This two-digit digital pressure gauge was found in the 1992 special edition of Radio Electronics Experimenter. A/D converter integrated circuits are uncommon today.
This circuit was obtained from a Hands On-Electronics, an American magazine from January 1987. This...
Using the CA3140 in the figure we have a comparator that goes low in the window voltage space. The...
This circuit is from a Popular Electronics from the 90's. The circuit activates a buzzer with...