|
I have been thinking of making my own lights using a number of the very bright LED upgrade bulbs for the larger MAG lights that are about $19 a piece, and use a existing reflector. But I noticed that the Deepsea LED lighting unit doesn't have a reflector, just a black face. So I'll have to test that. The MAG lights use a reflector, but since they used to use a more conventional bulb, perhaps that is the reason. My biggest issue at the moment is getting the right voltage to power the lights. I'm shooting for 12 or 18 volts, so I can power the lights with the larger 18 volt Li-Ion cordless tool batteries, so I can charge them quickly and they are a separate system from the main battery banks. I suspect I might need a 24 volt to 12 volt resister, but I need to hear what you guys think is the best option. Perhaps this is a good mind puzzle for David. I know I'll loose some power in the conversion from 18 volts to 12, but at the moment the 18 volt Li-ion cordless tool batteries are much larger, usually in the range of 3 amp hours. We used fluorescent bulbs outside are six man hyperbaric chamber, next to the Hyzod polycarbonate top small windows for internal light, since they were about the coolest option at the time. I think Sean makes a very good point about reflections if the lights are used in the viewport one is looking through. Regards, Szybowski From: bottomgun@mindspring.com To: personal_submersibles@psubs.org Subject: RE: Re: [PSUBS-MAILIST] LED Lighting Options Date: Thu, 8 Jan 2009 17:03:23 -0500 As Sean alluded to, to minimize backscatter from particulate matter and plankton in the water column the optimum angle to place lighting is at a 45 degree angle to the subject from the viewer’s direction. An additional method that is useful in special applications is to place the lighting behind the viewer (but not in the sub). R/Jay
Respectfully, Jay K. Jeffries Andros Is., Bahamas
As scarce as the truth is, the supply has always been in excess of the demand. -Josh Billings
From: owner-personal_submersibles@psubs.org [mailto:owner-personal_submersibles@psubs.org] On Behalf Of Sean T. Stevenson When I think "dive light", I don't think about the little dry cell powered handhelds used by recreational divers, but rather the technical / cave diver style canister light, comprising a light head held in the hand, and a remote battery canister for power. I have owned a handful of these over the years, starting with a halogen video bulb using SLA batteries(12V), and most recently, a 50W HID setup powered by NiMH cells. Regardless of the unit, the basic setup is the same, with the bulb / arc assembly housed within a (borosilicate glass?) "test tube", and the reflector being completely independent of the bulb assembly, permitting axial movement for variable focus. The glass itself is not that thick - presumably, thick enough for the pressure, but thin enough to permit heat transfer to the surrounding water, providing conductive / convective cooling to the assembly. The HID setup is great - bright even compared to ambient daylight. If you shine a light out your viewport, I forsee a problem with reflection off the viewport back into the cabin, as well as simply being too bright, too close to your eyes to permit effective outside viewing. Also, backscatter problems are minimized when your light source is out to the side, or at any angle other than your viewing angle - using a light inside the cabin means you will get every reflection from suspended material in the water, not to mention the fact that you need another viewport for the light to keep it separated from your eyes. Also, as you noted you need a lot of light to see effectively through water, and any technology other than LED is going to produce a lot of heat that you need to cool. Consider how to get rid of it. -Sean |