Originally designed for WWV (Standard Time Station) signals, it lets 1 kHz tones pass by rejecting the 440 and 600 Hz tones emitted by the station. The circuit is from a 1964 Electronic Design.
This low pass filter has attenuation of 5.5 dB and the frequencies depend on the values of the...
This circuit is from an old 80's linear circuit manual. The configuration can be implemented with modern...
Found in an American 1980s documentation, this circuit makes use of a sensor of the era uncommon...