Patent ID: 7769478

Claim:
A sound system for model trains and accessories, the system comprising: an electronic sound chip for storing digitized sounds, the sound chip containing a sound processor for producing sound from at least one of the voice channels in the sound chip; a microprocessor comprising an internal comparator operating as a voltage controller oscillator, the microprocessor controlling sound chip operation using the comparator to detect variable DC offsets, input by a user, by a voltage to frequency conversion and measurement process and thereby activating one of the voice channels in the sound chip, which the microprocessor self-calibrates on an initial power on of the system to measure a base frequency which is locked internally in a non-volatile storage for later comparison by the comparator against DC offset to frequency conversion; wherein an opto-coupler shuts down a power amp to preserve power to allow firmware to remain operational in both the microprocessor and the sound processor; permitting sound generation to resume through brief power interruptions and to prevent “kick-back” that could create a malfunction of standard reversing electronics in locomotives.