Found in a 90’s American documentation, this circuit indicates the frequency of input pulses up to 1 kHz. The circuit has a very explored configuration on this site.
This high Q “rejector” or notch filter rejects signals whose frequencies are in the range...
This circuit was found in documentation from the 90's, having an LC compensation network. The...
This two-transistor circuit was found in the January 1994 issue of Electronics Now magazine....