Published in an old Popular Electronics, this circuit makes use of components that are still current. The circuit must be powered with 9 V and eventually adapted to function as a shield.
Found in Exar documentation from the 1980s, this circuit has a 60 dB cutoff at 1800 Hz. The...
This circuit is from a Radio Electronics from December 1990. The circuit was used in a home...
In the figure we have the way to make the connection of voltage regulators in series to obtain a...