This 100 Hz filter was found in the August 1993 issue of Electronics Now. The components can be modified to operate at other frequencies.
This circuit was found in a 1987 edition of the United States' Hands-On Electronics magazine. The...
This indicator was found in a 1974 publication, but it can be fitted with the BC548 transistor or...
This traditional configuration, found in other articles on the site, was published in a Poptronics of...