Found in the 1969 neon lamp documentation, using neon lamps this circuit provides 18 V regulated with 0 to 4 mA current. The lamps are types of the time.
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...