GB1080936A - Improvements relating to electronic musical instruments - Google Patents

Abstract

1,080,936. Electrophonic instruments. SEEBURG CORPORATION. June 22, 1965 [June 26, 1964 (3)], No. 26252/65. Heading G5J. In a repetitive instrument used with a main instrument, a pulse generator 11, Fig. 1, operates at a multiple, e.g. twenty-four times the basic rhythm frequency, and feeds a divider 14 consisting of scale of three and binary stages. The outputs of the divider or counter 14 are connected to a matrix of diodes, resistors and capacitors, Fig. 2 (not shown), to provide various logical circuits. The AND circuits (27) and OR circuits (37) are connected to inputs (30) and (38) respectively of a selector switch (28), Fig. 3 (not shown), which controls the operation of rhythym instrument stops (29) feeding an audio section (31) which also has a melody input (32) and pedal keyboard (33). Certain of the pulses in the recurring sequence are selected, Figs. 1 and 5 (not shown), by employing the correct waveforms from divider 14 in combination, together with a differentiated pulse. In order to keep the instrument in time with the player, a pulse is fed to terminal 58, Fig. 1, each time the pedal board is operated. This pulse is gated by the output of a two-state trigger pair 62 so that it is only effective when it occurs just before or after the expected time of occurrence which is determined by the connection between the pair 62 and the selected outputs of the divider. The gated pulse causes a relay 59 to operate and feed an output from the divider 14 to an integrator 41 consisting of a resistor 63 and capacitor 42 in a feedback amplifier 51, 52. The resulting potential on the capacitor is applied over emitter follower 44 to control the frequency of operation of uni-junction transistor 55. By operating a switch 45, the frequency of the oscillator is held at a fixed value. In a modification, Fig. 6 (not shown), two ring counters (120) are employed to feed a diode logic matrix (125), the counters employing transistors, tunnel diodes or neon tubes.