ok thanks, I'll adjust my wiring to the common ground next time I get a chance.
One question, if I have a Lionel Fastrack Operating track hooked up to the constant voltage would it work at 9v? The manual says 10-12 v to operate, that is why I was using the C & D post combo.
Also, if I follow your instructions above I'm going to use a multimeter and mark my transformer at 17 / 18 V since that combo you mention above can go to 19v which is above the max Lionel recommends for Lionchief engines.