The SBT90.2 should have a bit higher surface brightness than the dedomed XM-L2, but I expect also a bit better optical performance from this lens, and also the larger surface area of the die may be a bit more forgiving for the poor quality of fresnel lenses. But there is a lot of guessing involved, my fuzzy conclusion is 2Mcd but it can go either way.
The output of the SBT90.2 is also much higher as the dedomed XM-L2, about 4 times, but with the smaller lens at increased distance, the amount of light exiting the lamp will not that much higher.
After a lot of measuring (the heatsink must be centered pretty perfectly on the alu plate to get the led centered behind the lens) I made some holes in the 20cm x 20cm x 3mm aluminium plate, 4mm small holes with a drill and two bigger holes with a fretsaw (IMO the fretsaw is the ultimate handbuild tool )
Do I recognize an Amutorch Yootoo SD2? Very interested how that plan is coming together.
FWIW, I do remember a sketch of a big thrower with the batteries placed behind/around the reflector.
Yes, an SD2, I have two of them spare because they did not fit the boost driver I was planning to mod them with
Now it is a convenient 21700 battery compartment with added switch.
And yes, this is still my favorite setup for a big thrower since the first plans for the BLF-GT. Who knows it will be picked up some day by a manufacturer.
No, they do not know that I build searchlights. But they do know that I build stuff myself every now and then, before summer I built a wind tunnel from wood and polycarbonate panels for physics demonstrations (to make wind I used a 10 inch 12V 80W car radiator fan from aliexpress).
Yes, two pieces glued together, I think that I will glue the lens in the slot from the outside after everything else is finished, and keep the lens clean. In fact I have two identical fresnel lenses (they are cheap), one for during the build to check the workings, and one for the finished lamp.
To check the potential of the lens, I clamped it in with a FT03-mini (harddriven SST-40 with dome) behind it. I measured the throw at 6.99 meter from the fresnel lens and got 2.16 Mcd (at 30 seconds). So the potential is there, the domeless SBT90.2 should even do a bit better, and if it doesn’t I can always go SST-40 and have the runtime and less heat.
That is fun indeed!
I admire your creativity and work! An SBT will blow it, not in the “explosive” way! You’ll soon rename your city to Amster…daaaamn :o when that beam hits the sky
Thanks Martin, and others. The creativity was already 4 years ago, it is more of a rebuild with improvements based on what I learned back then. I like that you do not need to be a fancy flashlight manufacturer to make a superthrower, this thing will look extremely homebuilt . But I must admit that the cost of the parts add up, I’m over 100 dollar already, the led+board+heatsink+alu plate+SD2 were 92 dollar, I can’t remember the cost of the lens, but it was about 10 dollar. Maybe 8 dollar worth of plywood, and a dollar for a handle, so maybe 120 dollar. That is what I paid for the Lumintop/BLF GT a year ago so homebuilding is fun but does not really pay off :person_facepalming: