This circuit was found in General Electric documentation from 1964. It makes use of a PUT, called the PNPN planar key at the time. The circuit has two supply voltages.
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...