Hi guys,
Wayne Y. beefed up the BB some time ago so it could handle higher than typical flashlight voltages. As I recall, it was for the Shark LED project. Although I was aware of this, I have been too involved in the Aleph series and other single die applications to find the time to take advantage of it. The 3x5mm was the first chance I got and it provided a little more incentive to try to get to this idea. There is also the question of real estate. This light has a 2.5" diameter head and yet the photon management is done with a reflector that is less than 1" in diameter. I went to do this mod over a month ago but when I looked at all of the wasted space with the 4x 20 mm reflectors, I decided that I wouldn't do this unless I stuck some additional LED's in there to justify the over all size of the head. That additional self imposed requirement was enough to put the parts back on the shelf for another day.
Another significant change in the BB that allowed me to go with this is the fact that the BB will not go into instant death if the output is "open" or there is no load. I have no idea if the SPST toggle switch I used has an instant of no load when it is switched but it doesn't matter.
There is one consideration that I failed to recall and it almost resulted in this mod being an exercise in futility! /ubbthreads/images/graemlins/icon15.gif At one point yesterday, after final asembly of what had been working flawlessly up to that point, I found that the light would not work! Just a dim glow from the LED's on either circuit. /ubbthreads/images/graemlins/banghead.gif The BB has a common ground so isolation of the LED slugs was not needed (all 8 of them). However, wiring the LED's in series is a problem that has been mentioned in the past and one that I failed to recall! As it turned out, I was able to save this mod by isolating the E-can from the pedestal by taking the thing apart and machining a delrin joint or coupling that joins the E-can and pedestal. I still had my doubts because the M4 battery tube has chem film on its threads and I was depending on the HA of the threads in the turbo head to isolate the ground path. Fortunately it did! I have seen anodized heat sinks criticized because the anodize film is a poor thermal conductor. Well Lumileds in their infinite wisdom has designed the Luxeon so that the slug requires electrical isolation but the best thermal conductivity available; most material choices are at odds here. After this near failure, I am opting for anodized sinks from now on, regardless! WIth some recent designs from scratch, I have become acutely aware of the head and batery tube as a means of either providing or isolating the ground path and I have been trying to make my designs viable whether the head and power pack are electrically conductive or not. In the case of the battery tube being used as the ground conductor, there are obvious limitations and considerations.
I played with this light late last night (actually this morning) and it does what we would wish the L4 would do! Talk about a wall of light! At 20' with the flood group on in high, there is no evident beam; just light everywhere in front of the head. If you need to reach out further, twist the ring to the columated group and you have a strong spill illuminating the foreground and a very useful hot spot that gets out there. I like the irony of taking a turbohead that was designed specifically for throw and using it to host a package that is opptimal for the other side of the coin! /ubbthreads/images/graemlins/grin.gif
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