A Wien-bridge oscillator can be made Vllriable by using two frequency-determining parts that are varied simultaneously at high tracking accuracy. High-quality tracking potentiometers or variable capacitors are, however, expensive and difficult to obtain. To avoid having to use such a component, this oscillator was designed to operate with a single potentiometer.
With preset P2 you can adjust the overall amplification so that the output -signal has a reasonably stable amplitude, 3.5 Vpp max., over the entire frequency range. The stated components allow the frequency to be adjusted between 350 Hz and 3.5 kHz.