Hi everyone, I have just now joined the forums but they have been a source of knowledge and inspiration in the past. I became sort of obsessed with building this LED thrower.
A short focal length lens collects most of the light from the LED and the large fresnel lens focuses it far away. The LED is actually inside the focal length of the small lens, creating a virtual image that the large lens sees. The large fresnel lens is 13" in diameter.
The power source is two 18650 Li-ion batteries on the backside. The voltage is regulated and adjustable by turning the blue potentiometer. The voltage regulator is one made by fujitsu that I got from mouser.com. Its max output current is 8A.
Further away, the LED appears to fill the entire lens.
That tower is about 250 meters away. The current was about 5A in these pictures. I don't really have a good spot nearby to do beamshots, but I was able to illuminate a tower about 900 meters away before.
Thanks for looking.