two more piano octaves

Readers who have built the five octave version of the Elektor piano can extend its frequency range by the addition of two more octaves with the simple circuit shown here. In the circuit diagram of the master tone generator ( E lektor 41 page 9-10) it will be seen that, when the fre- quency of the master oscillator ( IC13) is divided by two, the fre- quency of each note is also divided by two. This causes the range of the keyboard to be shifted downwards by one octave. This disadvantage is turned into an advantage in the circuit described here. The physical modifications to the piano are very straightforward. The tone "positions" of the keying circuit boards, relative to the master tone generator, have to be moved "up" one octave. That is, the connections on the tone generator board for octave 1 are removed and rewired to the position of octave 8. This is continued with all the keying circuit boards until octave 5 occupies the position of octave 4 on the master tone generator board...