Reversing unit question. Has anyone used one of TCH technologies reversing units or any other reversing unit to accomplish this? It says it can be used to make a reversing loop automatic. I have purchased 2 units and can not figure out the wiring. Im running conventional 2 rail DC. The engine will go into the loop but will not exit do to the polarity change. I have had atlas switches hooked up in the past and it was working, but wanted something automatic. Is this even possilble with DC wiring?