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I have many of Cheap and Outdated LEDs (In thousands) lying around.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. These will usually fail sooner or later so I feel like avoiding series configs and aim for parallel.

 

Build a multiplexed LED matrix.

If the phosphors are bad it's no point to use them for lightening panels.

 

Keep other ideas Rainin'!
Thanks for the input.

 

Use the "bright" ones for automatic lights in dark areas. You open up a closet/cabinet door and a light comes on.
Build a little "flashing" LED gizmo that you an plug into a wall socket, see it from far away, and know if you have power to that socket.
With a decade counter - make flashing lights to amuse your friends.
Put flashing lights near your fish tank to amuse your fish.
If you ride your bike at night, build a flashing light gizmo that you can put on your seat.
Add flashing lights to any gizmo that you can see from a distance to see if it's "on"
Add flashing lights to your cat's "litter box" to confuse and anger them.
Add flashing lights to your dog's bowl so he/she can find it easier.
LED night lights
Make a Jedi sword of LEDs and give it to a youngster.
Add LEDs to your magnifying lenses for better lighting
and on and on...

 

really neat ideas dude. will help.
thanks.

 

Make LED tester from a constant current source, and LDR and moving needle meter that shows brightness.

Then quickly sort them into groups of the same brighness and bag them.

After that they are useful again, to make any low usage lighting devices like garden lights, power blackout lights, etc etc.

You could even use them for constant use lighting but just de-rate them a lot in current so you get long enough life. Of course you have to use more LEDs but they are essentially free.

 

You could make small or large 7-segment displays and change the color by putting transparent colored acrylic in front of them. You could use these for scoreboards, clocks, timers, etc.

You could of course also make the ever-popular Larson scanner (Knight Rider) display.

 

Thanks for all the replies,
You'll see these in coming instructables Shortly,
Thanks.