Q: Can I use Transponding with existing Digitrax decoder installations?
A: Once transponder receivers are installed on the layout, you can run any transponder equipped locomotive.
All current production Digitrax decoders are transponder equipped.
Older Digitrax decoders models without transponders and decoders made by manufacturers that don't support transponding can add transponding by installing a TL1 or TF4 to the locomotive.