Circuit for preferentially selecting highest and lowest tones

In an electronic keyboard musical instrument, a circuit for preferentially selecting the highest and the lowest tones from among the tones in chords produced by keys on the keyboard which have been struck, said circuit comprising:

• a set of resistors having equal value connected in series, the number of resistors in said set being one more than the number of tones from which the highest and lowest tones are to be selected;
• an end resistor connected between each end of said set of resistors and a reference voltage level;
• a plurality of transistors each having the emitter thereof connected to said set of resistors at a junction between two resistors of said set which corresponds to the transistor and having the collector thereof adapted to receive a corresponding tone signal, the number of transistors corresponding to the number of tones from which the highest and lowest tones are to be selected;
• a plurality of keyswitches, one connected to the base of each transistor and to a bias source, for connecting the base of the transistor to said bias source when the corresponding tone is played;
• two switch means, one connected between each end of said set of resistors and the corresponding end resistor;
• means connected to said switch means for alternately opening and closing said switch means in synchronism;
• and
• shaping and amplifying means coupled to said switch means for alternately receiving signals from opposite ends of said set of resistors through said switch means and for producing an output of uniform amplitude.