To control a switch automatically with a 1 channel switch decoder, following circuit can be used.
You will need 2 track contacts, a 1 channel switch decoder and locomotives with mounted magnet on the gear side.
Here is a diagram of how everything should be connected:
In this combination, the switch is automatically moved into the correct position before leaving the reverse loop.
Note the polarity of the contact inputs.
Please connect both brown wires to each outer contact input pin.
Please connect the track contact and the switching decoder according to instructions.