This operational amplifier circuit with variable gain was obtained in an 80's Electronic Engineering. The circuit applies to other operational amplifiers.
Used by the police this receiver tuned to the low VHF band. The circuit is from a documentation from the...
This circuit, for bands above 15 MHz, was found in an Argentine publication from the 1970s. The L1...
Found in documentation from the 1980s, this circuit can be used with other operational ones. The...