This circuit simulates a resistor controlled by digital signals. We found it in American documentation from the 90s. The basic component is a CMOS 4016 or 4066 digital switch.
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...