What do you want the signals to do? Mine are simple turnout position indicators for the track ahead. It's not particularly prototypical, but it gives me illuminated signals that are useful to me. More complicated signals are available, but the circuitry gets more complicated.
Signal control isn't particularly scale dependent. The same systems work for N gauge that work for O gauge.
If you have a particular model of a signal you'd like to connect up, let is know what it is. Also it sometimes helps to know if you're running DC or DCC.
You joined in 2013 and this is your first post? Cool, and welcome aboard! . You may notice that your first few posts don't appear right away. They're being reviewed. When there are huge flare-ups over modeling graffiti, it's an easy solution to a pretty much non-existent problem.
It takes an iron man to play with a toy iron horse.
Looking for n scale track electric signals especially gantry bridge.