This circuit was found in the July 1998 issue of Electronis Now magazine. It is a traditional gated version of the 4049 and has its frequency controlled by R2.
This circuit activates an output, which can be a lock, only when a card containing the programmed code...
Found in an October 1992 Radio Electronics magazine article, this circuit generates a low-power tone in...
Found in a manufacturer documentation from the 90s, this circuit makes use of period components. The...