# LED questions



## lightsaber (Mar 27, 2018)

Hi all,

I plan on building an LED installation, and since I don't have too much experience with LEDs, I was hoping on some advice on how to get things right so I get the right gadgets and don't end up buying too much stuff that don't work.

Basically, what I'd like to do is illuminate a glass sphere (or other, more suitable see-through object) via a single LED diode from underneath. By attaching three LED in red, green, and blue I'm hoping that I can mix new colors. Will that work (i.e. if I turn on the blue and the green LEDs, will my spere turn yellow)?

If yes, how big a sphere can I possibly illuminate with a single diode so the sphere sill looks fully colored? Would this work better with a frosted sphere? Also, is glass/spherical the ideal choice for this, or are there other materials/forms that would perform better for this purpose?

Educated guessing welcome! Thanks!


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## tristar (Aug 12, 2008)

Just a suggestion, you'd probably be able to purchase LEDs which come with color control using a remote or an App, you could try those..


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## lightsaber (Mar 27, 2018)

tristar said:


> Just a suggestion, you'd probably be able to purchase LEDs which come with color control using a remote or an App, you could try those..


Sorry, I should have mentioned that this is for a bigger installation with multiple smaller spheres / glass objects. For just one large sphere your suggestion makes a lot of sense, but for what I have in mind, a color control LED for each sphere will be both too large and too expensive.


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## tristar (Aug 12, 2008)

Got it


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## SpywareDr (Jun 15, 2013)

lightsaber said:


> By attaching three LED in red, green, and blue I'm hoping that I can mix new colors. Will that work (i.e. if I turn on the blue and the green LEDs, will my spere turn yellow)?


That should be Red, Yellow and Blue.

Red and Yellow = Orange
Yellow and Blue = Green
Blue and Red = Purple
All three = Black


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## lightsaber (Mar 27, 2018)

https://en.wikipedia.org/wiki/Additive_color


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## SpywareDr (Jun 15, 2013)

https://en.wikipedia.org/wiki/RYB_color_model

?


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## lightsaber (Mar 27, 2018)

SpywareDr said:


> https://en.wikipedia.org/wiki/RYB_color_model
> 
> ?


That is for paint and print (as opposed to light).


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## SpywareDr (Jun 15, 2013)

Oh, okay.


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## Confounded Also (Aug 19, 2015)

lightsaber said:


> Sorry, I should have mentioned that this is for a bigger installation with multiple smaller spheres / glass objects. For just one large sphere your suggestion makes a lot of sense, but for what I have in mind, a color control LED for each sphere will be both too large and too expensive.



Might help to know sizes, viewing area, purpose, etc. There are higher power LED RGB units.


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## lightsaber (Mar 27, 2018)

Confounded Also said:


> Might help to know sizes, viewing area, purpose, etc. There are higher power LED RGB units.


I agree. Sorry, tried to simplify the setting for the question, but in the end, I omitted too much.

"Installation" is an exaggeration, anyway. We're talking about something for the desktop. 15-20 spheres, diameter maybe 1-2 inches each.


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## Confounded Also (Aug 19, 2015)

1-2" diameter is pretty small to work with. Frosted acrylic would probably be best, but I don't know where you'd find them.

A quick search for 'RGB LED discrete' finds a number of options including a standard 5MM T type package. It looks like the color changes with different voltages from 2-4 VDC, but I don't know how you'd accomplish that. Maybe one of the others can suggest something.

https://www.ebay.com/itm/100-5mm-RG...828638?hash=item4b2c8a9c1e:g:AZUAAOSwWLBaAYL4


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## lightsaber (Mar 27, 2018)

I could also go with three inches (maybe) - I just wasn't sure if a single led diode is strong enough to fully illuminate a sphere this size. Acrylic would work better / shine brighter because of lower density?

The way I interpret the ebay link is that you get a mixed bag with diodes of different colors. At least I can't imagine anything else.

By default, I'd probably have gone with 5mm flat-top diodes, simply because I assume the flat top would connect better with the surface of the objects I want to illuminate.

https://images-na.ssl-images-amazon.com/images/I/81vgBAT0V9L._SX482_.jpg


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## Wizmo (Apr 3, 2011)

*I would definitely go with the frosted spheres, as it would diffuse the available light better. You would likely need a high luminous output LED for each sphere, as it would only likely be visible in a darkened environment with a typical low power indicator type LED. :wink:

A good source for high output (ie *FREE*) LED's would be salvaged from a LCD TV screen with a damaged display. I've salvaged a few dozen broken screens and have accumulated a large number of "hobby" LED's for my experiments! :grin:

*


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## lightsaber (Mar 27, 2018)

Nice - thanks a lot for the replies.


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