In this receiver the is formed by 80 turns of wire 28 or close in a ferrite rod. The handset is low impedance and powered by a standard battery.
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...