Keyboard circuit (was Stretch tuning a resistor string)

[Tim Daugard]

Some one said use a voltage regulator for the keyboard resistor string.
After thinking about it some more I had a few thoughts. SO tell me where I'm
wrong.

There are some benefits to useing a regulated current source instead of a
regulated voltage source:

The resistor string can be easily set for 1 volt per octave. Put the meter
across the string at the octave points (one, two, three - doesn't matter)
adjust the current source for the needed voltage drop across the resistor
string.

An adjustable resistor at the bottom of the string would allow adjusting the
offset without having any effect on the tuning of the string itself. This
means that just by switching in the proper resistors I can instantly change
the octave (or smaller interval) of the keyboard.

Add a transistor to the bottom of the string and I can instanlty add
vibrato. All notes would be raised and lowered by the same amount, as the
current through the transistor would just change the collector voltage and
offset the string reference by a little.

Is there good reasons not to do it this way?

Tim Daugard