Running TMCC On A Large Layout


The Liberty Hi-Railers use TMCC for train operation.

TMCC can provide challenges when operating under demanding conditions such as those found at Train Shows.  Some of those challenges include:

  • Multiple clubs operating TMCC on the same frequency (TMCC has only one frequency!)
  • Radio interference from DCC, RC Models, ham radios, FM Live broadcasts, or just about any other source one can imagine.
  • Temporary nature of the layout which includes many connections between sections. (Connections are not much of a problem for power propagation but for radio signal propagation it is a whole different ball park!)
  • Less than optimal Earth Ground from power source.
  • Large size of the modular layout.
  • Inherent complexity of Analog Radio Signals!

As you can see, there are quite a number of gremlins that can affect your TMCC performance adversely.  The symptoms of TMCC problems are typically a flashing headlight which indicates poor TMCC signal strength.  Often this goes with an engine stalling for lack of signal.  In the worst case an engine might take off at full speed because it believes it is running in conventional mode on 17 volts! Furthermore the problems are typically not just a single factor as described above, but some combination.


Accordingly we have taken a variety of steps to act as countermeasures. Some elements of being at a show are out of your control, others you can modify and some require fundamental changes in the TMCC equipment by the train manufacturers.

  • Use a single extension cord to plug the entire layout into 1 outlet.  Use a three lamp outlet tester on that outlet.  This can detect a bad ground or other power supply problem. Also by having the entire layout plugged in to one outlet you avoid any possible problems with outlets not being in phase with each other.  (This can happen in a large auditorium!)
  • Plug the TMCC command base into a power strip without a surge protection circuit.  Power strip surge protection circuits tend to drain off your TMCC signal.  You can plug the non-surge protected power strip into your extension cord.  Then plug the TMCC command base into that power strip.  Also plug a surge protected power strip into it to plug your transformers into.
  • Dual power taps.  We now route the transformer outputs to two long six wire cables.  Each cable plugs into the layout at opposite corners.  This helps ensure we have a good injection of the TMCC signal in two places. (It does not hurt our power distribution either!)  The end of each Power cable is a Y shape with a male and a female 6 pin connector. This way we can put power in between any two modules with no special wiring.  We just insert the power Y between the normal two six wire connectors on the modules.  This also has the effect of directly supplying power to 4 modules.
  • The end of each tap is a male and female 6 wire module connector.
  • Place the TMCC command base closer to the center of the layout.  This minimizes the distance that any CAB1 remote will be from the command base.  We used to place the command base on the far end of the layout.  This meant that you would have fairly long distance from the opposite end of the layout.  We now place it midway on one of the long sides.
  • Run an earth ground wire around under the layout.  We have a long 14 gauge cable that plugs into the third prong of the outlet (Earth ground NOT the black transformer terminal!!!) 

    This helps reduce external radio noise.  To build the plug we bought s prong replacement power plug and wire only the ground prong to our loop of wire.  The other two prongs were taped up and not used.  Actually we have two ground wire connected and we run them in opposite directions.  They overlap a little on the opposite side of the layout.  This gives us shortest path to ground from either direction.
  • Have a printed list of the engine id numbers your club intends to use.  Bring a few copies, you can exchange them with other clubs at the same meet to avoid disasters!
  1. Plea #1 to Lionel - Please change the cabs and command bases to have a selection of frequencies to operate on, or else add a system ID number to differentiate multiple systems.
  2. Plea #2 to Lionel - Please add a 4 way mode switch to all TMCC engines, the four modes are TMCC Program, Run (automatic select), Run Conventional Only, Run TMCC Only.


We used the cabling suggestions at the 2004 East Coast Hobby show, the February 2005 Greenberg's show and the 2005 East Coast Hobby show. For those three shows we experienced zero issues with TMCC signals.

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