This circuit was obtained in the 1990 Motorola Linear Databook. The circuit uses a 139 series comparator, but other series can be used. The power source need not be symmetric.
Found in old documentation, this oscillator with the LM380 produces an audio tone in a speaker....
The integrated circuit used in this configuration is uncommon today. The diodes are for general use...
This circuit was found in a Radio Escuela Gráfica magazine from Argentina published in the 70's....