How to modify a Maglite to Run on LEDs
 

I have been wanting to do this mod for some time and wrote it up for another site where I post sometimes. Thought I would share it here too. I wanted to make a maglite that runs off of Bright LEDs. They use way less wattage than regular maglite bulbs and should run for 5x longer with the same batteries. They also SHOULD be brighter than a regualr bulb.

I actually did this with a 2AA MiniMag Lite and just stuck the LED into the holes, but I was unsatisfied with the results. As such I decided to use my 3D cell MagLite instead. Here is the victim:
http://users.adelphia.net/~dhartensveld/flash_1.jpg

Since 3D cells produce 4.5 Volts and LEDs I choose operate at 3.6 Volts, I decided to wire 3 LEDs in parallel with a 12 Ohm resister. I used a ¼ watt, 5% tolerance resister and calculated it’s need using this tool: http://metku.net/index.html?sect=vie...calc/index_eng
http://users.adelphia.net/~dhartensveld/flash_2.jpg

First step was to remove the lens cap to get access to the bulb on the MagLite.
http://users.adelphia.net/~dhartensveld/flash_3.jpg

Then I unscrewed the cowl that holds the bulb in place and removed the Bulb.
http://users.adelphia.net/~dhartensveld/flash_4.jpg

http://users.adelphia.net/~dhartensveld/flash_5.jpg

This is when I remembered that I USED to be good at soldering. Other than small things here and there, I am about 12 years out of practice. I will get better one of these days.
http://users.adelphia.net/~dhartensveld/flash_6.jpg

I got my LEDs from http://www.lsdiodes.com/. Seems like other folks from this site like them so I used them too. They came in one day even though I used regular shipping. Not too shabby. I choose the 5mm 12,000 mcd White bulbs as the brightest ones I could find.
http://users.adelphia.net/~dhartensveld/flash_7.jpg

This is where it gets interesting. I want to reuse the bulb so I can swap out an actual bulb with my LED cluster if I have to. As such the resister has to fit within the cowl and bulb area. After soldering a lead to the end, I hot-glued the resister under LED #1. Please note, I would wait to hot glue anything until after the soldering is done. The soldering iron can heat up the glue when soldering nearby and make a mess.
http://users.adelphia.net/~dhartensveld/flash_8.jpg

Looking good – ha ha my soldering should be a crime.
http://users.adelphia.net/~dhartensveld/flash_9.jpg

Ok – so I smashed the bulb and was surprised to see the leads still intact after I removed the little blue thing that I think was a resister and the filament. I was going to dig this whole thing out and solder to the casing, but instead, I soldered to the leads. As you know, it is crucial that you get your + and – correct or your LEDs won’t work (remember these are not just pretty lights folks – they are Diodes which only let current flow in one direction. Hook them up backwards and you are in the dark). You figure it is a 50/50 shot here, but I choose the lead closest to the side of the bulb where the notch was as negative. You can’t see it here, but there is a small dab of solder there where the lead is connected to the housing. I figured the one closest to this spot would be the negative and I was right. Not sure if this is standard, but it might be.
http://users.adelphia.net/~dhartensveld/flash_10.jpg

I stuffed the lights through the cowl and it is all hooked up and ready to plug back in a screw into place.
http://users.adelphia.net/~dhartensveld/flash_11.jpg

All hooked up and in place - /me crosses fingers……
http://users.adelphia.net/~dhartensveld/flash_14.jpg

Success!
http://users.adelphia.net/~dhartensveld/flash_12.jpg

http://users.adelphia.net/~dhartensveld/flash_15.jpg

Couple of thoughts:

I thought this would be brighter than it is. I am not really disappointed with the light output I am getting, I just thought it would be more. Maybe someone can give me some advice on what I could have done. There are a couple areas that may affect this.

I used my Dremel to “frost” the LEDs to see if I could get some more diffusion. They are pretty pointed in how the light comes out and they don’t take advantage of the mirror lens. It helped some, but not a lot.

Another thing, I used ¼ watt resisters and I am unsure if I should have used a lower value or what effect that would have. I don’t really know how to adjust that.

It should be getting exactly 3.6 Volts based on my resister. I am not sure what would happen if I gave it more or how much it could take. I should have bread-boarded this thing first to test, but I don’t have a convenient power supply (read: Lazy). I wish I could see how much brighter they would be with a little more juice.

Let me know what you think or any ideas.

Here is a site with alot of flash light mods you may get some ideas from. www.candlepowerforums.com

thats pretty cool... you able to take a picture comparing a modified and non modified one?

Holy crap - I had no idea. This looks to be the beginning of a serious problem....THANKS FOR THE LINK!!!!

Yeah - I can do that pretty easy since the bulb swaps out the way I designed it with the LED Cluster. I don't know how well it will show up though in comparison.

How much more expensive is it really to buy an LED penlight?

WHat you did was cool as hell, but Im wondering if its really worth the effort...

Wow there really is a forum for every subject on the internet!

Well, I learned in the process and had some fun thinking about it so, yes it was worth it.

I imagine a LED penlight might be cheap, but this is a 3D cell maglight! Bigger is better (an incedentally brighter)

Fair enough man, I know those LED lights arnt cheap.

Have you tryed the luxeon leds yet?
http://www.lumileds.com/products/

changing the resistor shouldnt have any effect on the brightness, nor the amount of current passed to the diodes should have any effect... you might want to change the LED color, if those are clear as they appear they are the most under developed LED so far, you will get more brightness with maybe a blue

Your problem is probably the reflector. The maglite reflector is specifically designed for max light output using the maglite-specified bulbs. You've now completely changed the way the light source emits light, and have completely changed the pattern of that light emission, but you haven't done anything to modify the reflector.

If I were doing this, and just felt like getting it as right as possible, I'd go buy a Surefire E2 and see how they do it.

That is a pretty cool mod.
I went to that candle power site and didnt understand a damn word of what they were saying :D