:
- 3 colour, RGB LEDs in one package
- together with a tiny controller IC already integrated into the package of the LEDs

The controller can be programmed with a 1-line serial interface. It has for each of the colours an 8-bit PWM (pulse width modulation), summing up to 24-bit/LED module. The serial interface runs through the whole stripe, i.e. the aggregate of all LED modules act like a giant shift register, which can be programmed in one go.
To program it, you need only therefore 3 wires:
Wire#1: VDD supply (rated at 5V, but I tried, it's crazy, but it works down to 1.8V! 3.7V is ideally suited to supply the stripe!!!)
Wire#2: 1-line serial signal to program the stripe
Wire#3: GND

That's all!

The programming of the stripe can be done so fast, that you will not notice, so features like flicker, FoC etc. can be implemented very easily. Since ALL LEDs can be programmed individually (yeah, no joking), and the LED stripe can be cut at any joint, it would be ideally suited for Kylo Ren type crossguard sabers. You just make a stripe for the main blade, then 2 sub-stripes for either half of the cross guard, and connect the 3 stripes in series, programming them all together.

As to stability: they are mounted on a PCB, the backside of the stripes have a string 3M adhesive tape, for a blade you can simply glue 2 stripes together back-to-back, wrapped in a diffusing foil it will allow you to duel with it in my assessment. Looks very solid.

I made a video showing how it can be used for lightsaber blade.

The software running on my DIYino prototype board is the so called LSOS written by neskweek. I just included basic drivers for neopixel LED stripes. For the saber FX, all credit goes to neskweek, and racemaniac who started me off this path.

(Disclaimer: sorry for my bad spoken English, just ignore my ranting and enjoy the light show)
DIYino demo of Neopixel lightsaber blade with LSOS - YouTube

This video uses sound fonts from Soundfont.com, home of the best sound fonts ! I especially thank Novastar, Genesis Custom Sabers for their saber fonts (Novastar a and bespinII), and the creator of one of my favorites: Ancient Saber!

If you like Bruce Springsteen, you can also chill out at the end of the video with one of his hits  :afro:
« Last Edit: March 02, 2016, 02:20:33 AM by Obi_1 »

Offline erv

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those strips have a lot of potential indeed. I've experimented this technology back in early 2015 with my tron legacy identity disc that can be seen here
Tron Legacy Identity disc

and it's definitely inline with at least a variant of Crystal Focus LS v8. Though the programability factor is a plus, the drive of the power load and very high current remains an issue.
I also have to insist on the fragility of those strips (especially if you purchase the cheap ebay ones) compared to the "armpit-buddies" technique to built classic led strips.
The corn-on-the-cob results of such a blade (usually not seen on videos which over-flare) is also a problem.

Offline Obi_1

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Now we can enter the technical discussion  :cheesy:

corn-on-the-cob? I guess you mean, that without proper diffusing the individual LEDs might be visible? Yes, this is true, currently this I see as a challenge. Diffusing such stripes is not easy, the LEDs are facing outside and I although the viewing angle is wide (120deg), you can still see the LEDs with a 60 LED/m stripe (the one I use on the video). True, that I did not invest much time into a proper diffusing, just tuck it into a leftover Hasbro LED strip foam.
But the newest, 144 LED/m stripes have the LEDs nearly touching each other, I assume there this problem will not arise.

But there is for sure a trade-off between LED density and power consumption. If all LEDs are driven fully, you have 60mA/LED, considering a 60LED/m and a 80cm long blade, 2 sided strip, it gives you 100 LEDs -> 6A. But this is not a realistic scenario. The 100 LEDs on my video drew ~1A from my PSU. Key is the supply voltage and the LED PWM drives. Although the stripes are specified for 5V, they do not need that much. It's a huge waste of power if you do in fact. Reason is, to protect the LEDs from overvoltage, these modules simply have clamps for each LED color, i.e. if you supply the module with 5V, the red LED needs ~2V, the rest is wasted over the clamp circuitry. But by supplying the stripe from a 3.7V battery, at least you are close to the Vth of the blue and red LEDs, the waste is minimal. And since you have a huge number of LEDs, it's recommended to operate them at the lower end of their characteristic curve.

As to the sturdiness, I do not have any evidence, but I disagree to your statement. I have a few arm-buddies LED string blades (I'm a huge fan of these), but they do need regular inspection/maintenance. The force if dueled with affects directly the solder joints, which anyway have always a tension inside (you can't have the leads completely parallel and straight), so the chance of breaking is there. In these stripes the LEDs are soldered on a PCB with the impact force affecting them perpendicularry to the stripe, the chance of popping them is minimal. I do not know about cheap ebay ones, I buy them from German sites on ebay.
Anyway, LED string blades are never meant for real stunt action, they are for display.

All in all I see big potential in it, anyway the only feasible way so far to build RGB LED string blades, in that it has no alternative so far. It also has a distinc advantage when it comes to wiring, only 3 wires, that's the bare minimum.

Offline EXAR KUN

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Love to see this in action with the 144 LED per meter string. I think that would nullify the corncob especially if you had two stuck back to back. MIght be some darker areas along the sides but even on standard LED string there is those legs that run down the side nothing you can do about that. Multiple diffusion layers will help to look not noticeable such as first the foam, then the TCSS diffuser (if can fit) then the TCSS trans white tube will also help here.

Wonderful, wonderful work here I thoroughly enjoyed your video and loved, loved, loved the 'fire' technique effect I think it was so fantastic like Archangel Gabriel's flaming sword. Amazing.

Truly this technology will eventually allow for the most configurable and realistic lightsaber experience... and you'll get to still keep all your limbs!

Really,... Obi your tests are fantastic keep doing this wonderful work I hope you can get those electronics into your saber one day soon and I'll see you swinging that fire sword around. Wow. 48 thumbs up great  :smiley:



Offline livebyhonor

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I was considering making a go at these for a saber project. NeoPixel Diffused 5mm Through-Hole LED - 5 Pack ID: 1938 - .95 : Adafruit they are also neopixel but they are in the standard 5mm LED look. (there is also a 8mm version) so you can string it like we currently do it. the difficulty would be the soldering of the leads since there is no + and -, but rather + - data in and data out. but this would yield a very uniform blade look. but at the price for 5 your looking at a rather spendy test blade.

Offline erv

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I've tried the 8mm ones about 10 months ago. Not so bright and a little slow. I'm going to test the 5 mm soon though

Offline EXAR KUN

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Those shorter legs could be small issue. When I made a blade with 12mm LEDs I had to amend each leg with a longer lead it was a major PITA. Totally worth it in the long run but just saying that adds some solder joints and material. Hopefully if these work out we can find some with standard length legs although these could be long enough we will have to see with a test section or blade. Totally awesome stuff.



Offline CET

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Back to back would decrease viewing angles. I wonder how 3 of those strips could be fixed to and facing out from some sort of center rod. Wrap it up in a few layers of foam wrap and slide into a white translucent blade for extra diffusing and we could really have something.

Just not sure what type of center rod or affixing method would work best. Maybe very small gage zip ties and a solid nylon rod (1/4" or 1/2" diameter)?
« Last Edit: March 02, 2016, 12:04:15 PM by CET »

Offline Obi_1

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I was considering making a go at these for a saber project. NeoPixel Diffused 5mm Through-Hole LED - 5 Pack ID: 1938 - .95 : Adafruit they are also neopixel but they are in the standard 5mm LED look. (there is also a 8mm version) so you can string it like we currently do it. the difficulty would be the soldering of the leads since there is no + and -, but rather + - data in and data out. but this would yield a very uniform blade look. but at the price for 5 your looking at a rather spendy test blade.

Hey buddy, thanks, just the thing I was looking for! I recalled I had seen this kind of cross-breed LEDs but I could not find them. WIth these 5mm format LEDs it would be indeed possible to build a string blade just like we are used to do it.
'course the 4 leads might make interconnects a bit complicated, I think there a similar stiffner/pcb combo like used by the Hasbro LED string saber could be feasible. After all the wiring is simple, even simpler than the Hasbros, all the signals just run the whole length of the stripe. It would be like a ladder, with the rugs holding the LEDs. IN such a design a lot less LEDs would be needed, so power consumption would be less of an issue. I guess ~70 would be enough.
I still have to figure out if the small cap is really needed. The smd 5050 LEDs all have them on the pcb, 100nF filter cap for the controller I guess.

Great feedbacks, always a pleasure to share ideas with this community! I can learn so much out of it myself, very rewarding!

Offline Wolf69

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What a coincidence!

After building ly first string blade and being a bit disapointed i was watching sole leds on aliexpress and find exactly this:
1m/4m/5m WS2812B Smart led pixel strip,Black/White PCB,30/60/144 leds/m WS2812

I was really curios about it but could only find a quick video on youtube where someone use it for a lightsaber.

I was tempted to buy two but the cost for 1m/144 was high, 17$

And i dont know how to drive it to choose the color.
Would you mind to explain a bit more about it?

How bright is it compared to a regular home made led string?

I m really glad to have been on the "unread section", thing i dont usually do!

Offline CET

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$17 for 1 meter of 144 LEDs sounds like a good buy to me. A little more expensive than getting bulk 5mm LEDs, but worth it, IMHO. The strips I've seen in electronics supply stores around town have about half as many LEDs per meter for 3x more money.

Offline Wolf69

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Price for 100x5mm led is 3$, so much cheaper but i agree 17$ is not that high but 2x17$ for maybe somthing that could be useless, it could be throwing money!

That why i m really interested in feedback to laybe try it myself

Offline EXAR KUN

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Price for 100x5mm led is 3$, so much cheaper but i agree 17$ is not that high but 2x17$ for maybe somthing that could be useless, it could be throwing money!

That why i m really interested in feedback to laybe try it myself

5mm LEDs at three cents each are guaranteed crap. 



Offline gucabe

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Offline JakeSoft

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Wow. That's pretty cool. I don't do string blades because the idea of spending hours soldering LEDs together sounds a lot like torture to me, but this looks like a nice flexible and easy alternative.

 

retrousse