I am about to order some parts to try my hand at DIY LED lights, but before I do, I thought I’d post to learn from others. I want to build cheap high-powered LED dive lights for both the normal light spectrum as well as specifically to excite fluorescence underwater. “Cheap” here means recycling some obsolete dive lights I own, with incandescent / halogen bulbs but useable shells. It occurs to me that the original Princeton Tec 400 is a good candidate for this conversion because it is made for a medium size reflector (about 52mm), has a mechanical switch that can be modified to work, and has the capacity for two 18650 lithium-ion batteries, which gives the possibilities for 3.7 or 7.4v (parallel or series).
This 52.7mm diameter module (LED, reflector, driver board) puts out >1000 lumens, and includes a regulator board to handle a lot of current:
If that is TOO bright, here's one that is a little less bright (800 lumens), a little cheaper, but much the same thing with less bright LEDs:
Both are brighter than I want unless used with a multi-mode board to allow dimmer settings, but for a UV light, I see potential to use them at the high setting.
To make a light to activate fluorescence, rather than put a filter over a light designed for white light, it looks to me like either one of those modules might be pulled apart to solder in 5 DIFFERENT LEDs that are easily sourced (Newark, Digikey) and would cover a spectrum: 365nm UV, 395-405nm UV, and then three more (purple, blue, green) to cover the rest of the spectrum that activates fluorescence. Carry one light, make everything glow that can! I haven't seen anyone do it, but it seems like a good idea. It would be fairly easy to tape over one or more LEDs to see which is doing what... To make this work with the 5 LEDs in parallel, would require LEDs with similar voltage and current parameters, and adding up to operate in the correct range for the regulator board, but this does not seem overly difficult. I would figure on buying one, measuring current output from the board, and then spec’ing the LEDs based on that.
Another alternative: I have another old light, a Sabrelight that used 3 C cells, so it too could be modified to hold two 18650 batteries. If the batteries were hooked up in parallel, and if I can modify to work with a spring-loaded contact switch that turns on with a couple of twists, it could power this UV module:
I'm pretty sure that they have a typo, and mean 390 - 405 for the wavelength, not 390-450.
And then on the smallest easiest end of the spectrum, I found I can make an instant UV dive light by using an ancient Tekna light as a shell to hold an entire UV light powered by 3 AAA’s, with just some foam in the bottom to hold it against the front!
I hope to learn from others on this before I order more parts. I got my feet wet on this DIY LED stuff by ordering a CREE XML LED and 2800ma current regulator board. I put it together with a heatsink in a big light (not a dive light) with a sealed lead-acid battery, and it works fine. Soldering SMDs on a tiny board is a challenge, but it's something I can manage a bit.
tubinoMember Since 01 Oct 2006
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