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LED Flashlights
Daniel Rutter writes: "LED flashlights are better than incandescent, but not for the reasons you might think. I've done a couple of hefty LED flashlight comparisons, now. The latest one, just finished, is here. It covers the neat little Streamlight Stylus 3, five Tektite lights (four of which are waterproof to 1000 feet...), and a couple of old-fashioned filament-bulb Maglites, so you can see how the new technology stacks up. My first comparison is here; it covers a few of LEDCorp's cheap but tough lights, and some of the very, very Star-Trekky EternaLights. They've got microprocessor control, baby!" Nifty. Birthday presents galore.
And an infra-red model, which may come in handy for those among us whose hobbies include telling something to put the lotion in the basket or it'll get the hose again.
What the hell is he talking about?
A friend of mine has made several flashlights out of LEDs, potentiometers (as dimmers), and short lengths of PVC.
Good idea but I would suggest building a small CMOS oscillator or using a 12C509 PIC and Pulse Width Modulate (PWM) the LED instead of burning up the excess energy in a potentiometer. The batter(y|ies) will last much longer.
The "Police Brutality Edition"?
LOL!
--
Use 'slashdot stuff' in the subject line in any email you send me if you want to get past the spam filter.
Yup. To elucidate further, the serial killer "Buffalo Bill" used IR goggles to see in the dark, so the reviewer must think he needed an IR flashlight.
At one point in the movie (though he's not using the IR goggles at this point), he has a victim he's holding prisoner in his house. She's being held in what appears to be a dry well dug in the cellar. He's starving her so her skin will loosen, and he wants her to put lotion on her skin to keep it from drying out. He lowers a basket into the well with a rope, and tells the girl to apply the lotion. But instead of speaking to her directly, he speaks in the 3rd person and refers to her as "it":
This is what the reviewer was referring to, though it was pretty obscure and I didn't get it until reading the previous post.
--Jim
http://www.google.com/search?q=cache:http%3A%2F%2F www%2Edansdata%2Ecom%2Fledlights%2Ehtm
Stupid job ads, weird spam, occasional insight at
A friend of mine has made several flashlights out of LEDs, potentiometers (as dimmers), and short lengths of PVC. They're great for providing very low levels of light during star watching parties; you can read maps, tweak screws, etc., without destroying your night vision (or that of the people around you). Some people prefer red (lowest energy wavelength); some prefer green (dim light goes further).
Stupid job ads, weird spam, occasional insight at
is in diving magazines. Apparently they are really good for diving (good under high pressure, very low chance of burnout, basically impossible).
You can whack them around and not get burned out.... which is rather important when you're a hundred feet under water in the dark.
Isn't this covered in some scientific urban legends page?
IIRC, the reason red light doesn't disturb night vision isn't because it's the "lowest energy wavelength," it's because the color receptors contain organic dyes that only respond to a band of frequencies. If the photon is out of that range, too low *or* too high, the receptor won't fire.
Red is outside of the frequency range of two dyes, and on the edge of the third. (If it weren't, we would see infrared and call *it* "red"). With high intensity red light those cells still fire, and other psychological changes would cause the (brain? eye?) to respond mostly with the color receptors. But with a dim red light the dye-free receptors dominate and there's no loss of night vision.
For every complex problem there is an answer that is clear, simple, and wrong. -- H L Mencken
An important safety tip about LED flashlights, learned through experience.
If you're driving in an unfamiliar area, e.g., the Olympic Penisula, and pull over to the side of the road to figure out where everything else is (since you know exactly where you are, so many miles south of the National Park on the only major street in the area), do NOT use a red LED flashlight.
It makes major roads disappear from the map.
I got *very* confused, since I knew I had driven on some of those missing roads just days earlier. I swear I started to hear the music from the _Twilight Zone_. But turning on the overhead lights revealed the missing road. Red lines illuminated by a red light disappear, and presumably the same thing happens with the other colors as well.
For every complex problem there is an answer that is clear, simple, and wrong. -- H L Mencken
When I fly, I tend to use a white LED Photon Micro light to read the multi-colored charts. Its not too bright and I haven't replaced its battery yet after 3 years.
I also carry a Eveready 2AA light with lith Lithium batteries. Its light and very bright. It will light up reflectors at over a 1.5 miles. I also carry a one that has normal Alkaline batteries if I need a semi-bright light.
I've given up on the mag light junk. Sure the case is strong but any little bump and the light bulbs go out. You can't hold them in your teeth (sometimes you need to do that in a small plane). I'm not impressed with their switches and if you have a problem, you can't fix them in the dark. Once they get wet inside, they die. Other than use as weapon, I can't see any good. I have had several maglights and they all failed. The plastic everready is something like 10 years old.
For Diving, I like the Underwater Kenetics 4D cell model and have an 8 AA dual circut light bade by Technisub. Most dive lights use magnetic reed switches so they are completely sealed but if they don't have transistor switches, you burn out the reeds but if you have transistors, they are never off.
Out in the bush, the photon is great. It is easy to carry around (just clip to to your shirt) and it lights up about a 1m circle in complete darkness. Its not too bright so you don't lose your night vision.
I have several "photon lights" (which are just bright LED lights), but I don't use them for illumination as for dancing, particularly in rave clubs, which I would suspect is the most common current use for these things.
The blue is by far the brightest. The red is OK, but the white is disappointingly dim. Now if they could just have a purple one that didn't explode on first touch of current... it would be hopelessly dim but quite pretty :)
Zaphod B
Zaphod B
When duplication is outlawed, only outlaws will have
I'm gonna order me some dry ice and overclock the hell out of my flashlight!
Woohoo!
Somebody asked above how well LED flashlights work. Mine is blindingly bright: looking into the beam at close range produces a dazzle effect like a flashbulb, complete with sparkly afterglow. I used highly-focused LEDs: it makes a beam about 2 feet across at a distance of 10 feet. Unfortunately, since the human eye isn't very sensitive to red, the beam doesn't appear very bright, but it's plenty good enough to see with at night. Battery life is very good: I gave up trying to run it down after 24 hours, although there was noticeable dimming by that point. One good thing about LEDs is that they simply grow dimmer as the battery runs down, unlike incandescents which have a tendency not to glow at all once the voltage falls below a critical point.
-- ;-)
Kuro5hin.org: where the good times never end.
A reason that LED lamps are great that is often not mentioned is that they have a very uniform illumination pattern. This is great for reading books in the tent, maps, etc. Most incandescent bulbs simply cannot focus as cleanly. Mine's quite adequate for what I use it for (see my review of the Princeton Tec Matrix on http://www.outdoorreview.com/reviews/Headlamps/pro duct_2333.asp) and it runs around 40 hours on 2 AA's. I never use my Petzl Micro or Zoom these days (anybody want them cheap?)
Dara
take a look at this page especially this graph. LED's surpassed incandescents long ago in terms of efficiency, the only hurdle left is to increase the brightness. When Nick Holonyak (inventor of the LED) won the Japan Prize(the Japanese equivalent of the Nobel Prize) in 1995 and was asked to say a few words, he simply pointed to the celing lights and said "all this is going". I think we'll see this happen within 20 years or so.
- "Hear that?! The percolations are imminent! Cease your ingress!"
One of my favorite toys they have is the radio set wall clock . It checks itself every hour, and is great for things like daylight savings time, etc.
I am sure that this is not the only place to get this stuff, but a second source is always nice.
Check out the Vinny the Vampire comic strip
"It is a greater offense to steal men's labor, than their clothes"
Having purchased a ton of flashlights myself, here are some things you should realize before making a LED light purchse. Most flashlight review sites fail to point out the disadvantages of LED lights:
- Cannot focus the beam, as the reflector is inside the LED itself
- Thus... the beam must be either non-focused, or too focused. Short focus LED lights have a very small range of 30 feet or so, while exceptions (like the PAL light) have such a focused beam that it is useless in close range)
- The "white" light, while impressive and cool, is not that great for night-time viewing. It can ruin your night vision, and does not display contrast as well as the yellow light. (of course, no one wants to put a yellow LED in their flashlight, even if they exist, because it's not "cool")
- pricey. (new technology is always pricey)
So.. my advice is to find a local outdoors retailer that has these lights, or better yet -- look for a flashlight freak like me that has these lights, borrow them, and try them out before you plonk down $20+. Personally, I find that the headlamp Tekka (from Petzl) works wonderfully for proximity lighting, and combined with a conventional Xenon lamp like the Bison, you have your long range covered as well.Just my 2 cents.
They must have also done some silly stuff with the LED selection, wiring and/or batteries, because you can get reds much brighter and cheaper than any blue, and in many different wavelengths.
+5:offtopic,but anti-American
I'm referring to the big, heavy kind. Just so that I can club "Daniel Rutter" in the head, for having that damned popup ad on his site.
-k.