There is probably less demand because high powered stuff outside the visible spectrum can be horribly dangerous. We have some at work that will absolutely burn your eyes out. They are even described in terms of “scalable, non-lethal use of force”.
But I just want to illuminate without giving off visible light. 850nm is right on the border of being undetectable. I will check out the links you sent, and see what I can do. I bet I will still need to put a <900nm filter on there, Otherwise there will be a red glow at the source. My current IR floods all have that, so they are somewhat visible. This is the filter I have experience with- https://www.botach.com/maxa-beam-900nm-fully-covert-infrared-filter/. Sort of pricey.
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Don’t forget that it’s battery powered, though. Current-limiting DC converters are not so easy to find. Particularly at, what, 20A or so?
A transistor current sink using a high-power n-channel MOSFET would probably be the way to go.
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If I were to guess (which I am. One out of ass explanation pulled). I would say that the incandescent light would have a wider spectrum of wavelengths with less chance of it all just bouncing off one layer of the water than the LED. (Remember don’t know just whistling in the dark.)
He’s using a standard 100W module that consists of 10 strings of 10 LEDs in series. Constant current boost and/or buck power supplies are cheap and readily available on ebay and aliexpress and can be bought purpose built for this type of LED module or with adjustable trim pots to handle a wide range of modules. And by cheap, they’re about $5 - $10 per module. Slightly more than the high current one ohm resistors he’s using but significantly less than the LED modules.
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Well, you’re not wrong… https://www.newegg.com/Product/Product.aspx?Item=9SIAAZM4K94977
The lighting market must have changed what’s available since I last looked at this kind of gear. Still, I doubt I would go switch-mode for this application. Is there a reason to?
For the reasons I listed above:
- significantly less wasted energy
- still works even when the battery isn’t at full power
- and as a bonus most constant current LED drivers include a PWM dimmer switch
Pricey indeed. Unfortunately, it looks like trying to get LEDs that don’t need filtering also bumps the price. All the gigantic and cheap modules are 850 or close(and don’t necessarily treat their spec sheet as anything other than a suggestion). If you head toward 940-950 you can still get individual emitters in the ~3w range; but prices as much as double compared to the same vendor’s otherwise equivalent part at 850; in some cases there isn’t an equivalent part because you can only get lower power.
Probably a cool semiconductor physics lesson behind this; but I’m afraid I don’t know what it is.
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A worthy sucessor to the galvanic lucifer.
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The approach that I’m talking about is to use a circuit like this one: http://www.instructables.com/id/Power-LED-s---simplest-light-with-constant-current/ Except, scaled up to higher power.
Are you really sure it would have lower efficiency? Compared to using a switching converter? I’m not trying to be argumentative. I would be interested to analyze the two circuits. I’m not claiming to be such an expert that I would know for sure off the bat.
Back of the envelope calculation says that if Rds(on) of the MOSFET is 0.05 ohms then you only lose 20W there, so efficiency of maybe 97%?
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Obligatory xkcd https://xkcd.com/1603/
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I was about to post about the Galvanic Lucifer, but figured someone might have already. 
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