View Full Version : LED bulb on hilt with EL blade...which resistor?

04-15-2007, 08:56 AM
Hello all...i joined up last night because i'm about to buy the set up for a Blue EL blade....i have the hilt already built and i'm going to purchase the inverter and the blade today or tomorrow. Right now i have a High Intensity Blue LED install on the hilt as decoration and it's wired into a 2 AA battery holder to light it up....here is the specs on the LED: http://www.radioshack.com/product/index.jsp?parentPage=search&summary=summary&cp=&productId=2102851&accessories=accessories&kw=blue+led&techSpecs=techSpecs&currentTab=summary&custRatings=custRatings&sr=1&features=features&origkw=blue+led&support=support&tab=features

I know that the inverter has a 9 volt battery attachment....and i know that wiring up that bulb to the 9 volt battery will burn it out....i need some advice of what resistor to use in my set up to power up both the blade and the LED bulb and not blow up anything....Please any help would be greatly appreciated. thanks!!

Lord Maul
04-15-2007, 10:09 AM
the simplest way would be to use two circuits. one for the el, and another for the led. the EL one it looks like you have figured out.

for the led one, i think that you could do a 9 volt battery with a hundred ohm resistor (not sold here). you would have two switches, but it's easy enough to have tim machine another hole for ya if you are doing a MHS setup

04-15-2007, 08:31 PM
Thanks Lord Maul....but i thought i could just toss in the right resistor according to this diagram that was in EL Hilt Building tutorial:

I'm confused :shock:

Lord Maul
04-15-2007, 08:40 PM
that would work fine :wink:
i just threw out one way to do it. there are many.

if that was in the hilt building tutorial, then tim made it so you know that it works

04-15-2007, 08:53 PM
Hehe....no worries....is there a way to figure out which resistor i need? I used this http://led.linear1.org/1led.wiz

and i entered

source voltage: 12v (i'm going to go with 12 instead so i dont lose brightness)
diode forward voltage: 3.7
diode forward current (mA): 20

and it gave me: "The wizard recommends a 1/2W or greater 470 ohm resistor. The color code for 470 ohms is yellow violet brown."

Does this sound right?....i've been searching through the forums and i'm seeing people using 270 ohm based on there set up and i'm getting more confused

Lord Maul
04-16-2007, 02:28 PM
it says that in the pic too :wink:
a 470 ohm 1/2 watt resistor will do ya fine

04-16-2007, 03:00 PM
Sweet thanks!!!...now for my question before ordering....since i'm going to 12 volts now....i was hoping to get the 8 AAA battery holder but from the pic, it doesnt look like it has the snap connectors and the top like the 8 AA one does....do i just cut the 9 volt attachment and then attach the 8 AAA holder accordingly?

Lord Maul
04-16-2007, 03:22 PM
on that diagram, blue is negative and red is positive. on the 8AAA battery pack, black is negative and red is positive. it is the same thing, just a different style of battery so to speak :wink:

04-16-2007, 04:17 PM
Sweet thanks again Lord Maul....i'll order the 8AAA holder then so i have some extra room to work with....there are two screws holding the bottom grip of my hilt in place...at least this way i can leave the screws there and i dont have to worry about reattaching the grips it somehow...thanks again for all your help with my newbie questions.

Lord Maul
04-16-2007, 05:11 PM
your questions weren't actually that newbieish
they were fairly technical :wink: