Digital semiconductor circuit for an electronic organ

Digital semiconductor circuit for an electronic organ having a plurality of control inputs, respectively, associated with individual playing keys of a keyboard of the organ and having a lesser number of audio signal outputs compared to the number of control inputs, as well as an audio frequency generator for applying electrical oscillations corresponding to the individual tones of the highest octave provided within playing range of the organ to a respective audio signal input of the semiconductor circuit,

• wherein the individual control inputs are formed, respectively, by an information input of a respective cell of a clock-controlled shift register operated as a parallel-to-series converter, the individual playing keys and the respective control inputs associated therewith having respective connections of such construction that, in depressed condition of a respective playing key, the control input receives a level logical "1" and otherwise a level logical "0",
• wherein both data output of the shift register as well as clock pulses serving for control thereof serve for controlling a switching system forming a connection between the audio signal inputs and the audio signal outputs, a part of the circuit of said switching system comprising a channel selector controlled by the data output serving, in turn, for selecting the audio signal output on the basis of the respectively depressed playing key with the electrical oscillation appertaining to said playing key, the clock pulses effecting information transfer in the shift register being provided additionally also as counting pulses for a digital tone address counter serving for identifying the respectively actuated playing key and the control input associated therewith,
• wherein a plurality of mutually identical circuit parts forming, respectively, an output channel of said switching system, are provided having a signal output forming, respectively, one of said audio signal outputs, said circuit parts, in turn, being fed in similar manner by all electrical oscillations delivered via said audio signal inputs and also being controlled by said channel-selector circuit part of said switching system serving for selecting the respective audio signal output to be addressed, as well as by said digital tone address counter,
• wherein the individual audio signal outputs are applied to respective mutually identical circuit parts each comprising an amplitude controller serving for improving audio quality and for influencing the amplitude of the electric audio signal oscillations delivered by the respective audio signal output, said amplitude-controller circuit parts having outputs for controlling in common an electroacoustic transducer, and
• wherein the circuit parts of which said switching system is comprised have such a construction that, due to actuation of a playing key of the keyboard, each logical "1" transmitted by said data output of the shift register leads directly to addressing of one of said audio signal outputs by the electrical oscillation associated with the respective playing key and received directly or due to frequency division in said switching system due to addressing of the individual audio signal inputs, and that said one audio signal output thus selected is such that the last preceding addressing of said selected one audio signal output is most distant in time when compared with the last addressing of the remaining audio signal outputs.