reversing track signaling

[wondering]

I have a completely isolated section with a separate transformer from the rest of the layout.  I'd like to wire a light that would show me if the two transformers are set for the right direction. I.E> when train reaches the section a light comes on indicated the direction switch on the other transformer is set in the right direction.  Can someone show me how to do that?

Thanks

[Hunt]

Click Here to view video

Adopt this simple DC polarity detector to meet your need.

[wondering]

That's cool and it looks simple enough.  The next question would be: how and which rails on each section do I connect the red/black wires to?
I.E:  both outside rails from each power pack,or outside rail from one pack to inside rail of other pack?
thanks

[Hunt]

Use a detector for each power pack.