The transistor used in this circuit is uncommon today. AC124 or equivalent such as AC188K and 2N2431 can be used. The circuit is from the 80's and makes use of transformers.
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...