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Thread: Not quite an EL question, but close. LED String

  1. #1

    Default Not quite an EL question, but close. LED String

    Hello all,

    I've been working on "upgrading" one of my LED sabers to use a removable LED string blade. I'm using a PC 1.6 with 7.4V, and have ~90 LEDs set up in a series-parallel setup (~45 in parallel with each other, in series with another 45 in parallel). The listed drop on the LED's is 2.8-3.4V, with a 20mA draw, 2000-6000 millicandelas. I followed the setup from Slothfurnace, where the blog post showcasing his Luke ROTJ V2 showed exactly how to set it up. The difference between his string and mine is that he has 6 segments of 16 LEDs, where I think 8 LEDs are in parallel at a time, in series with the other 8 (I hope that makes sense to you all). My goal was to use only 2 wires, and use the 2.1mm power jack commonly used as a recharge port to power the blade, such that the blade orientation wasn't important.

    My current problem is that the LED's just are not bright enough. I don't have the voltage to turn on more than 2 or 3 series LEDs. I have plenty current available. The 2 series lines I have, with the current I'm giving it (a setting of 50 in the old config file), the level of light is sad. Slothfurnace uses a CFLS.

    What I need is more voltage to put into the blade, allowing for another series set or two. Then the current I have pumping through should be more than enough. In the TCSS store, is that what the Power Xtender is for? It doesn't seem to be discussed in the PC 3.0 manual. Or is it just the CFLS has that much more potential power for the main LED that he could power that many series sets?

    This is not a Halloween deadline anymore. It was, but it is no longer possible for that to happen I think. Is it possible that it may just be my LED's are too power hungry or awful?

    Please and thank you for any help


  2. #2


    Did you try to measure the voltage between your 2 wires when you power the blade? It could be that voltage is lost on the way through a bad contacting/soldering, even the 2.1mm jack might be suspicious for voltage drops. Anyway, grab your multimeter and check the voltage.
    AFAIK the PC will not limit the current, at least if you set the config to enable the max power. If you have 90 LED's and you subject them to 7.4V (max should be 6.8V for 2 in series), the LED's will consume min 90x20mA=1.8A, that should be still OK.

    But I do not get your point when you write "2 or 3 series LED". With the blue color you want to have, 2 in series will be max you will get with 7.4V, 3 in series would be possible with a red or yellow Color, but that is the max serialism. The statement "I have plenty of current available" is also not quite right. You have a voltage source, that is what you can select. It has a max current it will shut down upon reaching (that is if you use protected cells), until that it will give the current the circuit draws from it. With the config settings, you do not increase, you can only decrease the current. So maybe check that value 50, it's probably written in the Manual which is the setting which will not limit the current.

    BTW, power extender is not going to help you. And also, CFLS is a powerful electronics to control you effects, but it does not give you much more power, so I think your problem lies somewhere else. Sorry about Halloween though. Let me know your Progress.

  3. #3


    I'll measure later tonight. I've misplaced my good digital multimeter, and I need to buy a new one.

    I was unaware the current setting had an unlimited setting. I have the PC 1.0 manual on a uSD card in a box I need to get out of the garage. I just remember setting it to 33 for my single green Luxeon (I'm pretty sure it was 33 at least).

    I also recently purchased a RBG Tri-Rebel, so maybe my purple Halloween can be saved The LED string is pink technically, but it's close. At college we fought with my lightsabers often, and I plan for the LED string to be a show blade, and switch back to flashlight mode (the Luxeon) for dueling.

    I'll post pictures of what I've got hopefully tonight as well.

  4. #4


    OB1 didn't mean to say there is unlimited current available to you using the settings, he meant you can limit the current by adjusting the "led=" value. The maximum output for the PC 1.x's was 2A (I still have the manual on my computer), so you should be fine as far as that goes.

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  5. #5


    Correct. I knew it was 2A from looking at the PC 3.0 manual. Each LED listed a 20mA draw, so 100 should have been possible, and I had about 90. I think it's just the LED's now, myself. 2000-6000 mcd (lumens) is not a lot for single LEDs like that. I'm going to repeat the process with my Green LED's to see what happens, as they are rated at 8-24 lumens each.

    I managed to get my RGB working with Magenta (I want more blue in it!) for Halloween, but just barely, which will be a new question on another board I guess. Weirdest thing. My old engineering lab partner and I couldn't figure it out.

    Would you be able to attach or share that manual, Jay Gon Jinn? I couldn't find the old uSD. I found my spare light meat, though, which is nice.

    Also, is there a way to move this to the LED strings space? My brain totally skipped over that section when looking for where to ask all this.
    Last edited by JGMJacobo; 10-31-2014 at 07:41 AM.

  6. #6


    Hello again,

    My last reply made all these promises of "tomorrow I will do this," but the pre-Halloween shopping and post-Halloween hangover took precedence.


    That is what I ended up going out with for Halloween. RGB from TCSS, red and blue activated, though blue was being difficult and wasn't as strong as I'd hoped, leaving it pretty much magenta.. Will probably post something in the LED threads asking what everyone else's normal setups are.

    Anyway, this next picture shows my pink/purple LED string.


    I've come to the conclusion that 2 series portions is too much of a voltage pull, and that the maximum brightness is too low to do very well. Is there a sort of unofficial lower limit that the saber community accepts?

    I have green LEDs right now rated at 22 lumens per LED (not working, for whatever reason. I can't get them to turn on), and my next idea to get the purple string going would be blue 16 lumens LEDs, with red celophane inside the tube.

  7. #7


    Could it be by chance that purple LED's have a higher threshold voltage? That would explain some of your Problems with not enough voltage. I bought some IR-LED's the other day (basically depp blue to purple) and they have an even higher Rating that blue and green (I recall typ 3.6V and max 4V or above)...

  8. #8


    Mixing blue led's with a red diffuser is not going to work well, either. Filters are subtractive, they block everything except the color of the filter. If you'd rather use that method, i'd suggest getting white led's and a purple/violet filter instead of trying to mix the blue led's with a red filter, which is what Master replicas did with their Mace Windu FX. It didn't look purple at all, but was pink/magenta, and very dim.

    And I can't add the pc1.6 manual as an attachment, it's too large of a file.

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  9. #9


    Shoot. I was hoping the celophane would work. I've got the green LEDs started a little bit, and they are tons brighter (obviously), so I just think it's the rating of the pink LEDs that is sub par. These are the ones:

    I spent a moderate amount of time looking for 5mm through-hole LEDs online to use. Do you know if there is a better supplier? I've seen Makoto recently on the forum, and he's got LED strings down to a science; my setup is serf-level in comparison.

    Jay-gon, could you just peak into the file and tell me what the non-limiting setting for the LEDs is? I imagine it is either 0 or the maximum number in the little equation the board used to calculate it.

    Also, thank you both very much for your insight.

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