This simple circuit is a continuity test that, in addition to testing resistors, can also test other components. Power is provided by batteries and the LED can be of any color.
This circuit was obtained in an old American documentation, remembering that the 566 is the double...
At each touch of the sensor this counter based on circuit 4017 advances one LED. The circuit can be...
This circuit was obtained in a 1991 Electronics Handbook. The publication no longer exists, but...