Found in Exar documentation from the 1980s, this circuit has a 60 dB cutoff at 1800 Hz. The circuit can be adapted to operate at other frequencies.
This circuit was obtained from a 1985 Electronic Desing. The circuit uses a Darlington which may be...
This high selectivity circuit for single tone decoding was found in 1970s documentation. The coil...
This circuit for analogue TV was found in an American 1980s documentation. The transistor can be any RF...