This circuit was found in an American documentation from the 70s. The operational amplifier is from that time. Modern equivalents can be used.
This is one of the channels of an amplifier suggested by Westinghouse in 1970s documentation. The circuit...
The basis of this circuit is a double T in the feedback, which has the components calculated to...
This circuit was obtained from American documentation from the 1990s. The transformer can be a car...