[sdiy] vco question

[Jackson LaRose]

hello, my name is jack and i have some questions regarding an RC phase shift oscillator i was hoping
to build.  i wanted to use a JFET as sort of a voltage controlled resistor in the phase shift
network to control the frequency of oscillations.  i was going to use instruments (mainly a bass
guitar)run through an RC high pass filter as the JFET's control voltage. The problem with this is
that i think the amplitude of the signal (how hard or soft i hit the strings of the bass)will also
cause frequency fluctuations in the oscillator that don't relate to the notes being played.  I was
thinking of using another JFET to make a voltage controlled voltage divider before the high pass
filter to keep the amplitude of the control signal constant while maintaining the frequencies to
allow the high pass filter to develop the voltages needed to control the FET in the RC phase shift
network.  Will this work?  If not, is there any way to do this? I was trying to obtain all the parts
i needed from radio shack, so ive cancelled out varactors or even P-channel JFETs, but perhaps
something i'm missing using zeners? i'm fairly new to the field of electronics so i'm sure there is
some trick out there i'm just missing out on
                                                            -Thank You,
                                                              Jack

 

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