spoon059 wrote:
Gdetrailer wrote:
The original incandescent light bulbs used in markers ARE NOT "colored" so really a white LED could be used. The only real reason to use colored LEDs is they tend to be much cheaper to manufacture than white LEDs and hence are cheaper to purchase.
An incandescent bulb creates a wide spectrum of light, including the color red or orange. A LED bulb creates one color. You can put a white LED behind a red lens, but it will be very weak because the white LED isn't producing the red spectrum of light.
Try putting a red LED behind an orange lens... won't be very bright.
Your “reasoning” as to how you arrived at your conclusion is flawed.
In order to GET “white” light you MUST have the proper combination in percentage of light of ALL THREE PRIMARY COLORS. These colors are RED, GREEN, BLUE.
You CAN NOT HAVE WHITE LIGHT WITHOUT THE RED COMPONENT, PERIOD.
This is a basic High School Science/Physics 101 thing that you should have had in High School..
Read this link to help you understand why your assumption is incorrect.
Mixing RGB Light to get White LightAnd from from
HEREand I quote..
"It is well known that red, green, and blue LEDs can be com-
bined to produce white light. This can be represented on a chro-
maticity diagram. The most common chromaticity diagram is
the CIE 1931 coordinate system
. However, the just no-ticeable color difference is not a constant length over
space.
By applying a linear transformation a new coordinate space can
be generated where the just noticeable color difference is ap-
proximately uniform."
Your flawed assumption is due to the AMOUNT OF RED LIGHT which is a smaller percentage of the over all light which the RED (or any of the primary colors) is LESS than the sum of ALL the light from the other two primary colors.
ALL primary color lights ADD to the overall brightness. Light is ADDITIVE.
The RED LENS FILTERS out the other colors (Primary and complementary) and only allows the RED to shine through..
I actually had to help my DD last year with her 8th grade SCIENCE project which was about this very subject of how you can get WHITE LIGHT from using INDIVIDUAL LEDs which are RED, GREEN, BLUE.
I can assure you over many years of repairing TVs that I have setup MANY CRT TVs from scratch by resetting the guns back to zero and bringing back up one at a time in order to achieve the proper ratio. The result when done correctly results in perfect white balance and that results in a correctly balanced black and white along with ALL colors of the picture.
To your “point”, using a purposely made RED LED of the same brightness of a white Led will result in brighter red, but it has nothing to do with the white LED not reproducing RED. It is about the ratio of red in a white LED vs a purpose made Red LED..
My point is ANY WHITE LED CAN BE USED since it MUST HAVE RED in order to make “white” light. RED LEDS are cheaper to make and therefore cheaper to buy if cost is your issue..
The advantage of using white LEDs is that you only need ONE type of LEDs to service RED OR AMBER MARKERS..
But my personal take away with my own experience with commercial made LED fixtures is they do not LAST as long as they should. Since they do not last you will want to BUY SPARES in case they fail while you are on a trip.
