This circuit appears on this site from different sources. This is from documentation from the 1980s. The operating system used is uncommon and can be replaced by a more modern equivalent.
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...