Good quality warm white LEDs, the classic 3mm diameter with a domed lens, have become scarce as hen's teeth. I used to like parts from Richmond Controls, but they were expensive. They cast a nice beam but with a green ring around the outside. Today they are not available.
They were perfect replacements in AtlasO SW headlight fixtures for both illumination and curved simulated glass lenses. They would also work in Red Caboose GP9s after removing the clear plastic sprue from the headlight. If used I would suggest wiring a pair in series and using at a minimum a 2K ohm resistor; at that value you will get flashlights suitable for night ops. With Loksound decoders each function output has a dimmer function, which can dim them fairly well but limits the slow on/off simulation and can cause strobing with some digital cameras when shooting video.
Recently I found better replacements for the now unobtanium Richmond sunny white LEDs. These are about 3000K color temperature and produce a nice beam pattern for O scale diesel headlights. They are honking bright! The latest batch I received have a hint of a green ring but it isn't bad.
LED production comes and goes. Sometimes a particular model may only last one year. This particular one appears to be only available from Digikey.
1516-QBL7IW30C-WW-ND QT Brightek (QTB) / QBL7IW30C
Currently 1-19 cost $0.59 each. 10-99 cost $0.39 each. 100-999 cost $0.258 each. At the moment they have over 9,000 in stock. Given the cost of shipping it is worth ordering a couple dozen at a minimum.
All the best,
Bob
