This circuit was found in an American documentation from the 1980s. The circuit combines filters of different types in a single structure, each of which can be programmed for a frequency.
The transistors in this circuit are 2N2222 and general-purpose diodes 1N4148. The circuit is from...
Figure Bellow shows how to interface CMOS circuitos with TTL using the 4049 or 4050 IC. The power...
This circuit eliminates hiss and other noise from audio sources by cutting frequencies above 10...