This type of logic is no longer used today. The circuit is from an old American publication and the integrated circuit is uncommon today. Diodes are general-purpose tpes.
This alarm oscillator was found in the December 1974 issue of Radio Electronics magazine. The...
We found this small audio amplifier in the November 1999 issue of Electronics Now magazine. The...
This circuit is a continuation of the previous one, serving as a protector against overloads in...