I have been reengineering my 1950s American Flyer train for nearly 10 years. Adding updated Smoke for steam engines and 3 d Printing all wheel pick up trucks for tenders and engines. For several years I have tried many methods for producing sounds on the engines. We use to have industry systems but they became super expensive then eventually disappeared. A $25 Sound Board became a $350 Sound and Control System. So today I and engineering a Next Generation S Scale Control system using lots of IOT, Arduino and 3d Printed housings. I need a combination of technology that can support an Operator with a remote device likely ESP8266 MicroController with WiFi functions, that can invoke a sound file from a sound board in the Train Engine, which is powered either with a Transformer providing 5 to 15 VAC to the Train Track. That power needs to be picked up reliably and transformed into DC and regulated to drive Arduino Boards and the variety support functions. DC Motor Drivers, Digital Sounds, LEDs and Steam Smoke heaters and fans.
I have yet to find a Sound board that can operate reliably in these conditions and power supply methods. We build and test al the time with samples or test parts. searching the best solutions. I would like to find users/makers that play in similar environments and have found sound solutions that work for them. And Anyone aware of more options than we have discovered today. I can but parts, build test sets and provide feedback. Once the solution is found We will build it out as a production offering to the S Scale community. Our sporadic progress is shown on Face Book at Frankentrain Laboratories.