The benefits of a sound trailer apply just as much on DCC layouts as on DC. A limited number of DCC sound decoders are available but are expensive and the idea of converting all of one's locos to sound is well beyond the pockets of most hobbyists.
The method of installation is the same as for DC except that a DCC decoder is also required. Any low cost decoder will do provided it has:
- A spare function output to operate the horn or whistle and
- No back emf control or the ability to turn back emf control off.
A Hornby R8249 decoder is suitable as is any Digitrax or MRC decoder and the connections for the Hornby unit are shown below:
Back emf control is something which decoders use to control motors. In a sound trailer there is no motor. Therefore back emf must be turned off otherwise the soundcard will not work properly. In the Hornby R8249 decoder, this is achieved by setting CV10 to a value of 1.
In the diagram above, the green function 3 output has been connected to the soundcard H1 terminal to operate the horn or whistle.
To run a loco with sound, you attach the sound trailer behind the loco and set the soundcard decoder to the same address as the loco. The two then run as if the train was double headed.
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