Found in a publication for radio amateurs from the 1980s, this circuit amplifies signals in the 60 kHz band (VLF), Winding data from the ferrite antenna are provided along with the diagram.
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...