How to choose components for VCO?

Question

Electronics

I apologize in advance if the question is stupid - I really like to blunt on simple things or get confused in three pines.

I wanted to assemble a saw generator on a Schmitt trigger and connect to it ... something like an impromptu keyboard for one octave, of course, also homemade. On the one hand, I understand the general principle of work, and on the other hand, there are many stupid questions - porridge in my head. How to choose components? What should be between the base of the transistor and the "keyboard"? Or maybe use a field one instead of a bipolar one? Etc.

In any case, thanks in advance.

Answer 1

what for ?? if the circuit solution is not massively used, then there is usually some kind of underlying reason for this.
try for your 12 keys to use a standard diode matrix 4x3.
regarding the answer: look for a non-arbitrary "spherical in a vacuum" VCO circuit somewhere in the tyrnet.
and look for articles describing the operation of the presented VCO circuit and giving, as part of the description, calculations on the dependence of the frequency on the parameters of the elements and recommendations on the choice of elements.
there are even special books on applied