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.
This sophisticated model railway controller was found in the November 1969 issue of Radio...
The circuit shown in the figure below is suggested by ON Semiconductor (www.onsemi.com), based on...
In the figure we have the traditional configuration of a pulsator or flasher with low consumption LED...