Found in an Elektor from the 90s, this circuit is suitable for viewing audio signals on an oscilloscope. The operational amplifier admits equivalent.
Found in a 1968 Mullard manual, this circuit can function as an infrared audio link. The...
This circuit was obtained from an American 80's documentation. The balanced mixer can be shown in...
This circuit was found in a 1980s document. The integrated circuit is from the time and the power...