Cheap LED, Batteries and magnets

Hi, I want to make a whole bunch of lowtec-throwies, just a simple version to decorate and take pictures here, not the ultra-bright highly magnetic kind.

The problem right now is that 200-300 throwies with cheap LEDs would cost more then $100 if I get the parts at our local electronic store (and that without magnets).

"besthongkong" has 1000 LEDs for $10+$10S/H (=2 cents each) but does anyone know another cheap source with a larger variety and colors of low cost LEDs, maybee even low current ones? Maybee even in Europe?

Second thing: Batteries. Lithium cells are rather pricey at that quantity, and cheap button cells seem to do the job.
I had a couple of 1,6v LEDs on two button cells with diods I had lying arround (voltage drop). It was not very bright but they still glowed a week later.
I had a cheap 12 pack assorted buttoncell blister, and I found
http://www.dealextreme.com/details.dx/sku.61
But they seem to have even worse quality ;-) Idd probably have to use three or more and still throw some out.
I remember an experiment using wire and coins, lemon juice or vinigar, which made a LED glow dimly. Any Idea how long before this DIY-Batery runs out?

Third thing: Magnets!
DX has 20 for less then $2. but I guess at that weight I could just magnatize some scrap metal and cut it into pieces.

Thats about a third of the costs even with all the shipping :-)
Anyone here that knows any other good site for LEDs, magnets and such that ship to europe?

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xproplayer9 years ago
wow i just did the math and i can make 1000 throwies for only $134!!!!
schorhr (author) 9 years ago
Thanks for the shop links! Electronic Goldmine will not deliver to europe. Twin city suply has no info on shipping cost prior to ordering, and cheapBatteries has a minimum order of $500 for international orders :-(
heapBatteries has a minimum order of $500 for international orders :-(

Oh, don't you just HATE that ? grrr
schorhr (author)  Goodhart9 years ago
As I posted a bit below I have found almost-free batteries ;)
In the long run, they would probably end up being more expensive (efficiancy wise, if you buy all the materials yourself) :-)
schorhr (author)  Goodhart9 years ago
Do you think so? Lemonjuice, vinegar or saltwater for the cell, clay and straws seem rather cheap (though I still need to figure out what size of acidcontainer will do the trick). Plus its fun to build. Since I can get a pack of straws at the dollar store, and several meters wire and hundreds of galvanized nails, I think it beats even the Dealextreme buttoncells
Well, keep track of all spent, and given how long they last, maybe you can offer some statistics that will prove it one way or another :-)
schorhr (author)  Goodhart9 years ago
Yep, I will do that. Each way, it would be a nice solution; Especially if I ever take throwies outside of house&garden, having more or less enviroment friendly batteries would be a plus. Last time I placed about 15 throwies in town, after a week I could only retrieve 12 or so. Having lithiumbatteries rott somewhere is probably not good ;-) Well, it even works with water (weakly) and saltwater, though after I disolved quite a bit of salt into the water the chemical process really boosted. After just a few minutes the nail turned nearly black (see image)
lembat8.jpg
schorhr (author) 9 years ago
I think I solved the battery issue :-) Well, at least I played arround with lemons a bit, I allways wanted to do this; Everyone knows the potato or lemon battery, but I have never build one, so I got a few lemons today, hehe. If life gives you lemons- make batteries. I tried cloging up pieces of plastic straws with clay, fill them with pure lemonjuice (and some with concentrated vinegar essence) and plug galvanized nails in one end, copper wire in the other- but no luck lighting a LED with it. Unfortunaly I lost my ampmeter. I am unsure why it is not working, maybee more metal area is needed to provide enough current for the LED. The voltage (I read 1v per cell somewhere) seems just fine as 3 lemons will light the red LED wich has a forward voltage of 1,6v if I remember correctly. Still, it glows rather dimly, even if I connect 12 lemon slices together (but I think resistance of the weak connections I made plays a roll too), so I might try getting some copper and galvanized plates instead of nails and wire to increase the acid-exposed area. One thing is for sure, the straw-battery-chain would make a nice bracelet :-) Too bad I did not make a picture of the second batch I made which look nicer (but did not work either). I wonder how long the LED will glow. I guess untill the metal galvanized and/or the acid is neutralized from reacting? One word of advice: Do not fill containers with lemonjuice using a syringe, at least not poke yourself with lemonjuice, it hurts badly.
lembat1.jpglembat2.jpglembat3.jpglembat4.jpglembat5b.jpglembat6.jpglembat7.jpg
Doctor What9 years ago
CheapBatteries

If you are looking for batteries, look no further. When you buy in bulk they cut the prices. For instance, Lithium Ion Button cells 3v go for 25 cents a battery if you buy more than 100.
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