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Thread: Am I forgetting something/Math check

  1. #1

    Default Am I forgetting something/Math check

    Hello everyone,

    First time saber builder here. Been building props though for 8 years. Handy with soldering iron and tools. Almost passable knowledge of electric theory. Would love a once over from the pros to catch any potential mistakes, and to make sure everything will work together.

    The Hilt (empty):
    Emerald Knight from SaberForge. Unscrews into 4 parts (ASP).
    Emitter (ID 1" length 3 & 3/8ths)
    switch section (ID 1" length 1 & 5/8ths) Already has two 12mm holes for switches/power plugs
    Body (ID 1.125", length 5")
    Pommel (measurement probably doesnt matter)

    The plan: Spark 2 board for light and sound, using 1 illuminated momentary switch. Second switch hole in switch section will be used for recharge port/kill key so i dont have to take it apart to charge. Saber is mostly for show and spinning, but i'll pick up a second blade for dueling, so it will need to take some punishment. Saber color is green, no plans for color changing/mixing. White flash on clash. I don't care about lockup or blaster deflect. GGW tri cree wired in parallel.

    The parts (from various other places):
    12mm power plug
    kill key
    3D printed sled that holds spark 2, speaker and battery holder. Not sure if i should name drop which one so i'll remain silent for now. Claims it is for 1.12" ID sabers. 3.75 inches in length.

    The parts (from TCSS):
    32" blades, TCSS style show and battle.
    GGW cree xp-e2
    Star Thermal pad
    cree/rebel lens holder
    18degree tri-rebel/cree star lens
    Premium 28mm speaker
    12mm anti vandal momentary red ring switch
    Heatsink module for 1" ID tubes with center hole (will this be too tight a fit for my emitter section?)
    panasonic Li-ion 18650 3.7v 10A 3200mAh protected rechargeable battery
    18650 single cell holder (i'll have to modify it a bit to fit the battery i've selected, mostly just to keep it from rattling around.)

    And now everyone's favorite. the resistors.

    I did math by hand and got this

    2x .5 ohm 3w resistors for the Green (saber color)
    1x 1 ohm 2w resistor for the white (foc)

    but then i used from the tutorial and it told me i need 3x 1ohm 2watt resistors. one for each LED. (values for the calculator: source voltage: 3.7, diode voltage: 3.7(green) and 3.15(white) with 1000mA current)

    could use some help with where i went wrong in my math or if i should trust the website.

    illuminated momentary switch should solder onto the accent lighting pad for the spark 2 so i dont think i need a resistor for it.

    wired in parallel, would my math be correct and did i select the correct resistors? followed the sticky and did the equation but would still like an expert's opinion.

    Thanks for taking the time to read this and help me out, you guys rock.

  2. #2


    That resistor calculator won't give you values below 1 ohm. The values you came up with by hand are fine.
    We all have to start somewhere. The journey is all the more impressive by our humble beginnings. for the lazy man's resistor calculator! for getting resistor values the right way!

  3. #3


    Thanks man, i appreciate it


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