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LED flashlight from scratch

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  • LED flashlight from scratch

    Hey all, I've been playing around with making some LED flashlights. Here are a few pics. This one uses an 18650 type rechargeable li-ion battery. I decided to get a little crazy and make a charging stand as well so I don't have to remove the battery from the light.





    Here is a shot of the Cree MC-E LED. I'm using an aspheric lens instead of a reflector. The 4 die LED makes kind of a weird square pattern when used with the aspheric, but it's actually growing on me.




  • #2
    Very nice work. If you feel the urge, I'd love some more detail so I could attempt to make one myself.
    James Kilroy

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    • #3
      Nice looking flashlight. Making and modding flashlight is a big hobby for some. With the ultra high power LEDs now available it is easily possible to make flashlights that could be considered weapons. I wonder how long it will take for the authorities to catch on to that?

      The current brightest LED from DX is a 100 watt array that puts out 8000 lumens from one square inch. If that amount of light is focused to maintain a spot size of perhaps 10 square inches at a distance of a couple of metres then the intensity at that distance is about 10 times brighter than the sun.
      Free software for calculating bolt circles and similar: Click Here

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      • #4
        Evan, that sounds like fun. Now I just need to fit that into a handheld

        Some more specs:

        battery- 18650 (2600mah) from batteryspace with an additional PCM protection circuit board that prevents over charge/discharge (from BS as well)

        LED-Cree MC-E...forgot where from but they are readily available. It's supposed to put out 750 lumens at 2.8 amps.

        Driver board- 3 mode, low/med/high 2.5A max from shiningbeam

        optics-there is an insane amount of optics out there but this particular build uses a 21.5mm plastic aspheric lens from dealextreme

        That's the main stuff. The rest is just machining

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        • #5
          Originally posted by Evan
          The current brightest LED from DX is a 100 watt array that puts out 8000 lumens from one square inch. If that amount of light is focused to maintain a spot size of perhaps 10 square inches at a distance of a couple of metres then the intensity at that distance is about 10 times brighter than the sun.
          Shades of Tom Clancy's wepon used by the Clark/Chavez team. :-)
          ...lew...

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          • #6
            That looks both fun and useful. How hot does the head get when left on hi for a while? I suppose you'd have cut fins on it if it were a problem, eh?
            Southwest Utah

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            • #7
              At 2.5 amps the head gets fairly hot but the brass is good at moving the heat. At normal room temperature it never gets too hot to touch, but it might keep you from freezing to death in a winter storm...although only for an hour or so It's about maxed out in terms of ability to dissipate heat, but yeah, fins might help. Not strictly "necessary" in this form factor.

              Run time is about 60 minutes on full throttle. Medium is something like 1A and that will last for 2.5 hours and low is 140ma...and that will last forever.

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              • #8
                Nice job. It's a twisty? I did not see a switch. It looks to be about 5 inches long, nice for a coat pocket.

                If you find that the LED burns out early, try using aluminum next time. It conducts heat MUCH better than the brass does.

                Dan
                At the end of the project, there is a profound difference between spare parts and left over parts.

                Location: SF East Bay.

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                • #9
                  I also like the o-ring trim. Have you considered a version with a squared off head? Maybe a triangle or double flats etc to keep it from rolling? You could still use the o-rings.
                  Southwest Utah

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                  • #10
                    For a real touch of class make the head from silver. For the last word mount the emitter on a diamond wafer heat spreader. Diamond conducts heat 5 times better than silver.
                    Free software for calculating bolt circles and similar: Click Here

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                    • #11
                      How did you choose the focal length of the lens and etc?

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                      • #12
                        Any all all suggestions welcome! I'm going to be making some different versions of this, so it will be fun to have some different things to try out for the shape and detailing. Evan, you are speaking my language. I've always wanted a 45 thousand dollar flashlight

                        As far as the shape, I had no plan, or drawings for that matter. I just grabbed some scrap and went for it. I'm not awfully worried about the thermal dissipation (in terms of brass) but you are correct, aluminum would be better. I like the brass though. It gives it some heft and I think it looks swanky.

                        Oh, and yes, it's 5.25" long. I'm impressed that you can tell! It's a twisty as well. My latest version actually has a tailcap switch instead of the charging port. Just trying some stuff out. I have to say, I like the switch better than the twisty. I suppose the next challenge is to integrate the switch and "stand up" charging.

                        On the optic, I guessed. I made a little clip so I could hold the LED on bench while it was connected to a power supply. Then I started stacking o-rings on top of the led and then sat the lens on top. I found that "3 o-rings" gave me the right out-of-focus condition I was looking for. So I bored the head that deep and made a little delrin stand off that fits over/around the LED to hold the lens at the right distance.

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                        • #13
                          Nice thread... I have a minimag LED torch, takes 3XAA batteries but died after only 8 months.... Can't get spare parts but the holder is too good to throw away....

                          I need to mod it somehow

                          BTW why are they called flashlights and not the more correct torch?
                          Precision takes time.

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                          • #14
                            Originally posted by .RC.

                            BTW why are they called flashlights and not the more correct torch?
                            Do you also call underwear "pants" and cookies "biscuits"?

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                            • #15
                              And why do you park on a driveway, and drive on a parkway?

                              And it's a good question- why are they called flashlights? None of mine flash, they just turn on or off. And torch- why would they be called torches? None of mine burn anything. Although Evans idea would come pretty close- imagine focusing that 100 watter to 5 sq inches, that's 40 suns worth of spot brightness. Focus it closer, make it 1 sq inch- that's 1000 suns. I never thought we'd be able to burn ants with leds-
                              darryl
                              Senior Member
                              Last edited by darryl; 11-11-2010, 01:23 AM.
                              I seldom do anything within the scope of logical reason and calculated cost/benefit, etc- I'm following my passion-

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