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 circuit was found in an 80's Electronic Engineering. The circuit uses operatives of the time...
The selected circuit was obtained in a Texas Instruments opto-electronics manual. The transistors can be...
In short wave receivers or in the recovery of signals from scratched discs this circuit can be...