LED Questions
17194 cr points
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27 / M / Utah
Posted 4/30/14 , edited 5/1/14
Curious what is the best LED with watch battery or 9v?
Tips or list on what i need. Never have messed with LEDs before.
finishing Boosted Gear and think i need LEDS, but dont think timer would work.
Hope you all can help.
Please and thanks
69712 cr points
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Posted 5/1/14 , edited 5/1/14
(I PM'd you before I saw the topic, sorry! Adding info, and posting for others to see)

I went with ultra bright water-clear green LEDs (5mm). I bought mine off eBay, something like:
http://www.ebay.com/itm/100pcs-5mm-Red-Green-Blue-Yellow-White-Ultra-Bright-LED-Light-Bulb-Lamp-20000mcd-/141191784287 (variety pack)
http://www.ebay.com/itm/100PCS-Lots-Green-2Pin-ultra-bright-5mm-Water-Clear-Round-top-LEDs-Lamp-Light-/400702071517 (all green)

I used 9V for mine, so if you go with the second link, at http://ledcalc.com/#calc, I was able to type in 9 (input voltage), 3.2 (drop across LED, found on that eBay page), and 24 (current also on eBay page). It also asks how many LEDs you want to connect together, and shows how that could look. Once you have all that typed in, it can calculate that you'd need a 120 Ohm resistor. Lots of places sell specific resistors online, so just type that in and you can find what you need.

http://www.instructables.com/id/Simple-LED-circuit/ shows a really simple way to wire up the components, and explains what way to do so.

Adding more LEDs in a line like the LED calculator shows will only make things brighter if you just use a few. That is, 2 LEDs will be brighter than 1, but 8 LEDs will all be a bit dimmer than 1 alone would be. That's because the LEDs are set up in series - one after another. There is another way, called parallel, where you connect the LEDs in a different way. The LED calculator has an option for that, just click the "Parallel leds" link on the page, and you can see something like this:

That's how I did mine - it kept all the LEDs at the full brightness at the same time, but it's a little harder to put together.

Hope that helps!
Posted 5/15/14 , edited 5/15/14
As an expert on watch batteries I say stay away from them.
They only have 1.55v for silver oxide or 3v for lithium ion you could substitute with an AA or 2xAA without worrying about leaking acid or explosions.
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29 / M / NV, USA
Posted 5/15/14 , edited 5/16/14
Makoto pretty much covered most of it haha. I would recommend though looking into what jamesalot was saying, not so much on the leaking but battery packs in themselves have advantages. All depends on what your project is really, whatever battery type you go with your going to have to swap out at some point and I find battery packs though bigger a bit easier depending on location.
Posted 5/16/14 , edited 5/16/14
I take that back, AA leak, too. But they have a much higher capacity so if you use a capacitor in the circuit, you don't need as many!
Same goes for AAA, use AAA because they are skinny.
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Posted 12/22/15 , edited 12/23/15
"Year-end cleanup. Closing threads with no activity since 2014."
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