FAQ:Why use a uni-polar signal instead of DC with a superimposed signal?

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DCC Categories DCC, Power, Multifunction Decoder
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There are a number of advantages to using a uni-polar signal: The DCC signal is the power, instead of being superimposed on the track voltage. If you can get power to a locomotive, you can control it. Wiring loops and reactive losses, which can cause problems in carrier systems, do not cause problems with this technique.

  • The track stays cleaner, there is no polarized electro-plating action as there is with DC systems.
  • The reduced space charge that forms around the rails reduces the attraction of contaminants.
  • The uni-polar signal simplifies the design as reversing the locomotive on the track has no effect on how it sees the signal.
  • Simplified multifunction decoder design.
  • It is possible to control an unmodified locomotive - see the section on compatibility for more details.