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.
The transistors of this old circuit from the 60s can be the BC548, in a current version. The...
This electronic soldering gun circuit was found in the December 1998 Electronics Now magazine. The article...
This circuit was found in an American documentation from the 90's. What it does is provide at the...