Sawtooth wave oscillator is used in cathode ray tube deflection circuitry, in a PWM modulator, or in a analog to digital conversion. You can also use it in your own design, only your imagination can limit its application. Here is one example of the circuit:
The frequency is determined by C1, R1, R2, R3, and R4. This frequency formula can be used to compute the frequency:
Be aware if the real frequency will be slightly different since the formula is only an approximation, and the components values might deviate at some tolerance.