Warm White LED color accuracy

[Canuke]

How many of you have been working with warm white LED's, particularly in model railroad/miniature applications?

The only ones I've seen have been in Christmas light strings and a few in model houses for under the tree; I have found that all of these are a bit lacking in red, and as a result look a bit more yellow than "warm" to me.

However, I ran across a wreath at Lowe's that has warm whites that look just about dead on. If I were doing model railroads, those would be the one's I'd use in lieu of the "grain of wheat" bulbs.

 

[jtr1962]

I've tried a few specifically for the application you mentioned. The BestHongKong warm whites seem to be better than the LCKs (which are somewhat greenish). I haven't tried the Light Of Victory or Jeled warm whites yet.

I've found that I had to do an extensive amount of testing to find suitable LEDs for model railroading. Even where I was seeking to imitate fluorescent or HID lighting I found that most white LEDs were too blue. At first I combined the whites with ambers in various ratios. This gave a satisfactory result but the light didn't mix perfectly evenly, and it was hard to get a consistent tint due to variability. Eventually I hit upon the BestHongKong UWLC series whites. These gave a consistent tint in the 5000K area and so were suitable for my purposes.

Trying to imitate incandescent lighting proved to be a bit harder. As menitioned, the LCK warm whites weren't that great. The BestHongKong were better, but still somewhat lacking. I tried adding some red LEDs. This seems to give a great result, albeit with a slight color mixing problem. The ratio depends upon the relative brightness of the reds and warm whites, but if chosen properly the combination looks just like regular incandescent lighting. Note that for comparison purposes I used regular household incandescents, or my 12V, 20W halogen desklamp, rather than the much lower color temperature grain of wheat bulbs. Those are unsatisfactory even to imitate incandescent lighting, as strange as that sounds. I'm hoping eventually my testing will stumble upon a warm white which doesn't require the addition of reds. The Cree XR-E warm white I tested looks quite good, but it would obviously be overkill in this application. If something similar existed in a 5mm LED, it would be perfect.

 

[Julian Holtz]

I remember someone here painted his LED with a yellow/ rose sharpie pen, ans was delighted about the result.
Perhaps worth a try.