This circuit is from 1964 documentation but can be easily implemented based on current components. Input waveforms and detection are shown next to the diagram.
This useful signal injector using two transistor was found in a Radio Electronics Magazine from...
In this circuit, from a 1977 publication, we have the traditional version of a filter tuned to 1...
The National Semiconductor operational amplifier, now owned by the Texas Instruments group, is no...