This circuit was obtained in an American documentation from the 80's. The transistors can be equivalent to those indicated and the crystal can reach a few tens of megahertz.
The sophisticated signal tracker/follower with a JFET and integrated circuit 741 was found in a...
The gain of this circuit is given by the value of R1 that depends on the current in the...
This electronic switch published in the July 1970 Radio Electronics magazine allows the...