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I'm new to the electronics world and am trying to find out if there is a general rule of thumb for relating resistor values to steps in a keyboard... i.e. if there is something like 100 ohms between c and c#. help please! All i'm using is a simple 40106 oscillator.
If piano keyboard frequencies are equally spaced on a logarithmic scale, then yes.
But the 100 ohms would increase by some constant factor, not stay at an absolute value of 100. The factor is what stays constant.
A above middle C is 440 Hz and middle C is 261.63 Hz so your resistor values for A would be 440Ω and for C, 261.63 Ω, or some multiple of that, e.g., 4400 Ω and 2616.3Ω. Absolute freq. accuracy isn't necessary unless you are going to accompany other instruments.
You may be able to find 1% resistor values that match these values closely. The question is, how close do you need for an untrained ear? 1%? 0.1%? Better than that? This gets into physiology. An upper limit on accuracy would be for the difference to be indistinguishable by an experienced conductor.
This application is ideal for a spreadsheet. You want to map as many frequencies to as many 1% resistor values as possible, without having to pad resistors.
A better way is to make dividers that follow this 12th root of 2 sequence and use one master clock.