Abstract

A model railroad cattle car sound effects system includes a speech synthesis circuit (FIG. 6) for "playing" selected cow voices stored as digital data in an EPROM (160). In a random mode of operation, a state generator (30) provides a pseudo-random count that is used to select among four different calm cow voices, one of which is silence. The resulting audio output is perceived as random contented cow sounds. A pendulum motion detector (FIG. 8) provides an indication of lateral motion of the system. An up/down motion counter (40) maintains a motion count reflecting the level of excitation of the system (and the cows). The motion counter increments responsive to motion, and decrements gradually in the absence of detected motion. A motion count of at least four invokes a triggered mode of operation, in which the counter output is used to select among four different excited cow voices. The resulting audio output imitates increasingly agitated cows as the motion count further increases.