This circuit was found in an English publication from the 70s, an article that teaches how to calculate instruments. The circuit is still current and can be built with an analog indicator of 100 uA.
Suggested to power the previous circuit, this power supply was found in the December 1990 issue of...
This is a very useful autotransformer circuit on the bench. We found it in the September 1970...
This circuit was obtained in a 1960 documentation of General Electric. It is applied in the...