GB1274801A - Electronic chord selection device for a musical instrument - Google Patents

Abstract

1,274,801. Chord selection device. A. B. FREEMAN. 15 April, 1970 [23 April, 1969], No. 17970/70. Heading G5J. Any one driver 10 feeds an input to keyers 12, 13, 14 corresponding to the root, fifth, major and minor thirds, and seventh of the note operated, and either the major, or minor third, and possibly the seventh are inhibited from operating, so that minor or major chords, with or without the seventh are sounded. With the mode switch 26 in the position shown, operation of the drivers 10 gives rise to 6 major, and 6 minor chords, and the selector switch 16 may be used to give 3 distinct groups of 6 major and 6 minor chords. For positions 2 and 3 of the mode switch 26, all the chords are major, or minor respectively. For any setting of switches 26 and 16, the alternate musical key switch 24, which may be foot operated, interchanges the major or minor character of all chords. The drivers 10 may be interlocked so that only one at a time can be operated. The seventh of the chords is switched in or out by switch 29, and the thirds are selected via selector control 25, which is sensitive to signals from one or other of busses 17 or 18, depending on whether or not a voltage input is received from mode switch 26. Signals from keyers 14, corresponding to the root and fifth are fed via clamping diodes 35, 36 to a frequency dividing network 34 and are alternately clamped at a rhythm frequency by auto rhythm device 38 and RF control 37, so that root and fifth are sounded alternately at the output. Signals on leads 22 and 23 ensure that the root is sounded first when any driver 10 is pressed. A percussion envelope may be provided for the bass notes direct from auto rhythm device 38, which may also provide a rhythmic envelope to modulator 27, and tone shaping may be provided in the output circuit. A possible circuit for each keyer is shown in Fig. 2 (not shown), using clamping diodes to inhibit unwanted tones. In an alternative embodiment, Figs. 3, 4 (not shown) each keyer (51) receives signals from all drivers for which its tone may be required, Fig. 4 (not shown), and by earthing any of busses (56), (57) for thirds, or (58) for sevenths, the corresponding tone may be inhibited. With the mode switch (26) as shown, three sets of chords are selected by switches (59), (60), six chords being major, six minor, and operation of switch (26) gives rise to all chords being major. All major and minor chords may be interchanged by operating selector (25). The generator (68) may generate frequencies in several octaves.