When the power is cut off, this circuit keeps the flashlight on for a while, allowing it to be located. The circuit is from a Radio Electronics from September 1992.
This proximity sensor circuit is from an 80's documentation. The used integrated circuits are...
Found in Popular Electronics from the 90s, this circuit triggers a bicolor LED to indicate whether a...
This reflex receiver was obtained from a 1963 documentation. The transistors are germanium, and...