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.
Similar to other circuits found in this section, this circuit is from a 1996 Electronics World;...
This circuit was suggested by Motorola's Linear Databook of 1990. The integrated circuit, uncommon...
We found this circuit in a 2005 Linear Technology manual. The circuit can operate directly on 3 V to 36 V...