lightsaber question

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TJack

Master Member
Community Staff
RPF PREMIUM MEMBER
I have what I hope will be a fairly easy question for someone here on the forum. As I started to piece together my Taun/Luke costume, my wife decided to surprise me by ordering a lightsaber for me at the same time that she bought our boys' costumes.

Unfortunately, she purchased the Obi Wan one for me and because it was not going to make sense to ship it back I decided to keep it. Not to mention that she would be devastated if I told her that she bought me the wrong one :)

This particular one is lit up by a small bulb which barely puts out enough of a glow to make it light up. I was wondering, is it easy to swap it out with a high power led? If possible, can someone advise me what needs to be done? Thanks in advance.

This would be the one she purchased:

Obi Wan Kenobi Blue Star Wars Lightsaber - Star Wars Lightsabers



 

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blip

Sr Member
If you can solder then it's not that hard.

First take the saber bulb and see what (v) voltage it is.

Second, note the specs of the superbright LED you choose. Tell me what (mA) current the shop says it needs to run. Jaycar has the data on the trays.

Then use the equatioin V+IxR to calculate the resistor you will need to put in line with the LED to stop it burning out.

eg

BULB voltage = 6 volts.
Superbright current = 200 mA or (0.2 of an amp)
V= I x R so transpose to find R.
R= v/I
R= 6/0.2
R= 30 Ohm resistor.

Give me the real values and I will walk you through the circuit.

Remember a LED unlike a Bulb is directional, so you might have to try it both ways round to get it to go.

You might even want to drop the guts of a superbright torch straight into your saber as a whole. Check out the mega bright torches at jaycar, they are waaaaay brighter than commercial torches. :thumbsup
 

TJack

Master Member
Community Staff
RPF PREMIUM MEMBER
Thanks for the info, I'll have to either double check the details for you when I get home or try and convince my wife to take out the bulb and tell me.

I looked at the Jaycan website, great stuff, but there is no way I can get aything in time for Friday. I know of a local electronics store here that should be able to get me whatever is needed.

I did consider just buying a small LED flashlight from a dollar store and sticking the guts in there, but again, I wasn't sure exaclty how to go about it.
 

TJack

Master Member
Community Staff
RPF PREMIUM MEMBER
Ok, so she just called and told me that the only thing she can find on the bulb is 2.4 watt max, 2.4 v05a.

I know it takes 2 AA batteries, so I'm assuming that 3v would be correct?

I called the electronics store to find out about the LED mA and all he could tell me was that they are 3.2 volts. He said that he is not able to tell me the mA or can he give me any advice on wiring it.

Does any of this help?
 

blip

Sr Member


This is what you are trying to do.

Most LED's run at about 20mA, so this means a resistor value of about 150 Ohms.

If you get the led backwards, it's ok, it won't destroy it, it just wont go till you correct the direction.
If the LED is glowing a bit on the dull side, then you can chop the value of the resistor down by 10 Ohms or so. It's not an exact thing, electronics operate in a general range and there's quite a bit of room for variation. You can get the optimal result with practice.
 

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TJack

Master Member
Community Staff
RPF PREMIUM MEMBER
Thanks, that was pretty much how I envisioned the circuit to look. So if I was using a cr2032 battery that is 3v, that would work to replace the 2 AA in your diagram, correct?

If that's the case, I have been told that a resistor is not needed for one LED running off 3v. Since I'm not an electrician, is this correct?
 

TJack

Master Member
Community Staff
RPF PREMIUM MEMBER
So I was playing around with the cr2032 and an led and it doesn't seem to light up the sabre any more than the bulb did, even though the led appears to be much brighter. Is there a way I can make it shine more?
 

blip

Sr Member
Thanks, that was pretty much how I envisioned the circuit to look. So if I was using a cr2032 battery that is 3v, that would work to replace the 2 AA in your diagram, correct?
Yes that's correct. With batteries, you can just add them up to get the total value.
:thumbsup
 

blip

Sr Member
If that's the case, I have been told that a resistor is not needed for one LED running off 3v. Since I'm not an electrician, is this correct?
The Led may have a slightly shorter life, but for your application, I see no great harm.
:thumbsup
 

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blip

Sr Member
So I was playing around with the cr2032 and an led and it doesn't seem to light up the sabre any more than the bulb did, even though the led appears to be much brighter. Is there a way I can make it shine more?
Led's aren't that bright. Advances have been made in LED technology in recent years and you can now get some Ultrabright versions. They cost a bit more.
I have a torch running one of these new ultrabrights and it makes a solid beam into the night sky.

A reflector may help.
 

blip

Sr Member
Did you want me to post a diagram on how to wire up three LED's instead of just the one? Three Led's = three times the light.
 

TJack

Master Member
Community Staff
RPF PREMIUM MEMBER
Thanks a bunch blip, you have been a great help. I'd love to set up 3 led's to get more light out of it. Will I need a third battery then too? I will only have this out for a few hours on a couple of nights so I'm sure it will last that long.

I attached pics of the current battery holder in the handle, the bulb socket and the reflector.

Will I need to make a lot of modifications? Or can I just solder the led's to the socket and put the reflector around them?http://www.therpf.com/attachment.php?attachmentid=72614&stc=1&d=1319778191http://www.therpf.com/attachment.php?attachmentid=72615&stc=1&d=1319778191http://www.therpf.com/attachment.php?attachmentid=72616&stc=1&d=1319778191
 

blip

Sr Member
Thanks a bunch blip, you have been a great help. I'd love to set up 3 led's to get more light out of it. Will I need a third battery then too?
No you won't, the battery will just get used up three times as fast.
 

blip

Sr Member
I attached pics of the current battery holder in the handle, the bulb socket and the reflector.

Will I need to make a lot of modifications? Or can I just solder the led's to..
Three leds will fit into that space ok. When I show you the layout, you will see why.

Why not break the glass on a spare bulb, remove the waste glass and glue and solder directly on to the old bulb base. That way your wife won't kill you for wrecking her gift.
 

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TJack

Master Member
Community Staff
RPF PREMIUM MEMBER
Three leds will fit into that space ok. When I show you the layout, you will see why.

Why not break the glass on a spare bulb, remove the waste glass and glue and solder directly on to the old bulb base. That way your wife won't kill you for wrecking her gift.
It never even occurred to me that I could do that - so if I break the bulb, where exactly do the wires solder to? I'm assuming the 3 bulbs wire in sequence, then one wire solders to the outer part of the base and the other to the very bottom?
 

TJack

Master Member
Community Staff
RPF PREMIUM MEMBER
Thanks again blip. So if the longer wire on the led is the +, then I connect all 3 + wires together and all 3 - ones as well. Which group will connect to the outer edge of the base and which one goes to the bottom?
 

blip

Sr Member
It's been a while and I can't remember. Maybe just touch a single led on the contacts before soldering anything. No penalty for getting it backwards, it just won't go.
 

TJack

Master Member
Community Staff
RPF PREMIUM MEMBER
This is what I love about this forum, thank you blip for the assistance. It's definitely brighter now than it was with the bulb :) The only thing I noticed is that the light seems to die off a bit at the end. When I was looking around at other lightsaber posts, I read that when you are using a tube, it's recommended to put a reflector at the tip to bounce the light back.

I'm not 100% sure how to make that work with this one since it extends when you flick your wrist (and if it would even make a difference). It doesn't look like it's very easy to get the toy to split apart so that I can access the smallest cone.
 

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