Ideas wanted for "Consuming" Outdated LEDs

Hello all!
I have many of Cheap and Outdated LEDs (In thousands) lying around. These were purchased long time ago (2003~2005) when luxeon Stars were hardly available and costed Rs 1000 a piece. These LEDs are-
5mm 20 deg White ~100pc
4.8mm "Straw Hat" Low dome 100 deg White.~ Many

1)Both of them are rated at 20ma, 3.2 volts.
2) Straw hats are twice as better (Life, brightness, Even-ness) than low beam angle 5mm ones
3)I learnt the hard way using these in many precious projects. Now I know very well that 5mm LEDs dim considerably even at 20ma after a year intermittent use. I had made 36-LED matrixes (about 2 watts) with good spacing between LEDs, Legs uncut still went dim after a year.
4)There is a huge variation in Tint, Voltage and output of these. Straw hats are better , but still
5)These are not entirely Cheap in money per-se. Costed 3 Rs per piece. Today a reasonable spec Chinese 350ma Star costs 40 a piece. If we consider a bunch of 18 of these to make that wattage, They add up to Rs 55
6)Advices to throw them in the bin/ Donating/ smashing with bulldozers./ Overvoltage Fun etc are not my idea.
7)Don't want to spend tremendous time/energy/money than they're worth.

Is it worth your time to use them? You could:

Make emergency lanterns or decorations. Wire dozens in arrays that drive them at 10 mA, expecting 4.5-5v input. Connect these to USB-5v chargers or 3x(alkaline) cells as needed.

Make highlights for a room. Create a long string going around the upper trim of a room. Always-on at low current.

Thanks for dropping in, AnAppleSnail

I was thinking of these ideas, Wire many of them (overkill) and keep them to 10mA. I could then use them as Night time security lights, where tint and even brightness won't matter much.

Any ideas of power suply?

Keep other ideas Rainin'!

Yeah, I came to the same conclusions. Check out Pak-lites for inspiration. As for decorations, good ol' Christmas lights or rope lights powered by mains..

StarHalo said:

Yeah, I came to the same conclusions. Check out Pak-lites for inspiration. As for decorations, good ol' Christmas lights or rope lights powered by mains..

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Pak lites! These are dime a dozen here locally; Actually Rs 30 a piece minus all the quality.

For string lights,
240v X RMS Divided by LED vf? Crude and dirty but may work!

Home decoration was my initial thought, too. One could give some emphasis to bookshelf items, etc. The construction could be very simple, just solder the leds directly to a dual core wire (parallel) and attach a driver and power supply to the other end.

You could also put them in your clothes. For safety, utility, or party usage. A cap light, for example. A small low current driver could be hidden in a little fabric pocket and the battery could be attached with little magnets when light is needed.

Joule thief circuits could also be used to make some small emergency lights that could be put everywhere.

Put a bunch in the microwave and start it, be sure to film the results. :devil:

BHVM, here's what you do!

First, go watch this... The 500-LED "Dominator" http://www.youtube.com/watch?v=NkkU0UO3sek

Since you have thousands of LEDs, make two Dominators (and send one to me)

argleargle said:

First, go watch this... The 500-LED "Dominator" http://www.youtube.com/watch?v=NkkU0UO3sek

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Ugh, that's worse than the microwave idea..

StarHalo said:

Ugh, that's worse than the microwave idea..

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The microwave idea is an AWESOME idea, it's fun to put things in and see what they do, lol.

Luxeon colored LEDs are not bad for what they are even in this day and age, especially the red and cyan flavors. CREE XR-Es retrofit nicely into LED nightlights. Most if not all LED nightlights employ 5mm LEDs powered by a capacitor fed full wave bridge. The high forward voltage of XR-Es makes them very tolerant in CV applications. The Feit Electric ones I have all over the house puts out about 3.5V at 15mA [tested using an XP-G]. In addition, a 20mm or even a 10mm star in itself is sufficient heatsink for the LED at that current level. When I am at friends houses and see their nightlights with near dead 5mms, I would offer to do lamp swaps on them with "obsolete" CREE XR-Es and XR-Cs, often with spectacular results: [3-4 times the output]. With this method I consumed about a dozen XR-Es before I moved on to XP-Es.

As for 5mm LEDs, I haven't found a use for them. Even at 15mA they have a tendency to degrade in intensity under continuous use within a year. I'd say buy cr2016s in bulk, buy stamp ziplocs in bulk, buy magnets in bulk, then make LED throwies. Pak-lites don't use complicated circuitry, just a simple 9V snap connector and a couple resistors, yet they are very popular.

7)Don't want to spend tremendous time/energy/money than they're worth.

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:lolsign:
As a hobbyist, I'd say that statement is invalid. To attain the objective of having fun and being productive while doing it, more often than not the act of salvaging a component from a junked appliance and root it in a circuit drawn from scratch alone is spending more time and energy than the components worth. What I could make can be bought from stores, but wheres the fun in that?

Illum said:

make LED throwies

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Was going to suggest this also, but no one's ever found a productive use for throwies either, so the Pak-/survival-light idea still tops the list (and CPFers like buying survival lights, throwies not so much..)

StarHalo said:

Ugh, that's worse than the microwave idea..

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bose301s said:

The microwave idea is an AWESOME idea, it's fun to put things in and see what they do, lol.

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I used to hook unwanted 5mm leds to wall current. With all these new wicked emitters, you might want to wear sunglasses, face protection and do that outside. When you hook a 5mm direct drive to a 12 volt car battery, you might get a neat sparkler effect for up to 3 seconds. Wall current is more like a flashbulb.

I wonder what the cool failure mode of the current crop would be? It's easy to blow one up, but not so easy to find the COOLEST way to blow one up!

...and Ilum, your posts are awesome as always! 110%, what that guy said!

Anything I can think of I can probably do with far far less effort using strip lights which are dirt cheap these days.

I would just give them to a local high school electronics shop. Performance does not matter when you are learning.

Semiman

+1 to what Semiman said. You might even get a charitable donation receipt for your taxes.

...star field ceiling..

StarHalo said:

...star field ceiling..

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My vote's on this

StarHalo said:

...star field ceiling..

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+2 on this, combined with several packs of those "glow in the dark" ceiling star stickers.

How about making a looong string of lights powered by a longlasting battery and hook this up to a helium-balloon. Send it up in the air on a dark night.
Who knows? It might result in a number of UFO sightings