Abstract: An electronic musical instrument including a compact, portable pedal board and a storage case for the pedal board and for the electronic components of the instrument is disclosed. The pedal board includes shortened foot pedals having a low profile and a very low throw for activating control switches for the electronics, whereby the pedal board can be used in conjunction with a piano or with other instruments. The low throw is obtained through the use of a guide channel mounting arrangement for the pedals and by the use of pressure sensitive switching.The storage case receives and secures the pedal board and also provides a housing for the tone generator, amplifier and other electronics controlled by the pedal board. A control panel door on the end of the storage case is adapted to receive a control panel, and is hinged to the storage case so that it may be swung fully open to expose the control panel. The case may then be positioned on its opposite end to serve as a display stand for the control unit.

Abstract: An electronically controlled swell shutter operator for pipe organs includes an electric motor driving a speed reducer whose output is connected to move the shutters of a pipe organ swell chamber, in order to control the volume of sound heard by the listeners. A swell pedal controlled by the organ player operates a first potentiometer and establishes a first voltage of a given polarity, the magnitude of which represents the exact position that the shutters should be in. The output of the speed reducer operates a second potentiometer which establishes a second voltage of a polarity opposite to that of the swell pedal potentiometer, the magnitude of this second voltage being dependent on the position of the swell shutters. A system of integrated circuit comparators compares the above-mentioned first and second voltages to produce an error signal.

Abstract: In an electronic musical instrument, such as an electronic organ, the speech characteristics of Vox Humana and similar reed organ pipes are simulated by applying a repeating series of pulse groups separated from each other, which groups each contain a short sequence of two or more pulses, to a sharp cutoff low-pass filter for converting the series of pulse groups into a sound producing signal simulative of the sound signal produced by a Vox Humana or similar organ pipe. The repeating series of pulse groups is obtained by nonlinearly combining square wave tone signals from two or more different octaves of a conventional phase-locked tone generator. The synthesized repeating series of pulse groups, one series for each note of the instrument, are applied to a single low-pass filter, or grouped and applied to a small number of filters.