Project Gemini: Yet another headlamp mod. Not a cheapo this time though.

Flashlight Modding and DIY Parts
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I’m always on the lookout for good dual LED headlamp hosts for my projects. Those bikelight “headlamps” are just too bulky for climbers, we want slim and small, so I’ve never found a suitable metal host… until now… I saw a post on a caving forum that got me interested in the Fenix HP25R. Dual LED (spot and flood), dual switch, slim metal host… I just had to order one:

Because it’s a $80 light I did the mandatory stock test, didn’t like the UI (no individual control of LEDs) then ripped it apart. First things first, I needed to design a dedicated driver for it, so I took the measurements and got it pretty much spot on. I put in 8 x 7135s per LED and a FET for the spot LED (it’s double sided):

My previous attempt at a spot/thrower and flood headlamp failed miserably as I couldn’t help myself in putting an MT-G2 into it (Mod/build: MT-G2 & dual Nichia 219C headlamp). I was determined to do better this time… But when I saw the diameter of the spot lens I had to test fit a quad… And it fits almost perfectlyt! How can I NOT make a quad of this? Impossible!

I filled the lens holder up with copper washers and thermal adhesive, and some thermal grease for the quad MCPCB:

Everything is a snug fit. The 10mm flood LED MCPCB has a nice retaining ring too. The battery pack and cable are very decent too, no need to replace the wiring. Definitely a mod friendly headlamp host:

Driver is a good fit, and wiring it up it all fits inside:

With a high drain cell it produces some serious output for a headlamp… but in regards to making a spot and flood headlamp I’ve just racked up yet another failure… But once again I just could not help myself. How could I not make a quad with such a perfect fit? This light was simply meant to be a quad. I’ll just have to order another and try again.

I have some work to do in regards to firmware as I haven’t had dual LEDs and dual momentary switches before. Right now I’ve just got the basic functionality working, but with 16KB flash memory and two switches I think I can do pretty much anything I want.

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That’s pretty slick, Mike. Especially the new mainboard :+1:

Very nice mod :beer:

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I like the build quality of that light.

Awesome job on the board and integrating the quad. I really love what you have done.

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True BLF spirit!

Nice mod!

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Thanks for the comments all :slight_smile:

Besides the firmware I have a bit more work to do, I just received a nice XM-L2 reflowed on to a 10mm MCPCB, courtesy of djozz, and also a bare 10mm sinkpad from Lexel (thanks guys :beer: ). I’m going to open up the flood lens a little and attempt to install it further in as the current flooder isn’t floody enough. Us climbers basically want mule lights as flooders so we don’t have to point our heads at our feet when we need to find foot placements.

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Very nice mod! I thought that the 10mm board was for the plastic one, but this is a much more chique destination. I hope that the tint of the XM-L2 is suitable (it is some neutral and looks good but I have no idea which exact tint bin it is)

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Thanks! That plastic one wouldn’t warrant anyone sending anything… yet still I put a 20mm MT-G2 and two 16mm 219Cs in it :question: For my purposes it’s a pretty useless light… I love it :smiley:

I’ve fired up your LED and the tint is indeed very nice. It’ll suite nicely with the quad XP-L HIs. I just have to think about what I’ll do to the flood lens before I start hacking it up, I don’t want to ruin it completely.

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I like!

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Very nice mod can’t wait to see how the to firmware ends up

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Very nice mod can’t wait to see how the firmware ends up

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Very nice build
Humorous text.

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Orsm. I’ll be around later for a lesson in electronics. Hows your patience? :slight_smile:

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very interesting mod with sheer endless possibilities. excellent craftsmanship as well.

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Awesome work bro!

Next time put some inductors in there. The other day I desoldered an R60 from an old motherboard, just for fun. Amazing is how much current these can handle!

I mean, if there's space available, going buck/boost and full regulation is the way to go I believe.

Cheers a lot ^:)

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For you, no problems with patience at all! However, my knowledge level is pretty low so it won’t be a very long lesson :slight_smile:

I really would like to do that but my level of electronics is too low. I honestly don’t know enough to be able to design circuits like that. I read the datasheets of different ICs and most of it is lost on me. I’ve got my own 17mm boost driver on the way but the boost circuit is not my design at all, it’s a rip off from loneoceans GXB20 schematics (looks he has disappeared before sharing his newer GXB17 design, and he is not responding to emails).

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Well Mike C, if truly interested: Buck and Boost Drivers, Testing, Modding, and Discussion (Pic Heavy)

Cheers ^:)

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Very cool headlight build. I love how you can build your own custom driver, even these odd shaped ones. That opens the door to many more potential modding hosts.

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I am interested, and I am subscribed to that thread too. But once again you seem to be overestimating my knowledge in electronics. I don’t have the know-how to buy boost/buck ICs and start experimenting, I basically need a tried and tested schematic handed to me, and I haven’t seen any around besides the GXB20 (which I’m somewhat reluctant to describe as tried and tested) and some discussions in Russian on another forum.

Thanks. I’ve done a custom headlamp driver once before, but it was a much crappier light: ” Build: Dual XP-L headlight project”:Build: Dual XP-L headlight project.