We found this circuit in a publication from the 1980s. Transistors can be replaced by current equivalents. The circuit is for 6 V and the capacitors determine the frequency of the oscillations.
This precision speed control was obtained in an Electronic Design from the 90's. The output final...
Using the name of varactor this circuit was found in the Radio Electronics magazine of July 1982....
This trigger circuit was found in an American documentation from the 1980s. The amplifiers used...