Last Updated: 27 August 2021
Alternating Station Circuit
Imagine a train is stopped in the isolated track block on Track 1. Another train enters the circuit from the left on Track A. The first track switch (W1) is set to straight, and so, the new train continues onto Track 2. The train triggers the lower 17100, and the 12010 moves W1 to the turned position since the control wire is connected to the “up” side (D) of the
lower 17100. At the same time, the 12030 disconnects power to the isolated track block on Track 2, and it connects power to the isolated track block on Track 1. The train on Track 2 will stop as soon as it crosses into the isolated track block. The train waiting in the isolated track block on Track 1 will start and proceed through the manual track switch (W2) onto Track B. (The
setting on the manual switch is not important. See Using Manual Switches for more information.) The train now waiting in the isolated track block on Track 2 will stay there until the train that was on Track 1 returns. Then the train on Track 2 will be released and the train on Track 1 will be held. If you install this circuit in an oval layout, this process will keep repeating
itself… forever. One train will leave the circuit, circle the layout, return and stop. The other train will leave the circuit, circle the layout, return and stop.
Alternating Route Circuit
Two 17100 Track Contacts are connected to an electric switch. That electric switch controls which route the train takes. The 17100s are mounted at the end of each route. When the train crosses the 17100 at the end of one route, it sets the electric switch for the other route. When the train crosses the 17100 at the end of the other route, it sets the electric switch for the original route.