AA LED station light

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AA LED station light

Postby pebblepoint » Mar 23, 2006 10:57 pm

The best "on station" sighting light I've ever used was a green LED potted to the top of a 2 AA battery holder. I bought several about 10 years ago from B&C. However, Cecile said it was a one time thing, done by a friend of hers.
Since then, I've trashed all but 2 or 3 and am looking for more.
Tonight, I potted a green one onto the battery holder and watched it for several hours. No problems. But I think I'm suppossed to put a resistor in.
Obviously, I know very little about LED's. Any tips?
Thanks.
don
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Postby Scott Shaw » Mar 25, 2006 3:37 pm

I think most LEDs require something like 3 volts (or no more than three, check the LED specs). I've rigged a couple with AAAs. Just get a 2-AAA holder and solder the LED leads onto it. I think the long lead on the LED is (+) positive. They are working fine years after.
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Postby Realms » Mar 25, 2006 9:49 pm

Your right about needing a resistor. Place a 1k resistor in there and run it between 1-2.5 volts (different color leds require different voltages). Current draw on those types of leds are typically only about 30ma. This would explain why I burned so many up using 2300maH batts and no resistor. Also the anode leg is the longer of the 2 and is positive. If you have em cut even already, look inside the led. The annode will be the smaller electrode.
Good Luck!

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Led target light

Postby pebblepoint » Mar 26, 2006 9:28 am

Never mind.
Friday,I bought several AA 2 cell holders, several green, yellow and red leds (2.1 volts to 2.6 and experimented.
The short leg goes to the negative. With the kind of holder I bought, I merely pushed the legs into the battery holder holes, bent them upward and liberally applied silicon seal to the top, thereby sealing the contacts and glueing the led to the holder.
Our favorite was the "super brite" red one for about $2.50.
All survived a 5 hour survey trip yesterday and were used on every shot by 3 people. Try it. You may like it.

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Postby potholer » Mar 29, 2006 11:29 am

I made some on the suggestion of a friend last year, who'd been impressed by seeing them in use when he was over in Mexico some years ago.
I used cheap superbright red LEDs (~30 cents each from my UK component supplier) with 470R or 150R resistors, soldering the LED and resistor to a battery-holder clip, then potting round the resistor and LED base with epoxy.

The brightness difference between the two wasn't hugely noticable close up. In relative darkness, both seemed very brigh if looked at head-on, though the brighter one does seem to have a slightly larger apparent size if viewed from some distance.
Running off a pair of fresh AA alkalines, with one or other resistor, they pull 2.5 and 8mA respectively, which would give expected runtimes of ~1000hours or ~350hours, though in practice they will start to slowly dim from the word go, and and actually still be shining more dimly for somewhat longer than those figures suggest, as is the way with LEDs.
Off reasonably charged NiMH cells, the current+brightness are about 2/3 of the initial alkaline figure, with runtimes likely to be proportionately longer, but with maybe a little slower dimming than with alkalines.

I took a few out on an expedition last summer, and though they never got used for surveying, they proved excellent as path-markers for night-time navigation across a limestone plateau, being clearly visible from several hundred metres away, and even in mild mist, could still be seen from a reasonable distance.
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Postby lbartel » Mar 29, 2006 12:30 pm

I've built several of the AA types. I always soldered the LED on the end of 2 or 3 feet of wire. This lets me stash the battery pack in a crack or somewhere and tack the LED to the station with a bit of mud. I've also used one with a 3V coin battery about the size of a quarter. Slip the battery between the legs of the LED. If it doesn't light, reverse it. Secure it with duct tape. Can't get much simpler than that.

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