This circuit is from old documentation, using a component that cannot be found easily today. The indicator is a galvanometer, and the input voltage is in the order of 1 V.
This circuit with the PA7601 was found in a 1967 Philco-Ford documentation. The circuit has a pass...
This CMOS version of the force gauge was found in a 1983 publication. In the CMOS version, the...
Using the LM317 (or LM350), this circuit is based on precision regulatory components such as those...