This circuit is from an article that appeared in the June 1974 issue of Radio Electronics magazine. The circuit used integrated circuits and transistors of the time and included 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...