For background, I had purchased individual sealed LED units (can't replace the bulb) for the nav lights on my boat in order to clear the deck space in the pulpit (my light was a deck-mount combo). A lightning strike this summer while the boat was on the hard took out most of the replacement LED bulbs I had in the lights (anchor light, stern light, etc.), including the two sealed LED nav light units. Since I now had to replace the whole fixture, I decided to buy standard (incandescent) fixtures and use replacement bulbs for ease of replacement down the road. So far I only have the green (the red wasn't available at the same time). I then bought a batch of cheap replacement LED's (31mm festoon) and set about replacing the incandescent bulb.
First glance, LED bulb is brighter than the incandescent, as expected. But it also makes the light look teal instead of green. The LED is cool white (warm white was not available). Also, I noticed that the contact caps on the two ends of the LED are not as secure and rigid as the incandescent bulb. The end cap would bend over (bow its head) when pressed into the fixture. I anticipate that this would eventually result in broken contacts and damage. So here's what I did to fix the two conditions:
Here is a pic of the two bulbs side-by-side.
=First I went to The Physics Classroom (physicsclassroom dot com) and read about light, particularly the two pages called Color Addition and Color Subtraction.
=Since yellow film will filter out the blue light, I bought a roll of cheap yellow cellophane wrapping paper (because it was cheap).
=I wrapped the LED bulb in yello cello to get the blue out of the light passing through the green lens. Tested the bulb with various numbers of layers to determine the fewest number of layers that would give me a solid green color. For my cheap yellow cello, that was five layers, as the yellow color is very light. It may vary for other types of cellophane or gels. (I looked into using a true color gel for light shows, but they were expensive, and I was still experimenting.) I made a long strip of yellow cello like a piece of tape and wrapped it around the bulb, attaching it on the back of the PC board at the beginning and the end.
This picture shows the bulb wrapped in yellow cello.
That picture also shows the way I fixed the weak bulb structure - hot glue. I just shot hot glue into the four "holes" at the ends of the bulbs the best I could (nothing perfect) and allowed them to freeze. Hot glue freezes pretty hard, but maintains just a touch of flexibility (for vibration resistance). It seemed to work very well on the bench, as the bulbs no longer distorted when pressed into the fixture. Time will tell if this will hold up in service.
Last picture is the color change from the original teal (bottom) to the now clearly "green" color (top) of the wrapped bulb. (Physics is some cool stuff.)
I hope this helps someone.
I'll post the same results from the red fixture when I get it.
