Using diodes & resistors, instead 4066B

[kchriste]

Why can't you do something like this?

 

[ClydeCrashKop]

That looks OK to me. If A,B and C are logic level inputs, you will need pull down resistors to ground so they are +5 and 0 volts instead of +5 and open. You may also need switch debouncing as well.

 

[jjjjjj]

Sorry, I got it wrong! After re-thinking my circuit I now got it right (I think):
Q: Is this simple circuit OK or do I have to use AND gates?
Normally both, Minor & 7th outputs should be earthed out, so that pressing accordion C-Button sends +5V only to C output. If then I want MINOR, I open SW Minor and a# tune is added (visa-versa with 7th)
So, this circuit is repeated for the whole octave (12 times):
**broken link removed**

The outputs go to 4066B (quadSW) gates; i.e. there only small currents.
This circuitry I only used to switch Live-Styler (YamahaStyles) accompaniment software, because I want to connect 120 accordion pentagonic buttons (from an old Fafisa electronic accordion) to my Synth.
Normally, the software works in the lowest octave of a Synth; requiring to additionally momentarily press the next black key to its left to obtain MINOR or the next white key to its left to obtain 7th accompaniment.
I don't know the resistor values. I want the resistance to be large enough values so as not to load the +5 PS. I guess it's impossible to predict, because all depends on the exact current. Maybe I have to just build a test module two 2-5K Pot's and then reduce its resistance until it works safely...