This circuit was found in a Radio Electronics magazine from November 1992. The components are from that time and the power supply must be dual.
Found in American documentation from the 1980s, this circuit can be designed with equivalent...
Found in an American paper from the 90's, this circuit can be adjusted to pass frequencies above 30 to 300...
With a mains-rated transformer and 1:1 winding this benchtop circuit was found in the January 1995...