Stan et al. - why wouldn't just setting up a simple SPDT relay across the center rail to the outside rail do the trick? So when the center rail is energized, the relay (I'm thinking of an automotive or similar relay that has both NO and NC outputs) is closed and wired to the 'green' semaphore position/light. When the train triggers the 132 station relay, which in turn de-energizes the center rail, the second relay goes NO, which would be wired to the 'red' semaphore/position light. So in this scheme the semaphore is only an indicator, it is not involved in the electrical circuitry controlling the train.
So why does Lionel use a thermostatic switch for the station relay? Is it just to delay the firing of the relay? I don't think Gilbert (and then Lionel) ever used these types of relays in S gauge equipment. The Flyer semaphore, for example, has a solenoid in it - triggered by a somewhat fussy pressure-sensitive 'track trip' - that controls both the arm position and the power to the controlled section of track.
- Rich
