Found in an old Popular Electronics this circuit can also be adapted to be used as a shield. In this version the control can trigger loads from the light that falls on an LDR.
The integrated circuit used in this project is not common today, but it can be implemented with more...
Found in an American publication from 1969, this circuit can be adapted to be used as a shield....
This current meter with many scales was found in a 80s American documentation. The operational amplifier...