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.
This circuit was obtained from an English magazine from 1977. The magazine no longer exists, but...
We found this very simple cable fitting circuit in an Electronics Now from the 90s. ...
We found this circuit in a 2005 Linear Technology manual. Observe the component values and...