The circuit is designed around the Intersil 8038CC. Frequency range is approximately 20 Hz to 20 kHzâ€”a tuning range of 1000:1 with a single control. The output frequency depends on the value of C2 and on the setting of potentiometer Rl. Other values of C2 change the frequency range. Increase the value of C2 to lower the frequency.
The lowest possible frequency is around .001 Hz and the highest is around 300 kHz.