This two-port configuration of the 4001 was found in the April 1988 issue of Radio Electronics magazine. The timings are given by R1 and C1 as a function of the desired behavior of the circuit.
Found in a 90s Popular Electronics, this touch switch uses a single sensor. PLLs are common today....
We found this circuit in an old documentation from 1979. It is a logic level tester that is...
This ultrasonic insect repellent was found in American documentation from the 1980s. The...