This schematic shows an example of 3 Rolands (D20) Synth switches of C, E and G. This circuit exist 12 times for the 12 different tunes of an octave.
As you see, each Roland key switch has two switches. The Roland Synth uses conductive material as switch to soften transients (like in PC-keyboards!)
Question: I need to connect these switches to a 120-button accordion accompaniment. When I press the accordion's C-major button these three tunes should sound at the same time, forming the c-major chord.
What's the simplest way of doing this?
Can I just use diodes and directly connect to Roland key switches?
Or use two transistors per Roland key switch?
Or have I to use 4066B?

 

You may find that the conductive material in the key switches is not for "Softening Transients" but the variing resistance, and speed of change may help calculate key velocity and aftertouch which these keyboards use.. (one of the reasons.... along with the sequencer) I bought mine back in the 80's.
I now use it purely as a MIDI controller, and do everything else using PC software (like Band in a Box and Cakewalk) and use higher quality sound modules for the sounds themselves. Another possible option for you.

 

Thx for the reply. I don't really have a problem with touch sensivity, rather with how best to connect my 120-button accordion accompaniment to the Synth switches, as shown in the above circuit.