Found in a 1980s telecommunications documentation, the circuit presented acts as a product detector. The modulator or mixer in the square may be that of the previous circuit.
With a mains-rated transformer and 1:1 winding this benchtop circuit was found in the January 1995...
This interesting 80's EDN circuit divides the input pulse frequency by a number given by n...
We find this automatic battery charger in an 80s ON Semiconductor circuit and application manual. Bridge...