Ngineering - gooseneck lamps ?

[DKS]

I sure didn't see a link to the spec.

It was towards the right side of the page, marked "Data sheet."

They can't list the color temperature because they take a white LED and put a warm white lens on it or they do a dip.

There is a spectral distribution graph on the spec sheet; I'm sure the color temperature can be derived from this.

Warm white LEDs are usually made either by tinting the encapsulation material with a yellow dye, or by using a different phosphor on the LED face (the phosphors convert the blue/UV LED light into white light). Since the LED package appears to be clear, I would assume the latter, although the photo may not be of the actual device (typical "for reference only" disclaimer). I've never seen commercial LEDs that were "dipped."

Until warm white SMDs were introduced, I used Tamiya Clear Orange paint, either one or two applications depending on how blue the LED appeared.

[SkipGear]

The hardest part is learning to solder the LED's. I also roll my own in HO using 603's, small brass tubing and the small plastic bases that come with the Atlas hairpin fence kit. 402's are a little harder to solder just because they are harder to see and are a bit more delicate but one you learn the skill, they become fairly easy. Get some cheap 603's and practice. At first I would toast 1 in 3 but now, about the only LED's I waste are the ones I drop and can't find.



I've also gotten good at using existing plastic light fixtures and adding LED's to them. It's amazing how easy it is to hide magnet wire with a little paint.

[peteski]

I looked at the specs for the warm white 0402 LEDs DKS found in Germany.  I'm not so sure about them being warm white.  Their specs use xy chromaticity coordinates instead of color temperature.  It is not uncommon to use those specs instead of color temperature (however IMO, using those coordinates makes it more difficult to get a feel for the color of the LED).  The color coordinates for those LEDS are stated to be X 0.314, Y 0.347.

A hand chart for deriving color temperature from those xy coordinates can be found in http://www.cree.com/~/media/Files/Cree/LED%20Components%20and%20Modules/XLamp/XLamp%20Application%20Notes/LED_color_mixing.pdf (Figure 12).

According to that chart, the color temperature of those warm white 0402 LEDs is around 6400K. Not very "warm" since warm white is usually less than 3000K.  I might still order a sample of those LEDs to compare them visually to other 0402 LEDs I have.

As far as my secret LED tinting formula goes, the mixture is secret. 

[DKS]

Turns out the 0402 "warm white" SMDs I ordered in bulk from China weren't really "warm white" after all. But they're not cool-ish blue-white either; more like neutral white. So now I have many thousands of white 0402s I can't sell. Oh well, live and learn.

[VonRyan]

Turns out the 0402 "warm white" SMDs I ordered in bulk from China weren't really "warm white" after all. But they're not cool-ish blue-white either; more like neutral white. So now I have many thousands of white 0402s I can't sell. Oh well, live and learn.

How much for 100?


-Cody F.

[SkipGear]

Nothing wrong with neutral white. A little tamiya clear paint can fix that. What were you planning on selling them for?

[peteski]

Turns out the 0402 "warm white" SMDs I ordered in bulk from China weren't really "warm white" after all. But they're not cool-ish blue-white either; more like neutral white. So now I have many thousands of white 0402s I can't sell. Oh well, live and learn.

That sucks! I bet that next time you'll ask for a sample. 

[towl1996]

The hardest part is learning to solder the LED's. Get some cheap 603's and practice.

Good advice. I ebayed some China 603s, 100 for less than 5 bucks and that includes shipping. How is that possible?
Time to practice.

[peteski]

How is that possible?

They are made in China, and sold directly from China. Need I say anything else? 

[DKS]

They are made in China, and sold directly from China.

Yep, just like the white 0402 I have now in abundance. (Which is also why getting samples was out of the question.)