Details available here, DFPlayer Mini MP3, downloadable manual.
This particular MP3 player was selected based on the following, minimum connections to activate the player, economical and readily available from a variety of outlets, standard Micro SD, conventional and easily sourced MP3 sound files, 8 ohm and up to a 3W amplifier.
Connection diagram, 5V & GND supply, speaker connections, and three means or methods to operate.
Stripboard PCB layout, 5V power supply, power supply input either from a DC or DCC source.
Three push buttons or three connections for activation via three Reed Switches.
Alternatively a combination of push button and Reed Switches for activation.
Alternative Stripboard PCB for use for activation with the Function Outputs from a Multifunction Decoder or from a Accessory Decoder.