Modding lights to take LEDs

eyeeatingfish

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Apr 19, 2007
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I have looked around and seen some tutorials about moding maglights to take the new LEDs and stuff but im a little lost. Some of the parts they put in I dont get. How come you cant just sodder the wires straight to the bulb? There has to be a resistor and a heat sink?

The new CRE lights are pretty interesting and I have a few lights I wouldnt mind converting, but if i only see mod tutorials for certain flashlights then that doesnt teach me overall how it works, and how i would adapts it to other lights.

If there is already some post explaining everything i need to know then please direct me to it.
 

RustyKnee

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Apr 26, 2007
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eyeeatingfish said:
I have looked around and seen some tutorials about moding maglights to take the new LEDs and stuff but im a little lost. Some of the parts they put in I dont get. How come you cant just sodder the wires straight to the bulb? There has to be a resistor and a heat sink?

The new CRE lights are pretty interesting and I have a few lights I wouldnt mind converting, but if i only see mod tutorials for certain flashlights then that doesnt teach me overall how it works, and how i would adapts it to other lights.

If there is already some post explaining everything i need to know then please direct me to it.

Heats ink issue -
High power LEDs need a heat sink. Bulbs put out their heat as infrared out the front, LEDs don't, they get warm due to the resistance in them. this heat needs removing.


Resistor Issue -

LEDs run at lower voltages that are typical for bulbs and what the batteries supply. So the Resistor reduces the voltage seen by the LED. This is only one way to do it though. Resistors drop the excess voltage across them selves, this means that they dissipate the excess power. Another way is a regulator. 1 type of regulator acts like a resistor, but changes it resistance to control either currnt or voltage. The other type of regulator is a switching type, this doesn't waste as much power so give better run times off the same batteries. Further info on switching regulators some are designed to reduce the battery voltage, this is called buck. Others are designed to increase the battery voltage to that required by the LED, these are called Boost. some do both Buck and Boost

for your last question...not sure how to answer that apart from gain a basic knowledge of electronics...read books and the web. undersatnf ohms law and how power is calculated. read about the non linearity of LED current against voltage comparedto resistors linear nature of current and voltage. gain a basic understanding of what different forms of reguillation do (I touched on that already). For the mechanical issues, thats going to be a matter of working out how its going to fit if there is no guide already. you will need to consider reflector issues. the reflector will be designed for a particaular light source type. it may be adaptable, or you might have to change the reflector.

I don't think there is an easy answer that will teach you how to do this apart from read up and learn. The subject is too big. If you have specific questions when learning though, I am certain you will get help on here.

Stu
 
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yellow

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As rustyknee already typed, HEATSINKING is the part very much led lights suck at. You can never overbuild a sink.
Take those cheap 5mm led cluster lights at e-bay --> go through just a few sets of batts and several of them quit. Because of too much current / too much heat.

If You really want get a bit info, read this tread here:
http://candlepowerforums.com/vb/showthread.php?t=83903&highlight=guide+minimag+modding

starts with ready made upgrades but goes into self modding also.
There is not soo much of a difference with the much better actual emitters.
As sson as You got the info there, You need enough
 

eyeeatingfish

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Apr 19, 2007
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The ma issue is hard one two.
Let me ask this then, if I do something wrong and dont use the right resistor or the right heat sink am i going to blow up or ruin the flashlight or is it just not going to run at optimal efficiency?
Also, these electronic insides, resistor, regulator, etc. can you get these at the guys from radio shack and are they knowledgeable on what id need and stuff?

Ive seen the mods for maglights that look good. The ones with multiple LEDs. Does anyone sell kits that have the parts sodered together and require minimal work to put in? (Not talking about the simple drop in LED upgrades unless they have ones for CRE LEDs.)
 

bfg9000

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You can solder the wires straight to the bulb holder, and as long as you're not trying to run crazy amounts of power through the LED, using just a star base for a heatsink works fine--that's how a lot of cheapo lights like Dorcy are made from the factory.

Just take some old 3-cell light you may have lying around like this 20 year old plastic Brinkmann, that looks like a star will nearly fit in the reflector
bm.jpg

Rather than soldering to the light, I decided to make it a reversible drop-in module using this DOA Fivemega bulb that was damaged in shipping (Cheers to Fivemega for replacing it without me even asking and even though it was the postman's fault!)
fm-bulb.jpg

The purpose of the resistor or regulator is to prevent too much current from going through the LED and burning it out. Too much current can also be avoided simply by matching the correct Vf LED to the cells, like this oddball "L" high-Vf Seoul that EngrPaul sent me as a freebie (Thanks Paul!). There's no resistor in the circuit; it's purely direct drive on 3 alkalines. That's also why those low-Vf LEDs work fine in direct drive with a single Li-ion like a 18650.
close.jpg

I had to trim the star a little using metal nibblers, so that it would fit into the stock reflector (it switches on and focuses by twisting the head like a MiniMag). Probably a non-focusing light would be simpler to mod
finished.jpg

In the finished product the star does not get too hot to touch even when run continuously, which should be the case if you don't go over ~350-500mA. And that's with the star completely insulated in a plastic light and held with a dab of silicone glue.

In case the wires come adrift (it's not exactly solid state
icon12.gif
) the spare incan bulb in the tailcap may be fitted in the field.
 

eyeeatingfish

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Apr 19, 2007
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Wow, thanks BFG9000, thats more what i was talking about.
I dont want some super mutated flashlight, I just want to be able to turn my existing lights into more output while saving battery life.
Specifically I have the following flashlights
2 minimags (I bought the $10 0.5 watt drop in LEDs from teralux and these things are great for lighting up any room in my house)
3D maglite
2L and 3C streamlight twin tasks
T3 (newest edition)
TL-2(LED version) from streamlight
Princten Tec EOD (Great light, wouldnt bother modifying it)
2AAA dive light from UK(I think its UK)

The T3 i feel bad about because it uses up 3 batteries in about 2 hours. $$$$ At least with a CRE or soul the time might double, though i understand T3s are harder to mod. I dont want a 300 lumen surefire size light, i just want max runtime at say... 100 lumens.
Though i do have to say my maglite is fair fame as its jsut collecting dust.
Premade drop in upgrades are preferable.


So far ive learned this much, volts add up, two 3 volt batteries equal 6 V right?
What are the mAh though? And how do i know how much of those the batteries are putting out and how much the LEDs can take?
 

Skibane

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Nov 26, 2002
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San Antonio
Excellent post, bfg9000!

I might add that a few of the low-power white LEDs run pretty well when directly driven from just two 1.5 volts cells - no resistor required. This makes it easy to pull the bi-pin incandescent bulb out of a mini-MAG (or other similar light) and simply plug in a 5 MM LED replacement (taking care to observe correct polarity, of course). This approach won't give you blinding light, but it'll make a pair of AA alkaline cells last for many days of continuous operation. Since the LED draws well under 0.1 amps, no heat-sinking is required.

Two good low-power white LED candidates:

1. Lumex SLX-LX5093UWC/C (available from Digi-Key for about 80 cents apiece under part no. 67-1691-ND), and

2. "Super" MJ uncut 4-die LED (available from The Sandwich Shoppe for $4.50 apiece).
 

bfg9000

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Yeah there used to be a lot more interest in fun and simple "ghetto mods" over in the Homemade and Modified forum before all these imported $10 CREE lights showed up
icon12.gif
. Try searching the archives (though the useful pictures may be long gone) or Quickbeam's mod page here.

The simplest 3D Magmod would be one emitter on a premade heatsink. Any such heatsink should allow running the LED flatout at its maximum spec of 1A. There are a number of guides with instructions.

Before buying any emitter, you will want to make sure the color bin (tint), flux (brightness) and Vf (forward voltage) are okay for your application. Generally the more desirable emitters are brighter, whiter, and more expensive. If you want to use direct drive just look the Vf up on this chart. Otherwise, this resistor calculator will tell you what resistor to use with your too-low Vf LED. A more elegant solution would be a Downboy (buck) or linear regulator.

If all that sounds too complicated, you could always just buy a complete dropin module.
 

eyeeatingfish

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Apr 19, 2007
Messages
920
Is there anyone who offers a modding service? Anyone i could send my INOVA T3 to who could fix it up with a cre so i could save money on batteries?
 

vic2367

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Mar 11, 2007
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new york city
woulsd also like to know,,,have a pelican m3 led 2370 that i want the factory led out and installed with either a cree or seoul led,,,anyone ?
 
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