How to improve and add frequency adjustment function to my DIY wave generator?
Look at your circuit carefully, you aren't switching the RCs correctly.
If you are insisting on using a Wien Bridge Oscillator, you should limit it to audio frequencies. Beyond that will be too difficult.
Use a two pole rotary switch to change the capacitance (C1/C2 in my drawing). CircuitLab doesn't have one, use your imagination. Change the cap by a factor of 10 as you rotate the knob.
Use a ganged log potentiometer in series with a smaller value fixed resistor for the resistor (R1/R2 in my drawing). Shoot for about a 11:1 adjustment with the pot.



simulate this circuit &ndash; Schematic created using CircuitLab
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