Hi Jon
I know that you have been building signal for a very long time now so please do not take what I'm going to say the wrong way.
I understood that all semaphore signals has one glass in red and one in blue due that being illuminated buy a oil or electric light being yellow in colour did not effect the red but when behind blue glass was seen as green buy an approaching train?
I know that you use white led to illuminate the your signals but would it not be more correct to use a yellow Led and clear red & Blue?
I'm not trying to nit pick as I think your work is great.
Pete