This circuit from the 90s, found in an Electronic Engineering can be used as a shield since its control is digital with TTL logic of 5 V. The components used are still common today.
Pressing and releasing S, the capacitor C1 charges and discharge slowly through the oscillator...
We found this touch control on a Popular Electronics from 1970. The circuit makes use of an...
Found in a 1990s US publication, this alarm circuit detects when a light beam is interrupted. Optical...