This VCO with discrete components was found documentation from the 1980s. The central frequency with the indicated components is 8 kHz. A BC548 can be used for Q1.
Found in EEE documentation, this circuit can have the duration and frequency adjusted separately....
August 2016 - Mouser Electronics is providing the ew converters step down LM53625-Q1 and...
The circuit is from a 1966 English magazine, but it can be assembled with more modern transistors such as...