This circuit, which can serve as a reference for restorations, was found in the October 1989 issue of Radio Electronics magazine. The circuit uses a 5-digit display and a dedicated integrated circuit.
This circuit came out in a publication called Electronics Handbook of 1993. The circuit shows how...
Found in documentation from the 1980s, this circuit makes use of general-purpose diodes and...
This circuit memorizes through an LED indicator if your phone was used during your absence. The...