I was euphoric when I got the signals to automatically change from Red aspect to Green as the train
approached, however now I can get them to also display the Yellow aspect with some programming of an Arduino. They will now look even more realistic seeing them display a yellow then turn to green after a short time.
Not only can they act as true automatic signals, I have them programmed to also be over-ridden and to go into manual mode - so if the train has to cross in a loop, I can display a constant Yellow aspect which then acts as a distant signal giving the driver plenty of notice of the Low Speed or Danger indication for the next signal - to slow down to enter the loop - just like in real life!
Furthermore, in real life, after a train has exited the block, these searchlight signals change from showing a Red aspect to a Yellow aspect, and then stay on this aspect until overridden by the central
controller.
I can also model this feature which is something extra that again adds so much to the enoyment. I remember as a young boy riding my bike to a railway crossing where these signals were present and to see them turn to green, drop to Red when the train went past, then when the train cleared the block, they would go to Yellow aspect and stay there. There were a pair of them just like on the layout.
Arriving at the railway crossing and seeing which one is yellow at the signal would tell me in which direction the last train came through. So, if the last train was an UP movement, and cleared the block, the signal would turn to yellow
and stay there.
If the next movement is a DOWN one, I simply switch it over, and the Up signal turns Red from Yellow, and the Down Signal turns Green from Red.The Signal will turn to Red when the train goes past the signal, then to Yellow aspect, then to Green Aspect, but if I am going to the outer loop i.e. going past a town and main yard and if there is a meet or cross, I display a Yellow aspect.The programming got tricky as I had to cater for bi-directional movements.
By using an Arduino, I save on two Detection Circuits I had made earlier which were used to change the aspect from Red to Green, and also the Signal Circuits that were made using a 556 timer that now become redundant.
On startup of the Arduino, one of the Automatic signals will show a Yellow aspect, and the other will show a Red aspect (opposing signal) - which one shows a Yellow aspect and which one show a Red aspect is purely random (however I have skewed it to show the DOWN signal a Yellow aspect more often as this signal is near my seat and looks really good from the control desk)
Rough Sketch:
I can expand on this and since there are three more Analog pins available which can be used for detection, I can do the same for the Approach Home Signals, although the Home signals do have a small LOW Speed signal as well....a project for another time.
