A variable resistance device for a portamento performance on an electronic musical instrument wherein a conductive coiled spring is held by a supporting member and an elongate resistor is so held by the supporting member as to face the coiled spring at a small space. The elongate resistor is used to determine the output frequency of a tone signal generator. Depression of the coiled spring with player's finger causes it locally to contact the resistor, and the continuous shift of the player's finger successively varies resistance across the coiled spring and resistor, thereby providing a portamento performance.

The disclosure describes an improved digital oscillator for use in an electronic musical system capable of converting electrical tone signals into corresponding sound waves. The oscillator includes an adder, accumulator and multiplexer for selectively transmitting either a divisor number or increment number to the adder. The oscillator cyclically performs incrementing operations by using the increment number over a variable range established by the divisor number at the beginning of each cycle. When the modulus of the adder is exceeded, the adder generates a carry pulse and a remainder. The divisor is then added to the remainder before the incrementing operations begin again. A digital calculator automatically calculates the proper values of the increment and divisor numbers so that the carry pulses occur at a predetermined frequency.

A voltage divider device capable of providing any voltage in a preselected range of voltages, which voltage may be set by a touch of the finger is disclosed. The device includes a control element without frictional contacts and a voltage storage circuit controlled by the control element. A circuit including the device is described and embodiments of the device providing a visual indication of the setting of the device are disclosed.

A touch sensitive device is associated with at least one key of an electronic musical instrument such as an electronic organ, includes a layer of a pressure responsive, variable conductance material, and exhibits a switching action when subjected to pressure beyond a threshold pressure, any increase in pressure thereafter providing an increase in conductance up to a saturation pressure. The device may be used either as a combined switch and amplitude control or may be used in associated with one or more capacitors to provide either a high pass or low pass touch-control audio filter. In a totally polyphonic instrument a tone generator and touch-control filter are respectively associated with and responsive to each key depression, the output signal from each activated filter being coupled preferably to audio mixer circuitry.

A multiple touch switch apparatus has at least one multiple segment conductor ply on the top surface of a support ply. The segments are electrically insulated from each other by their lateral displacement but are immediately adjacent so that a selected one or more of the segments can be contacted in response to a single transverse touch force. A second support ply has a unitary conduction ply on its bottom surface spaced apart from, but facing, the multiple segment conductor ply. At least the second support ply and the unitary conduction ply are resilient deformable into contact with one or more segments of the multiple segment conductor ply. Each of the multiple segment conductors or the unitary conduction ply or both may incorporate a conductor layer and a pressure sensitive semiconductor composition layer disposed thereon. The semiconductor layer provides a pressure sensitive variable contact resistance in series with the switch. In another embodiment, each multiple segment conductor ply may be replaced by a single segment conductor.