This circuit was found in a 1980s documentation. Similar configurations appear in the section, but from different sources. The circuit makes use of components of the time.
Similar circuits can be found on this site. This is from an 80's American documentation. The...
To operate with high input voltages using a 3-terminal voltage regulator such as the LM340-15, we...
This simple multimeter takes advantage of the low cost common galvanometer of 200 uA or 1 mA and...