Patent ID: 9449590
Filing Date: 2016-09-20
CPC Classification: A63H,G10H,H04R,H04S

Claim Text:
1. A system for use in a model railroad locomotive, comprising: first and second track nodes for electrical coupling to a model railroad layout track; power supply means, coupled to the first and second track nodes and arranged to receive power from a Digital Command Control (“DCC”) signal on the track, for supplying power to circuits on board the locomotive; a microprocessor coupled to the power supply means, the microprocessor including or coupled to a memory storing sound data, and the microprocessor configured to read the sound data from the memory and generate digital sound samples responsive to the sound data; a variable current sink coupled to the first and second track nodes and coupled to the microprocessor to sink current from the track in an amount responsive to the digital sound samples, thereby passively conveying sound information from the locomotive to the track for detection by a controller coupled to the track remote from the locomotive; and synchronization means coupled to the first and second track nodes to receive the DCC signal and coupled to the variable current sink for synchronizing the variable current sink to the DCC signal.