The circuit`s frequency of oscillation is/= 2.8/ [C1 x (R1 + R2)]. Using the values shown, the output frequency can be varied from 60 Hz to 20 kHz by rotating potentiometer R2. A portion of IC1`s output voltage is fed to its noninverting input at pin 3. The voltage serves as a reference for capacitor Cl, which is connected to the noninverting input at pin 2 of the IC.
That capacitor continually charges and discharges around the reference voltage, and the result is a squarewave output. Capacitor C2 decouples the output.