The circuit is from the 1994 National Semiconductor Linear Applications Handbook but can be implemented with more modern operational amplifiers. The power supply must be symmetrical.
This simple circuit can use any general-purpose transistor. The power supply must be isolated. The circuit...
This is a configuration much explored by assemblers, being found on this site in dozens of similar...
The frequency of this oscillator depends on T, which for the audio band can be a common output...