Locomotives on DCC layouts require a decoder to be fitted to control the motor direction and speed. Additional functions are available on most decoders, usually function 0 being used for directional lighting.
DCC Ready locomotives are fitted with a plug-in socket for a decoder, check which type is needed for your locomotive, usually this is shown on the end of the box and operators leaflet.
Sockets for 8 pin decoders were commonly fitted to OO and HO gauge models. Heljan and Hornby models still currently use this socket.
For N gauge a smaller 6-pin socket was designed, along with a small-sized decoder. Bachmann Graham Farish and Dapol N gauge models have 6-pin decoder sockets. Recently Bachmann have designed small OO locomtoives (eg the BR 03 shunter) with sockets for 6 pin decoders.
21-pin connectors are increasingly common in OO models by Bachmann and Dapol
Locomotives without a socket can be fitted with decoders or fitted with a socket by re-wiring the locomotive and soldering the decoder wires in the circuit. Reference to the Peco Shows You How booklet is recommended for guidance.Sound decoders have their own section - click to transfer.