This 3-valve receiver was found in a publication by Edelman from 1924. The circuit has two supply voltages, B being 60 to 90 V.
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...