This circuit was found in documentation from the 1970s. However, it can be implemented with modern transistors such as 2N2222 for Q1 and BF494 for Q2. The crystal depends on the desired frequency.
April 2017 - Microchip's new PICLF153 microcontrollers that already incorporate analog and...
With the precision given by the crystal this circuit provides signals of several frequencies for the...
The transistors of this circuit found in an English 1980s documentation may be the modern BC548...