I have this circuit, phase-shift oscillator (see attached). I don't know which of the following choices are the frequency-determining components?
1) R2 and R5
2) R1 and R2
3) C1 and R3
4) R1 and C4
I am confused on the two choices 3 and 4 , I am not sure which one to go to? Could you please give me an insights on these two? I am inclined to choose no. 4, hopefully you will help me clear my confusion.. Thank you.
How about eliminating R5 and making R2 the same value as R3 and R4, then adjusting R1 for the proper gain? Since the - input of the opamp is a virtual ground, R2 will then properly load the last section of the phase shift network.
Good idea.
But the oscillator has highpass phase-shift networks that boost distortion. The distortion will be pretty high anyway since there is nothing to keep the opamp from clipping.