On freight trains, it can be more appropriate to install the sound decoder into a four wheel van as illustrated by this Hornby van.
The speaker has been installed pointing downwards over a number of holes which have been drilled in the van floor to allow the sound to exit and bounce off the track. It is held in place by double sided tape which was also used to locate the decoder.
A 200 microfarad stay alive capacitor has been fitted to ensure that the sound is continuous over dirty track, dead frogs, etc.
The lights and function outputs were not used in this installation so the yellow, white, blue and purple leads were placed into a piece of heat shrink tube for possible future use.
The last step is to set the DCC address for the sound trailer. It is suggested that you use an easily remembered code, like 99, for the sound trailer. Each time you wish to run it with a locomotive, you can then set up a double headed consist for the locomotive code and 99. Alternatively, you can change the sound trailer address, each time, to be the same as the selected locomotive.
The benefits of a sound trailer apply just as much on DCC layouts as much as on DC. A limited number of DCC sound decoders are available but are expensive and the idea of converting all one's locos to sound is well beyond the pockets of most hobbyists.
Installing the MyLocoSound decoder into a van or coach provides a flexible and very economical way of running a large number of steam locos with sound.
The photo below shows typical installations in Hornby four wheel and bogie baggage vans which can be run, realistically, behind a wide variety of British locomotives. In Australia, a water carrier can perform the same role.
