1.  Field of the Invention
The present invention relates to musical instruments, and more particularly, to electronic musical instruments having means for automatically producing an arpeggio or similar note pattern. 
2.  The Prior Art
Automatic arpeggio systems for electronic musical instruments are known in the art.  Arpeggio systems, such as those disclosed in U.S. Pat.  Nos.  3,718,748, 3,822,407, 3,842,182; and 4,137,809 all in the name of Bunger; U.S. Pat.  No.  3,725,562-Munch, et al.;  and U.S. Pat.  No.  3,842,184-Kniepkamp, et al.,  typically rely on relatively bulky and expensive discrete transistorized logic circuitry.  Due to the expense, space, and cabling problems associated with the use of discrete components, it is sometimes not practical in these systems to provide each note with separate triggering logic circuitry.  Therefore, it was necessary to limit the arpeggio system to a portion of the keyboard or else to run groups of notes through the same gating circuit.  Thus, prior art systems have limited versatility. 
U.S. Pat.  No.  4,154,131 to Studer et al.  incorporates integrated circuitry based on transistor-transistor logic, overcoming some of these problems.  However, it is a complex design which is ideally suited for use in relatively expensive, sophisticated electronic instruments.  In contrast, the present invention is simpler, and can be utilized economically in relatively inexpensive musical instruments, including electronic organs.