The integrated circuit used in this 2002 project is not very common. It is powered directly by the telephone line, requiring no power supply.
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...