Author Topic: Various white LEDs side by side as I said I would do ages ago .  (Read 755 times)

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up1950s

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Various white LEDs side by side as I said I would do ages ago .
« on: October 08, 2013, 03:03:32 PM »
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Finally got to do this . I bought some white LEDs to compare , and here is what everybody probably already knows . I painted the wires as they enter all my LEDs for a quarter inch or so to ID which is what  as most look the same . The colors mean nothing else . Thats why I never got to this sooner . Anyhow , maybe it will answer somebody's question , maybe not .








peteski

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Re: Various white LEDs side by side as I said I would do ages ago .
« Reply #1 on: October 08, 2013, 03:23:36 PM »
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Interesting info. So looks like unfortunately the best colors are sold by specialty hobby companies (which means those LEDs are probably way overpriced).  Personally I have graduated to using SMD LEDs in most of my models, so this info is of limited use to me.

I also question you powering all the LEDs in parallel.  These are all different LEDs, different brands and types.  So, they don't all have the same electrical specs (like Vf).  That means that each LED is most likely conducting different current through it (resulting in some being dimmer and some brighter).  That also affects the LED'sl color balance.  I think the test would have been better if each LED was powered through its own current limiting resistor, with those resistors chosen to send the same current through each LED. That way, you could have for example 10mA passing through each LED.
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DKS

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Re: Various white LEDs side by side as I said I would do ages ago .
« Reply #2 on: October 08, 2013, 04:34:36 PM »
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That also affects the LED'sl color balance.

Color balance shift while varying current is minimal. I've found most white LEDs to be close enough in spec that this test is useful. It's possible to find white warm LEDs in bulk on the Bay for pennies apiece. And since I use 3 and 5 mm LESs for buildings, this is again useful. I only use SMDs for particular effects where small point sources (such as street lights) are required.
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TiVoPrince

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Re: Various white LEDs side by side as I said I would do ages ago .
« Reply #3 on: October 08, 2013, 04:45:31 PM »
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Using
pots to 'dial in' the optimum resistance for each LED seems a great option.  This gives every product its best chance.  Adjusting to a nearby resistor common value for a real world experience.  Cost vs. quality is also a consideration.  If I need a few, cost may not be too big a factor.  But, outfitting a fleet is a different story...
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VonRyan

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Re: Various white LEDs side by side as I said I would do ages ago .
« Reply #4 on: October 08, 2013, 05:06:37 PM »
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Reading this on my iPhone 5 with a freshly cleaned screen, I find that the LED that is marked as being in third place to be the one that is the whitest.
Of course, I find that making all the lights uniform on an entire layout detracts a certain degree of realism since there are so many factors in our world that effect light.
I also still like the look of the light given off by the Minitronics 1.5v incandescent bulbs.
If I were to be picky to the highest degree, when lighting a project, I would choose an LED that gives off the light that looks closest to some form of prototype of what is being modeled.


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mmagliaro

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Re: Various white LEDs side by side as I said I would do ages ago .
« Reply #5 on: October 08, 2013, 05:38:00 PM »
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Not all golden/warm white LEDs that look as good as those 1st and 2nd place ones are expensive ones sold by specialty hobby companies.

Look on eBay under golden sunny warm LEDs

Also, the LED-Switch ones, which are really nice, aren't too bad.  You can get 25 for about $12.
LED-Switch also has some really small conventional-lead LEDs that are only 1.6 and 1.8mm.  They are the smallest
ones I've ever found that are not SMD.