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Hello all, since I got the idea in Texas, I figured I would pass this along here also- I recently had the opportunity to try out a new LED light underwater in Mexico and would like to share the results. The light is a standard 20 LED array mounted on a homemade PC board 1.5 x 1 inch. LEDs are recessed into a small block of delrin deep enough to make the tips of the LEDs just below flush with the top edge. The LEDs are soldered to the back of the board and all other connections are tinned. This is covered with a layer of silicon, more to adhere the board to the delrin than to protect the pcb. the wire is two conductor 24 gauge speaker wire run to an old gutted Petzl DUO battery box. The whole thing runs on 3 AA's providing 8 hours of good strong "walking" light and another 8 hours of "crawling or climbing" light. It continued to burn for two more days, but the color changes, and the light is no more than a weak backup after the first 16 or so hours. I intentionally did not provide the LED's with a housing, as I wanted to see how they would work exposed to elevated pressure (no problem at all) and how well the system would work with as little protection as possible. The only damage was a little water in the battery pack, due to the poor design of the case and the fact that it is well cave worn and 5 years old with the same gasket. It did not totally flood until about 100 feet. I did manage to knock out an LED a couple of days later due to direct impact while crawling. It just popped out, most likely because the square base was mounted flush with the PCB and any lateral movement was too much for the tiny connector wires. However, because the leads were connected into a continuous tinned etching, it did not affect the rest of the system. There was no corrosion on the PCB once disassembled, after a week of heavy mexico caving and a number of days in the water. Because of the exposed design, mud is easily cleaned off the LEDs and pcb with a stiff toothbrush. The light underwater was not similar to any other dive light that is currently on the market. The high temperature color is very close to the new HID systems, which is the key to its effectiveness. Unfortunately there is no beam to speak of, only a very diffuse, bright glow. Each of the LED's has an internal reflector which focuses the light to a 20 degree beam. The beam is evident when someone flashes you directly in the eyes, but it is just not focused enough as an array to make a tight beam for signalling. I certainly would not recommend this for team diving, as there is just no way to signal with this light. For solo sump work it is more than adequate. I have had the chance to test it in a few different environments, In Mexico the water was 120 foot viz, blue in color and without any suspended sediment, white cave walls. In this environment, the light was easily equivalent to a 20 watt halogen. I also tried it in Florida in a few different places, in dark water/dark walls the beam is almost non-usable; it seems to drop off much faster than halogen. In greenish water with white walls, the results are similar. It actually works better than halogen in low viz regardless of water color, creating a much more usable light due to the type of beam and color. The cost to me for my entire light was less than 55 dollars, of course i was using an old battery case. There is no reason one could not substitute a nice piece of PVC for a battery case that would be just as adequate, ala Terry Holsinger's setup. The big advantage is size and weight. Mounted on the helmet is never the best solution for in the water, but if you use if for dry caving too, this light is by far the lightest weight light available for the amount of light and burn time. It could always be rigged so that it would come off the helmet, and is much lighter and smaller than any of the hand held dive light solutions. I will try to get some digital pictures up for those that are interested. If you live in Texas, ask Terry Holsinger to see his helmet light, it is basically the same rig with a larger battery pack. jason Jason Richards NSS-CDS 41539
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