This filter was found in Exar documentation from the 1980s. The circuit has an attenuation of 60 dB at the selected frequency. The power supply must be symmetrical.
In fact, this circuit found in a Radio Electronics from November 1964 is a high voltage generator whose...
This configuration was found in old documentation and is valid for most general purpose NPN...
This is the project found in a 1981 publication, but it is still viable. It is a simple AM...