This oscillator that generates signals below the audible range (sub audio or infrasound) was found in a 1965 documentation. Transistors are for general use.
This circuit was found in a 1980s Intersil documentation. The integrated circuit used is not...
Although it is a common configuration today, these circuits were taken from an old publication. The...
This circuit, from an old publication, can also use modern transistors. Note that the unit is...