WHAT COLOR IS WHITE?!
This research was borne out of frustration. I had replaced a dozen lights on various
locos and the engine terminal ended up looking like a Christmas tree. Was fed up with what people called 'white'
LED's and set out to sort out a solution.
Soooo…. Over the past year (OK, longer), the GNW has gone a bit crazy
trying to find SMD LED's that that that right color to them to simulate
the 'halogen' white color of diesel
locos produced since about the 70's. We
took all the different SMD LEDs collected over the past
year and put them together on a PC board test strip in a way that clearly shows the differences between LEDs and colors.
There is also a spreadsheet that summarizes the source, model number, color and other info:
Note that the strip is two rows of about 20 columns. The spreadsheet is set up with column references counting from left to right, 1 through 20.
Of course, colors are hard to reproduce, so I tried as best as possible to get a couple photos that capture the actual color of the LED. In reality, they are all VERY bright. So if you are looking for that 'glint' off the railhead, any of these will work fine. I also included a couple standard colored LEDs for color reference - blue, red, yellow and green. That should help with determining standards. Also I included one photo more underexposed to exaggerate the color shifts.
Another point to make is the colors on white LED's are really sensitive to current flow. In other words, expect some color shift in these as the current drops or increases. For the sake of commonality, all LED's are powered through a 1K resistor, with the exception of the 5050 LED which is around 800 ohms. Note that 0603's are going to be uber-bright with 1K, but many of the PLCC2/3528 LEDs are just getting into their groove at that current flow. All LED's are powered by a common 12 VDC power supply. I used SMD resistors for all LEDs except, again, the 5050. All in all, 34 LED's are compared. Yes, the board does get nice and toasty!
If you have pulled up the photos, let me share a couple
Love the 0603's for small areas. However, for headlights, I am preferring the PLCC2 packages. I installed a few 0603s directly in the headlight casting and am finding the rectangular appearance of the LED annoying. With a PLCC2 package, it can be easily installed behind and fully cover a typical light tube. That said, I have had a blast installing 0603's as step lights on a few locos. Wow, does that ever make a difference! A lot has been shared about 0603's, and they certainly are great for where they are appropriate. But don't forget some of the bigger brothers and sisters of the 0603 - they have their place too!
How hard is it working with these beasts? Frankly, if you can solder to a typical solder pad on a decoder board, you are more than set to get into SMD's. I only lost 2 LED's in building this board: one flew away when I knocked the package as I was dropping out the LED, and the other I accidentally broke when holding it down with an Xacto knife. Trick with 0603's is getting leads onto them. It's really not hard once you had some practice. You will need #34 or #36 ga magnet wire for the leads, regular or even "DCC hookup" wire will be too big to solder to the pads. There is a great YouTube vid on how to solder to these little buggers:
I also included a few LEDs coated with Tamiya clear coats; 0603 Warm Whites and 0603 Bright Whites. The bright whites are VERY blue, so coating them just added the coat color to a blue color. That said, the warm whites took the coat remarkably well, making very warm colors.
A couple other points are:
· "Warm white" is not always the same. I was absolutely disappointed with SatisLED's WW - it has a very yellow-green hue. In contrast, Ebay seller HiTechLEDWorld's WW 0603 is fantastic. Scan through the photos and you can see most are labeled warm white, but they are all definitely different in color.
· Miniatronic’s T-1 “YeloGlo” has a definite green hue. This is actually what started this whole program – I did not like it. The first replacement LED that I liked is shown just to the right of this one – an LED from TOPBRIGHT88, another Ebay seller. Much better price and color.
· Included in the test setup are three "temperature rated" PLCC2 LED's from DigiKey: one each rated at 2700K, 3000K and 3500K. I put one of those 2700K LED's in my steamer and, wow, it looks good. Like an older incandescent lamp.
My personal favorites:
Anyway, rambled long enough now. Take a look and let me know if you have any questions. Hopefully this is helpful to people. Standard disclaimer – I have no interest in any of these sellers or companies. I just got tired of buying LED's for my locos and not liking how the color turned out. As it turned out, I probably contributed to the wealth of some of these vendors more than I intended. So, might as well share what I learned.