Hey guys, I got these custom LED Dwarfs.  they have red, yellow, green lights on them.  I got them from a Chinese supplier cheap.  no instructions.  just coded wires and a common black.  so,  I wanted to have them Trip on,  can you use the MTH realtrax 5" section with the wires that are under the track for this purpose?  I thought it would be completing the circuit of the LED.  But, how do you Run the Black common?  Ill post a pic of the dwarf and show you what I have when I get home tonight.  They are really nice looking lights.  I even have crossing signals that are basic LED lights come on, but I thought, I could use these MTH 5" sections to trip them. 

if you have done this, tell me how you do this with the MTH realtrax trip circuit. 

thanks

Chris