Insulated rail and signal

Works fine in a TMCC environment. I like using 12-volt SPDT or DPDT relays, a bridge rectifier, and a 10-volt AC accessory source to power the relay.

1. Assuming your transformer includes a built-in 10-volt accessory port, the 10-volt "Hot" goes to one of the "AC" leads on the rectifier ("~"). The Common will pick up from the track common.
2. The other AC lead of the rectifier goes to the insulated rail.
3. The DC leads (+/-) go to the coil of the relay.
4. Your source voltage for the signal (can be 10-14 volts AC) goes to the "common" lead of the relay.
5. The "Green" power lead goes to the normally closed contact
6. The "Red" power lead goes to the normally open contact
7. The "common" from the signal is grounded.

When the wheels enter the insulated section, the AC flows through the rectifier and triggers the relay to change the signal.

I've done some variations on this theme to allow the mixing of Z-stuff signals with MTH signals. The red on Z-stuff signals is triggered by bringing the yellow wire to ground, so you have to wire the "hot" to black on the MTH signal; the relay common to ground, the green to normally closed and the red to normally open. It also makes it easier to use MTH two-head signals with Tortoise switch motors.