This circuit by Ferranti, in a 1967 publication, is intended for reading perforated tapes. The circuit uses transistors from the era that can be replaced by modern equivalents.
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...