Hello,
Can i use another 4070 for the +2 octave up?
Thx!
Short answer: yes.
Long answer:
Anytime you put a square wave into one input of an XOR, and a slightly delayed (by the r-c network) version of the same square wave into the other input, you get a High output when only one input is high, which happens be twice the input frequency.
If the RC delay is 1/4 the period of the input frequency, the output will be a square wave (50% duty cycle). For other input frequencies, the fixed RC delay will cause the output will be more or less than 50%, which in subjective terms results in a thinner or reedier tone.
Getting back to your question, stacking RC-delayed XOR networks (just like I drew in the schematic in reply #56)
will result in doubling the frequency each time, but the tone will become much thinner, over a broader range of input frequencies.
This is why I put the output of the 4th XOR into the clock input of the 4024. The Q
0 output is now one octave lower than the clock frequency, but the flip-flop circuit makes the duty cycle exactly 50%, and the output's timbre is independent of input frequency. I chose this because I was worried the XOR output would be such a narrow pulse that it would be completely inaudible, not because I think it would necessarily sound better. Having an output which changes dynamically per the frequency will probably sound more interesting, but that's up to your ear to decide.
I'm assuming you've also checked out the Slacktave MKII, correct? There are many ways of putting this thing together.
