Harbor Freight 4 LED $7.00

There is much more to it than that- parallel LEDs are more reliable than any other configuration and putting the full battery voltage across the LEDs maximizes sensitivity of current to battery voltage so that when the user notices less than satisfactory light output he/she still has ample use remaining to change out the batteries- sort of like the low gas level warning on the car dashboard.

The Electronic Goldmine sells a 4 white LED flashlight for $1.99. Item # G15184 Watch for the line wrap:

Based on the catalog pictures, it looks like the Harbor Freight light has a metal body, while the Goldmine's is plastic. But I'll bet they use the same LED's. I have the Goldmine unit - there is a bluish tint to the light it produces. Does yours produce a bluish tint?

As Watson mentioned, overdriving LEDs does reduce their life and their light output, so your thinking seems right on target. But for either a $7.00 or a $1.99 4 LED flashlight, it's probably not worth the effort to incorporate a dropping resistor - unless experimentation, rather than function, is the goal.

Ed

"Henry Kolesnik" wrote in news:8ovje.1965$ snipped-for-privacy@newssvr11.news.prodigy.com:

Are there now other white LEDs that have a higher current rating?

The Harbor Freight number is 3653 and if there's any blue tint to the light I can't see it. tnx

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I removed the lense cap, it's an force friction fit. I looked thru the tube at a bright lite and I saw what looks like there is something in series with the pcb arc and the case. I'm guessing it's a surface mount resistor, and guess it's about 1/8 watt size. It should be possible to measure it but that requires a long slender probe which I'd have make. If I make one I'll report.

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Yes, that would be good way to market it. ;-) It does make the design sensitive to battery type. I have one that does not work properly with CR123A Lithium batteries that otherwise fit (it's a 5W Luxeon module with no series resistor that puts out less than a 3W type unless you use special batteries).

Best regards, Spehro Pefhany

I just made a probe out of solid No. 12 house wire and measured the resistor at 8 ohms on my Fluke 87. So I^2*R=0.127*0.127*8=0.129 watts. I guessed the reisitor looked like 1/8 but I was using my recollection of what 1/8 watt radial lead resistors look like for size. I should have done all this with my original post and not wasted all those resources. But hind site is 20

Jeweller's saw? Sort of like a hacksaw with a thin narrow blade (shorter than a hacksaw but with similar throat). As with files, skilled folks can do wonderful things with them.

Best regards, Spehro Pefhany

ROFLOL, that's a good one!

:Jeweller's saw? Sort of like a hacksaw with a thin narrow blade :(shorter than a hacksaw but with similar throat). : Spehro Pefhany

Wow. Just look at the throats on some of these dudes:

When I heard it, I thought of something like this (photographed with an actual fretboard, no less):

Radio shack use to sell a self flashing LED.

I've seen the strobing on rapidly opdating LED displays when either they moved rapidly. I would think the flash rate would be at a level that it wouldn't be noticed under most normal conditions. I'm sure there must be an optimum flash rate for this type of use.

"mc" wrote in news: snipped-for-privacy@mustang.speedfactory.net:

Actually,the Nichia white LEDs have a drop of about 3.5 volts at their rated current;25ma. The spec sheet,IIRC,said 3.2v-3.9v. the 10 I checked were mostly 3.4V.

"Watson A.Name - "Watt Sun, the Dark Remover"" schreef in bericht news: snipped-for-privacy@corp.supernews.com...

Well,

My dictionary considers it a synonym for milling cutter. I use a small handy tool for PCB modifications and (very) smal PCBs that I don't want to etch. Guess we have very different dictionaries :)

petrus bitbyter

"Frank Bemelman" schreef in bericht news:428f57cc$0$64077$ snipped-for-privacy@dreader14.news.xs4all.nl...

Correct, but... I checked out the two dictionaries I own and both know the word "fraise" as a synonym for "milling cutter". Only one of them also mentioned it as a part of a fortification. So I was really astonished to hear that the word was virtually unknown.

petrus bitbyter

of

sufficient.

White LEDs that have that much voltage across them have too much current going thru them. I suggest you read the specs for a common white LED here.

Confusingly, at least on European website called something that looked like that (presumably with finer teeth for metalcutting) a jeweler's saw. Nothing to fret about, I guess.

Best regards, Spehro Pefhany

There IS a

circuit.

than

the

You forgot to add: "that when the user notices less than satisfactory light output he/she still has ample use remaining to change out the LEDs"!!!

Running the LEDs at excessive current not only makes them a lot brighter, it makes them last much shorter, and guarantees the flashlight maker another sale in a few years, if that long!!! :-P

beleive

all 4 are

LEDs are

I'm

substantially,

can see

zero on

Man, for those prices, you can throw them away every time you change the AA cells! But what I find problematic is that the length of that three cell monster is over 7".

Yes, and multicolor LEDs are available these days that do patterns and such like. But nothing at the component level with white LEDs that I've seen. There are high power white LED modules available that run off of (say) 12V but they are not from LED manufacturers that I've seen, and they are probably too expensive for use in a >Also, if pulsing were going on, you'd see stroboscopic effects when you

Zero, more than likely.

Best regards, Spehro Pefhany