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single wire LEDs - why don't they exist?

Because such a thing would totally solve my LED jewelry problems. I'd love to able to just solder an LED onto a necklace chain without needing to slice the chain. So why can't I? Curious.

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seandogue7 years ago
Hi, I read thru most of this thread and I think you're not seeing how an led does it's thing.

An led is like a one way valve. electrical current doesn't just go in and change into light, like gas might go into an automobile...it goes by and excites the insides, which in turn give off light, more like the way a water wheel works...the water is the same when it goes in as it is when it leaves...the only difference is its potential energy is lower on the way out after it has done some work. It needs two terminals to work because one is used as the inlet and the other as the outlet...light is just a byproduct of the flow thru the led.
aliasjanedoe (author)  seandogue7 years ago
I understand that. Where I got confused is why after the current goes through the LED that it needs to go back to the battery. Like if the battery is a glacier in your analogy that melts into the water which goes through the wheel. Why does the water need to then go all the way down the river and eventually back to the glacier and be refrozen and melted again? Why not just pipe it around and right back into the wheel? I guess my main mistake in describing what I mean was to call it a "single wire" LED. There's still the outgoing wire in my hypothetical, but it's build onto the LED itself, returning the current back to the in side (rather than that wire going back to the battery). Next time I ask a question, I should just draw a picture. I'm terrible at describing things.
aliasjanedoe (author)  aliasjanedoe7 years ago
Okay, I did draw a picture. It would seem I'm equally bad at drawing as describing. But anyway, this is my hypothetical LED.
led.jpg
lol, not as bad as many I've seen...

hmm...you're still missing something...people think of electrons like a fluid...that is, it makes a useful visualization tool, but what many fail to understand is that with electrons, you can't just strip them off the metal...they are conserved...so if they flow thru something, from somewhere, there needs to be a path to replace the ones that were lost (in this case, from the battery)

SO in your picture, the poor sot who has to trudge all the electrons back to the battery (near the "B" in battery) from the led is missing.

understood? they can't just go back along the same path., or they'd interfere with the ones going down the wire to the led.
aliasjanedoe (author)  seandogue7 years ago
they can't just go back along the same path., or they'd interfere with the ones going down the wire to the led.

That's why my imaginary LED has two in wires. Although okay, I'm seeing the flaw in that. So remove the two ins on the LED and put a resister there with two ins on it instead!

Or would we need to add a second battery into the mix as well, making it out-wire/battery2/wire/second-in on the resister? But I think I'm going to just give up on my hypothetical, because by the time I add enough parts to make it work, it'll likely be a bulky mess that's much more annoying than needing a second wire.

And I think I'm getting it now, thanks. So in my earlier picture (the one of the battery/LED/second battery set up), that's working because there's still the poor sot doing the trudging, so the electrons still have somewhere to go. Although it's a bad idea because they have no way to leave that second battery.
aliasjanedoe (author) 7 years ago
Somebody told me to just use a capacitor, and then I wouldn't need to connect back to the battery. So, can anybody tell me how a capacitor works? Any chance there's a guide with pictures?
gmoon7 years ago
You can connect LEDs together in series (although it's not the preferred approach):

+ --O---O---O---O--- -

But the more LEDs, the greater the voltage required. After just a few LEDs there would be a shock hazard...
Kiteman7 years ago
You need a complete circuit - current must flow through the LED to make it work.
aliasjanedoe (author)  Kiteman7 years ago
Yeah, but it only goes one way, doesn't it? So I guess I was more wondering why you need a second wire going back to the other side of your battery as opposed to like a wire built onto the LED itself that goes back into the LED on the other side. And wow, I just did a terrible job of describing what the heck I mean. Ya know, a loopy thingy. LOL! *facepalm*
I think what you mean is why aren't they configured like resistors, with the legs existing on the same line, rather than being parallel to each other, right?
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