SMD LED Lightsaber Video

I'll go into more detail on the SMD LED lightsaber tomorrow, but for now here is a video and photo of the end product.

Thanks
CD

Fibre Optic Video on Youtube

So I've also just uploaded my first every video on youtube.

It's not the most exiting, but shows the fibre optic cable in more detail.

More to come!
CD

Fibre Optic

So a quick summary of how far I got with using fibre optic cable, why I abandoned it, and why I hope to try and use it again.

Fibre Optic Cables?
I'm no expert, but I'll quickly explain what fibre optic cables are and how they work.
Fibre optic cables are transparent/translucent cables that make use of the principle of total internal reflection to transmit light from one end of the pipe, to the other, with no (or minimal) leakage of light out of the sides of the cable. Most (and the one I used) is one 'cylinder' of material coated with another material, although both are transparent, the light bounces off the boundary and stays inside the cable until it reaches the other end. Also, if a   deep enough scratch is made in the fibre optic cable, light will bleed out of this scratch - I'll come back to this later.

The Initial Setup
Initial setup I used is shown below.

To power it I used 6xAA batteries in a holder to give a 9 Volt battery pack - I did this because it is nearly identical to the lego power functions battery pack and I hoped that I could have made the Light up lightsabers compatible with the new power functions. (I have recently abandoned this idea because power functions cables are quite expensive >£4 on bricklink).

Hidden in the little black 2x2 block are a resistor and LED. An LED is a light emitting diode, it gives of alot of light with little power, it doesn't get hot like a light bulb, and the light it gives of is quite directional which is ideal for this application as I want as much light as possible to pass through the fibre optic cable. The resistor is used to limit the current to the LED, to keep it running and stop it blowing out, it is also used to drop the voltage because the LED only wants 3V. It does this by taking out the extra 6V and expelling it as heat - this is pretty inefficient, ideally I would use a 3V power source like a coin or button cell but I wanted the end result to be power functions compatible so I opted for this, inefficient, option. I should also note that although the extra 6V is expelled as heat, the block doesn't get too hot, even after about 2hrs continuous use.

A close up of the battery pack and the insides of the box:

Add caption

The black heatshrink around the LED is to stop too much light bleeding out of the sides, lighting up the block. What you can't see too well is the small hole drilled into the top of the LED to attach the fibre optic cable. A photo with the fibre optic cable connected and the 'board' back inside the box is below.

Here you can see the fibre optic cable bleeding a bit of light along its length, at the tip I have put a series of cuts into the cable which lets the light pour out relatively evenly along the top 1cm of cable. I drilled a hole in the hilt and first centimeter of the blade to give the following result.

The portion of the lightsaber with the fibre optic cable in was very bright, this was taken in broad daylight with additional lights and the camera has picked it up pretty well. I have had real difficulty drilling further into the blade - I really wanted it to run the whole length of the blade but the hole was always at an angle and by 0.75mm drill bit is little more than 1cm long. In the future I would like to try and build some form of drilling jig/holder for the blade and maybe I can improve this.

Inside a Minifig

My next attempt was mount a minifigure ontop of the black block and run a fibre optic cable through the legs, through the torso, down the arm and taking a loop outside the body into the lightsaber. This was a nightmare. I wouldn't recommend it to anyone - it involved hollowing out the body, drilling holes in the legs and matching holes in the hips, drilling more holes in the arms and a nightmare trying to bend the fibre optic cable through the tight turns of the torso. It turns out sharp bends in the fibre optic cable cause more light to bleed out, so this resulted with lots of light bleeding from the torso.

However, with the LED and resistor out of the block, and Obi-Wan's insides butchered the end result is below.

The light from behind is from the uncovered LED. A lot of light is bled from the fibre optic cable through all the sharp bends and thus the lightsaber appears less bright than the red one earlier. Also, and a more likely culprit for lower brightness is that the fibre optic cable is not fed into the lightsaber blade, instead it is sat just below it, lighting it from below.

And finally, for your viewing pleasure, a video of light-up Obi Wan.

As you can see, Obi-Wan's lightsaber isn't very bright, due to the bends in the cable and it being a bright day. Feeding the cable into the blade looks really good, but there are limitations on how far it can be fed in, if it could cover the length of the lightsaber that would be incredible, and I personally think it would be better than any commercially available alternatives, but unfortunately I can't produce it.

The verdict

In summary, fibre optic cables might work for static lighting inside MOC's, but unfortunately it is not flexible enough, bleeds too much light and is generally a pain to work with for me to continue using it.

If there was any way I could drill a 0.75mm hole the whole length of the lightsaber then it would be great for that alone, but I might light the lightsaber blade from directly below in the hilt using an SMD LED and use the fibre optic just to spread the light outwards rather than up the blade and out the top.

Any comments, suggestions, complaints? Please leave a comment.

Stay tuned for tomorrows post on using SMD LED's.

Hello World

Light Up Lightsabers

So here's my first ever post, just a really quick summary of everything I have attempted so far and how it went, it's a little technical - I'll take some time in my later posts to really explain the jargon and how/why it works.

I have been trying to create a lego light up lightsaber for quite some time now. In the past I have tried using 1mm LED's in the hilt, but these produced next to no light. 

I have also tried using 0.5mm and 0.75mm fibre optic cable to carry the light from a 3mm ultra bright LED through the hilt and into the blade, but I found the fibre optic cable too brittle and not flexible enough. Also the fibre optic cable bled some light, to hide this I covered the fibre optic cable with heatsthrink. It worked ok, but the lack of flexibility eventually knocked out this option. However feeding the fibre optic cable into the 'blade' itself produced a much superior lighting effect than simply lighting from below, I'll try to re-incorporate this in some way in a later revision, see the photo below.

Fibre optic light up lightsaber in broad daylight.

I have finally settled with an idea I borrowed from  http://lifelites.com, which is to place a tiny tiny SMD LED inside the hilt and run a thin cable out the back - it works really well. The SMD LED's are absolutely tiny! I settled for a 0805 package size, which is near enough to 2mm x 1mm. The photo below shows just how small they are.

After alot of frustration I managed to solder the LED to the wires and run a cable into the 2x2 block which houses a resistor, this is connected to a PP3 cable (a 9V battery connector) and works reasonably well. I have only completed it tonight so excuse the grainy photos from my phone, but here is the end result.

So that is the progress to date, in the next couple of posts I'll try and fill in what has been about 3 years of on and off attempts to make a light up lego lightsaber.

Enjoy,

CD