Found in American documentation from 1968, this circuit has an acute cut-off of the frequency to which it is tuned and which depends on RC. Transistors may be modern equivalents of general use.
This PLL with operational amplifiers was found in 1969 documentation. The configuration can be...
This high-gain circuit uses junction FETs (JFETs) and must be powered by somewhat high voltages. The...
The circuit presented is from a 1977 Italian magazine (Elettronica Pratica). We can mount it with...