LED flashlights: worth a darn?

On Thu, 6 Oct 2005 20:34:50 -0500, "RAM^3"


Better to mount a NOD..second generation ..perhaps something from Litton or even something 1st Gen from Russia, which is good for around 200 meters. If your critter can shoot back..having that spotlight as an aiming point is not a good thing.

"Pax Americana is a philosophy. Hardly an empire. Making sure other people play nice and dont kill each other (and us) off in job lots is hardly empire building, particularly when you give them self determination under "play nice" rules.
Think of it as having your older brother knock the shit out of you for torturing the cat." Gunner
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    That depends. The word which came back from 'Nam about the high intensity Xenon searchlight was that it was so bright that nobody could manage to aim anywhere near it at night -- it dazzled the eyes of the opponents too much, so none of the shots aimed at it came anywhere near.
    But -- for something not too bright, and not aimed directly at the eyes -- I can see your point.
    Enjoy,         DoN.
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On 8 Oct 2005 03:32:57 GMT, snipped-for-privacy@d-and-d.com (DoN. Nichols) wrote:

I never worried about the bullet with my name on it. It was those addressed to "Whom it may concern" that were bothersome. Particularly those emitted from crew servered or fully automatic small arms.
Gunner
Confronting Liberals with the facts of reality is very much akin to clubbing baby seals. It gets boring after a while, but because Liberals are so stupid it is easy work." Steven M. Barry
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I did say 'better,' not 'brighter.'
Better, in that it's as bright as the 2D cell maglight, but smaller, more reliable, and longer battery run life.
It's small enough that I can carry it in a jacket or riding suit pocket all the time - which would be impossibly awkward with even a 2D maglight.
One of the problems I find with the maglights is, the anodization tends to prevent the tail cap from making good electrical contact with the body tube. The lights often won't work unless you twist its tail.
Even though the maglight is environmetally sealed with O-rings the contact point between the rear cap and the body is *outside* of the O-ring, and as such is susceptible to oxidation and corrosion over time.
Jim
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Has anyone used a luxion 1 watt in a 2AA maglight using NiMH batts? How well does it work?
Wes
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On Wed, 05 Oct 2005 00:24:17 -0400, snipped-for-privacy@lycos.com wrote:

I haven't, but it would work just fine. A 2AA Luxeon light needs voltage boost elex because the Luxeon runs at about 3.6 volts, so some degree of regulation is implicit. Fully-charged NiMH cells are lower in voltage than fresh alkies, but the discharge curve is flatter.
The TerraLux module would work just fine with NiMH cells.
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With the 3 and 5 watt LEDs available, the amount of light generated is incredible when compared to the old technology. The 5 watt Surefire is around $300 but a 3 watt can be had for $70 with single LED and fixed focusing lens. MUCH whiter light with less heat and more compact in size than the incandescent/halogen/xenon types. Respectfully, Ron Moore

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On 4 Oct 2005 17:41:30 -0700, Dan_Thomas snipped-for-privacy@yahoo.com wrote:

Even the 1-watt Luxeon LED's produce brigher light than the krypton bulbs used in 2D Maglights and 2AA Minimags. The 3-watt and 5-watt Luxeons are brighter yet.

A Luxeon works great in the reflector from a 2D Maglight. I made a 3-watt light using a 2D Maglight reflector that compares favorably with a 6-volt Everready lantern, lights up treetops 100 yards distant.
There are also plastic collimators that produce about a 12 degree beamwidth from a single Luxeon. They're about 3/4" dia, considerably brighter than a Minimag.
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Christopher Tidy wrote:

I live in a marine enviorment and internal corrosion did them in. Even the 'free' one - left in the snow beside my truck after being obviously used while stealing my battery. that one was a big three cell COP flashlight. Best possible use is as a club.
Regards. Ken.
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    [ ... ]

    [ ... ]

    [ ... ]

    Perhaps you should do what I do with each new flashlight with a machined case -- LED or MagLite -- lube the threads and the O-rings with Vaseline. And if exposed to direct salt water, unscrew it and wash off the freshly exposed surfaces with tap water prior to re-lubing it and re-assembling.
    All of the LED flashlights which I have are as likely to fall victim to salt wate as the Maglites are -- similar construction, similar materials.

    :-)
    Enjoy,         DoN.
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Far better than any kind of conventional grease is Penetrox by Burndy. Available at industrial electrical supply houses, it contains zinc particles which puncture the alum. oxide on the joint faces providing a conductive path that is sealed by the grease carrier. One application will last for years, and you don't have to occasionally turn the threaded joints to reestablish contact.
Randy
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On Tue, 4 Oct 2005 23:52:06 +0000 (UTC), Christopher Tidy

The Maglight was a very significant innovation circa 1979: a rugged and reliable flashlight at a relatively high price : > $20 then, >$50 in today's $ with inflation factor of 2.68 between then and now. It was the first "really good" flashlight.
One problem with the Maglight is that it uses a threaded aluminum tailcap as part of the current path. Incidentally, Maglight is not so named because it's made of magnesium (it isn't), but after it's designer Anthony Maglica.
The threads can't be anodized because an anodize film is non-conductive. Non-anodized aluminum threads still oxidize and sometimes gall though a bit of lube helps a lot. Neither oxidation nor lube helps conduction of low voltage a bit.
Another problem is that it (as any incandescant flashlight) loses nearly 75% of its brightness over nominal battery life to 0.8 volts per cell. Most users change batteries long before the cells are fully depeted for that reason.
The "spot" is not uniform. It's mottled with artifacts of imaging a glowing filament. This is not good for inspection or for hunting for small objects.
If the light is dropped when turned on, the bulb will usually fail. If not, the bulb will usually fail when first turned on -- which is exactly when you need a light or you wouldn't have turned it on.
Now, 26 years later, the Maglite, with its wonderful (and deserved) reputation, is obsolete. It definitely deserves a place in history.
Luxeon LED's are brighter than the krypton bulbs used in most Maglites, have life of 50,000 hours, and won't fail when dropped. They produce a very even white beam. The light does not change color at reduced power -- and electronic regulation can maintain constant brightness while fully depleting the batteries. Luxeon lights are available in machined aluminum bodies with O-ring seals that are made as well as a Maglite, though most are considerably smaller and lighter. Some use internal battery carriers that do not depend on aluminum threads as a return conduction path. One, Zweibrueder, even uses gold-plated contacts. Good 1-watt Luxeon flashlights, with electronic regulation, are available in the $40 to $60 pricerange -- which is comparable to the cost of the Maglite (in todays' dollars) at the time of its introduction in 1979. (Inflation factor from 1979 to now is about 2.68.)
Flashlights using several individual 5mm LEDs are useful too, but different. In those, each LED produces its own beam with it's own integral lens. This cannot be improved with a reflector or array of reflectors. They also run at much lower power than a Luxeon and use that power less efficiently. But they're still quite sufficient for walking thru a dark house without tripping on anthing or anyone.
The Luxeon is more of an omnidirectional radiator, more like a lightbulb. As such, it needs a collimator or parabolic reflector to form a beam -- and, given such a collimator or reflector it can produce a tight, intense, uniform beam.
I might mention that I'm in no way affiliated with Luxeon -- or any other business for that matter. I'm retired. I just like good flashlights. I have four commercial Luxeon flashlights, some better than others, and I enjoy making my own as well. 1-watt Luxeons are only about 6 bux each, 3-watt jobs are a coupla bux more.
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snip--
The light does not change color

Don,
Is it possible for you to explain in such a way a machinist (that lacks electronics smarts) could understand how the voltage is established and regulated? Seems the voltage drop as the batteries depleted would present a problem.
TIA
Harold
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wrote:

Better flashlights incorporate a switching type regulator. These can be over 90% efficient in converting one voltage to another. Actually in case of LED it would be converting a battery voltage to constant current so that as the battery voltage drops the switching regulator would take more power from the battery to maintain the constant current that the LED requires.
--

Boris Mohar



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On Wed, 5 Oct 2005 02:06:38 -0700, "Harold and Susan Vordos"

I'll try. First, It's LED current, not voltage, that is regulated. LED's want to operate at a given current; the applied voltage necessary to get that current can vary some from LED to LED and in a given LED with temperature.
OK, but how?
They first need "enough" voltage, which for white LED's is somewhere around 3.5 volts plus or minus. In lights that use a nominal 3-volt supply (as two alkaline cells), the voltage must be electronically boosted. This is usually done with inductive "kick" in a very small coil operating at high frequency, above 100 KHz.
The LED current is sensed in a small resistor, which produces a voltage proportional to current. For example, a 1 ohm series resistor would exhibit 0.350 volts for a current of 350 mA as in a 1-watt Luxeon. This voltage is compared to an electronic voltage reference. The difference between sense voltage and reference voltage comprises an "error" signal. This signal is amplified and used to drive the electronics -- a positive error decreases output, a negative error increases it. Because it is amplified, a small "error" results in a large change in output current -- or, conversely, small error voltages can vary the output over a large range.
Because the elex can "boost" voltage, the result can be essentially constant current to the LED with battery voltage varying from 3 volts (2 new cells) down to 1.6 volts (2 nearly exhausted cells).
The elex necessary to accomplish this regulation are quite inexpensive (coupla bux in volume, maybe less) and fit on a circuitboard about the size of a dime though a bit thicker. Maybe a stack of 3 dimes.
A mechanical analogy might be the flyball governor on a steam engine. As speed increases, a valve is closed reducing steam available to the engine. When the engine slows under load, the balls droop a little, opening the valve to feed more steam. It would also work if load was constant but available steam pressure varied. If steam pressure droops, the speed would decrease just enough to open the valve enough to keep pulling the load at near set speed.
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snip---
I think the part that had me the most confused is not understanding that DC was converted to AC so it could be transformed to a higher voltage. That part had me totally stumped. Armed with that little bit of info, the rest makes sense, although it's certainly beyond my capability.
Thanks for sharing your expertise!
Harold
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On Wed, 5 Oct 2005 21:41:01 -0700, "Harold and Susan Vordos"

They're usually "flyback" converters. Low voltage is applied to an inductor, building up some current. Then the source is abrubtly disconnected by a transistor. Inductive "kick" produces a higher voltage that is routed thru a diode (electronic checkvalve) to the load.
A rough mechanical analog might be a hammer. Mathematically, velocity is analogous to current and force or pressure is analagous to voltage. F= MA, A is acceleration or rate of change of velocity, E = L di/dt E is voltage, L is inductance, di/dt is rate of change of current.
Some force accelerates the hammer to some velocity over a period of time. Then the hammer strikes an object which tries to rapidly reduce velocity. Result is much higher force being exerted on the object than was ever applied to the hammer.
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Don Foreman wrote:

<snip>
The Maglite might be obsolete if you're a flashlight enthusiast who wants the very latest technology, the absolute brightest beam, the best battery life, and so on, but from the point of view of the man on the street who wants a good flashlight it's alive and well. We're comparing very good flashlights here and the differences are pretty small when it comes to everyday use. A 2-D Maglite and your Luxeon flashlight are both going to be better than perhaps 95% of flashlights in high street stores. The Maglite sells because it's an uncomplicated, tried and tested design from a well-known company, it's durable and it's damn bright compared with the other 95%. What's more, it's widely available.
Chris
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On Wed, 5 Oct 2005 11:34:17 +0000 (UTC), Christopher Tidy

Very true. Obsolete does not mean useless by any means.
I readily admit to being a "flashlight enthusiast". Have been all my life!
On obsolete stuff: last week I found a 10 x 50 Carl Zeiss binocular for $7 at an "antique" store up north. It may be of WWII vintage. Eyepieces are individually focussed -- there is no common focus barrel. Result: the axes are perfectly aligned after all these years. The optics are incredibly sharp: I've never looked thru binocs this good. There is a reticle in one side, don't know what it is but I'll figure it out. Probably for estimating range to a tank of known size or something.
Another surprise: for some reason I can hand-hold these 10X glasses. I don't know if it's the weight or balance or what, but I have trouble hand-holding most 8X binocs. Not so with these!
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I use my converted 2AA Mag *everyday* and I wouldn't go back, even though the company pays for bulbs (reg) and batteries.
As far as the original question: yes, worth a darn.
Regards,
Robin
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