You need a relay.
In layman's terms the MTH crossing gates have 2 input wires that tell it what to do. Yellow wire tells gates to go down (and start flashing), White wire tells the gates to go up (and stop flashing when gates reach top).
The insulated rail method only provides one signal. A relay converts this into two signals to drive Yellow and White. That's what the ITAD does in the MTH diagram; there's a relay inside it that drives Yellow when a train is detected or drives White when train is gone.
There have been dozens of OGR threads written on this. It's hard to point you to one since everyone seems to have a slightly different setup or requirement. Do you have Accessory AC voltage from your train transformer or do you really need to run it off track voltage? Are you running conventional or command control?
