LED flashlights: worth a darn?

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!

You no longer need a flashlight to double as a nightstick if you have a G2 (or equivalent). All you need to do is shine the G2 in their eyes which WILL temporarily hurt their vision, and then kick them in the balls...

I'm not a flashlight aficionado, but the G2 is my favorite non-led flashlight by a long shot. Very bright, small and light form factor yet still big enough to get a grip on, textured surface area for gripping, and a price point that is ok.

Wayne

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.

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

Try some Penetrox on the Maglite threads. It works very well on my old Kel-Light(copied by Maglite)

Randy

I remember years ago like 1975 or so when a cop and his partner stopped into the gas station I as hangin out at. The cop wanted some batteries for his 6 cell and was going for carbon-zinc on price and his partner jumped in and told him to get the alkalines.

Why asks the rookie? Cause they are heavier said the old timer.

Wes

Yes, the Streamlight "Tasklight" uses 3 AA's.

Note, however, that this and most 3 cell Luxeon lights do not have electronic regulation so brightness will droop some as batteries age

-- and will go clear out when the batteries are only about half exhausted at about 1.2 volts per cell. (Fully exhausted is about 0.8 volts per cell). I'll note that folks also often dump half-dead batteries out of Maglights because they start getting pretty dim at

1.2 volts per cell.

A better choice might be a 2-AA light which *must* employ elex to boost the voltage --and regulate current while it's at it. These will suck the batteries clear down to dead. So you only have 2/3 the available energy with 2 cells, but you use all of it so battery life is probably about the same with less bulk. The difference in cost would buy a lot of batteries, but having fairly constant output is nice.

Aside from that, the Tasklight is a pretty good flashlight if you don't mind the length. It has a very good reflector in it that obviously was purpose-designed to use with a Luxeon. I think WW Grainger carries these. They might even be at Sears now.

You can also get a conversion kit (Terra-Lux, about $30) to convert a Minimag 2AA to 1-watt Luxeon. These work well, make a nice compact light with fairly constant output over battery life (some droop but not bad) and they do a pretty good job of sucking the batteries nearly dry. The beam isn't as uniform as that from the Tasklight, because the reflector isn't nearly as good, but it might make a light that is more satisfactory overall -- and cheaper to boot.

Great, when taped to a chunk of pipe!

Right. $300 for a 5-watt Luxeon is insane. If you need that much light, krypton or xenon incandescant is still the way to go.

The 5-watt Luxeon itself is only about $20, but they're tricky to heatsink and they run hot. Takes a big package to dissipate the heat.

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

To start the campfire, maybe, or the barbecue?

Dan

You call the cops at 2:00 am to bring two things: armed response, and lots of light. I still keep a phone by bedside, but think of dialing 911 as part of the aftermath, not the first response. In theory, anyway. I'm in no hurry to test it.

Anyway, there's something primally satisfying about a strong portable light. Costco was selling big "flashlights" earlier this year; 10" or so diameter reflector, I don't know how many millions of cp. My son bought one for me for my birthday. One of the best presents I ever got. :)

Get the Maglite. They are cheap, at least here in SF. They sell them at Costco for very little.

Besides if you get a long one, like with 6 "D" batteries, you can use it as a club, in case you need to defend yourself in an emergency. They have a fair amount of weight behind them , so getting hit over the head with one would not be a great deal of fun.

Even the small ones with 2 AA batteries aren't all that bad.

Abrasha

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

Recent uses:

1: Checking for down power lines during "the storm" 2: Light while neighbor Con cut up a downed tree that was blocking the street, which would have impeded progress of emergency vehicles if they were needed that night. 3: Checking the seas at the end of my dock to see if my boat was about to get swamped during the other storm. There wouldn't have been anything I could have done about it, but I slept much better knowing it was OK.

Other use: checking noises in the night when it's dark as the Earl of Hell's waistcoat AKA looter repellent in metro during a power outage or checking for bear vs raccoon in the woods. Bears really don't like bright lights, raccoons don't much give a damn but they're not worth worrying about.

I carry a smaller one in the boat in case I have trouble and end up limping back to camp in the dark. I can find camp with GPS, but I don't have every rock on Lake Vermillion waypointed in the GPS. There are rocks all over that 40,000 acre lake.

I prefer the "C" size myself, I have short fingers and can grip the smaller diameter better.

Dam thats an oldy..Ive got a Stud-Light..which I think is an early Kel-light

Gunner

"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

Google "Kubaton Techniques"

Gunner

"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

In an emergency situation...when the stores are cleaned out of most items...C batteries seem to be the very last items left on the shelf as so few people use them anymore, and then generally only in older radios and miniture TVs.

So Ive made adapter shrouds to hold C batteries in D sized devices.

Gunner

"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