This indicator or logic probe was found in the April 1979 Radio Electronics magazine. The integrated circuit is the 555 and the FET can be any general-purpose type.
This original 70s RCA circuit appears elsewhere on this site, including original RCA...
This circuit, which makes an astable multivibrator, was found in the March 1973 issue of Radio...
This circuit uses two unijunction transistors and only one capacitor, generating signals at a...