Found in American documentation from the 90's, this circuit applies to other operational amplifiers. The frequency can be changed by changing the components.
This circuit, from an 80's publication, detects the SCA (Announcer Eliminator) signal from FM...
The circuit is from the Linear Application Handbook. The resistors determine the voltage applied to...
USB58xx and USB59xx Devices Integrate a 2:1 Multiplexer to Support Reversible Connection of USB...