This is a sine wave generator circuit. It generates an adjustable sine wave betwen 15 Hz to 150 kHz. This circuit uses the principle of Wien-bridge oscillator, with multiple capacitor selection. Here is the circuit:
To control the frequency, this circuit uses a stereo 10K potentiometer. This circuit is using two potentiometers that have a single axis. It was shown by the dashed line connecting both potentiometer.