Found in Popular Electronics from the 90s, this circuit uses a reed switch on the rails as a sensor. Instead of lamps, in a modern version, LEDs can be used.
This circuit has its frequency controlled by a 1MHz crystal. The circuit can be powered by...
This circuit, found in a 2000 documentation, is used in simple artificial intelligence and robotic...
Found in National Semiconductor documentation from the 1990s, this circuit switches video signals to...