We found this simple circuit in December 1975 Radio Electronics magazine. The integrated circuit is the 4009 CMOS, and the circuit works in both TTL and CMOS depending on the power supply.
This circuit was obtained from an American 80's documentation. The balanced mixer can be shown in...
This circuit was found in a 90s Electronic Engineering. The quadruple operational amplifier can be...
I found this circuit in an English publication from 1989. This configuration can be mounted with...