Need help with Wien-Bridge Oscilator

[purpleclover]

Greetings everyone, i have a assigment and i need to creat a wien bridge oscilator that uses potentiometers so the out frecv can be modified between (10, 14 )Khz...and the out voltage between (6,9) V ... i allready made a sketch but i just cant figure out how to do this...every time i try to make the amplitude bigger the frecvency changes and the other way around. Please, can someone help me ?

 

[godfreyl]

R1 and R2 should be a dual potentiometer to change frequency. R7 should be another potentiometer to change amplitude.

 

[purpleclover]

Thanks Godfreyl for your reply. I didnt add any potentiometers since i didnt really know wher e to put them ...could you please make a quick sketch on how to place them?...dosent have to be exactly just a quick paint sketch so i get a basic ideea cause im preety lost here

 

[godfreyl]

Same circuit you gave in post 1. Just replace R1, R2 and R7 with potentiometers, wired as variable resistors.

R1 and R2 must always be the same, so use a dual potentiometer for that.

 

[Audioguru]

A 741 opamp is 45 years old and works poorly above only 9kHz. Usually a modern audio opamp is used that works well to 100khz.
The diodes in the circuit limit the amplitude by causing clipping distortion. Usually a linear Jfet is used.