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.
This circuit matches a source of high or medium impedance audio signals with a low impedance...
Found in a 1993 Electronics Hobbyst Handbook, this circuit uses components that are still common...
This pulse width-tuned circuit was found in the March 1996 issue of Electronics Now magazine. The...